mib: add net to TCP_DEC_STATS
[linux-2.6.git] / net / ipv4 / tcp.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the  BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              Implementation of the Transmission Control Protocol(TCP).
7  *
8  * Authors:     Ross Biro
9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
11  *              Corey Minyard <wf-rch!minyard@relay.EU.net>
12  *              Florian La Roche, <flla@stud.uni-sb.de>
13  *              Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
14  *              Linus Torvalds, <torvalds@cs.helsinki.fi>
15  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
16  *              Matthew Dillon, <dillon@apollo.west.oic.com>
17  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
18  *              Jorge Cwik, <jorge@laser.satlink.net>
19  *
20  * Fixes:
21  *              Alan Cox        :       Numerous verify_area() calls
22  *              Alan Cox        :       Set the ACK bit on a reset
23  *              Alan Cox        :       Stopped it crashing if it closed while
24  *                                      sk->inuse=1 and was trying to connect
25  *                                      (tcp_err()).
26  *              Alan Cox        :       All icmp error handling was broken
27  *                                      pointers passed where wrong and the
28  *                                      socket was looked up backwards. Nobody
29  *                                      tested any icmp error code obviously.
30  *              Alan Cox        :       tcp_err() now handled properly. It
31  *                                      wakes people on errors. poll
32  *                                      behaves and the icmp error race
33  *                                      has gone by moving it into sock.c
34  *              Alan Cox        :       tcp_send_reset() fixed to work for
35  *                                      everything not just packets for
36  *                                      unknown sockets.
37  *              Alan Cox        :       tcp option processing.
38  *              Alan Cox        :       Reset tweaked (still not 100%) [Had
39  *                                      syn rule wrong]
40  *              Herp Rosmanith  :       More reset fixes
41  *              Alan Cox        :       No longer acks invalid rst frames.
42  *                                      Acking any kind of RST is right out.
43  *              Alan Cox        :       Sets an ignore me flag on an rst
44  *                                      receive otherwise odd bits of prattle
45  *                                      escape still
46  *              Alan Cox        :       Fixed another acking RST frame bug.
47  *                                      Should stop LAN workplace lockups.
48  *              Alan Cox        :       Some tidyups using the new skb list
49  *                                      facilities
50  *              Alan Cox        :       sk->keepopen now seems to work
51  *              Alan Cox        :       Pulls options out correctly on accepts
52  *              Alan Cox        :       Fixed assorted sk->rqueue->next errors
53  *              Alan Cox        :       PSH doesn't end a TCP read. Switched a
54  *                                      bit to skb ops.
55  *              Alan Cox        :       Tidied tcp_data to avoid a potential
56  *                                      nasty.
57  *              Alan Cox        :       Added some better commenting, as the
58  *                                      tcp is hard to follow
59  *              Alan Cox        :       Removed incorrect check for 20 * psh
60  *      Michael O'Reilly        :       ack < copied bug fix.
61  *      Johannes Stille         :       Misc tcp fixes (not all in yet).
62  *              Alan Cox        :       FIN with no memory -> CRASH
63  *              Alan Cox        :       Added socket option proto entries.
64  *                                      Also added awareness of them to accept.
65  *              Alan Cox        :       Added TCP options (SOL_TCP)
66  *              Alan Cox        :       Switched wakeup calls to callbacks,
67  *                                      so the kernel can layer network
68  *                                      sockets.
69  *              Alan Cox        :       Use ip_tos/ip_ttl settings.
70  *              Alan Cox        :       Handle FIN (more) properly (we hope).
71  *              Alan Cox        :       RST frames sent on unsynchronised
72  *                                      state ack error.
73  *              Alan Cox        :       Put in missing check for SYN bit.
74  *              Alan Cox        :       Added tcp_select_window() aka NET2E
75  *                                      window non shrink trick.
76  *              Alan Cox        :       Added a couple of small NET2E timer
77  *                                      fixes
78  *              Charles Hedrick :       TCP fixes
79  *              Toomas Tamm     :       TCP window fixes
80  *              Alan Cox        :       Small URG fix to rlogin ^C ack fight
81  *              Charles Hedrick :       Rewrote most of it to actually work
82  *              Linus           :       Rewrote tcp_read() and URG handling
83  *                                      completely
84  *              Gerhard Koerting:       Fixed some missing timer handling
85  *              Matthew Dillon  :       Reworked TCP machine states as per RFC
86  *              Gerhard Koerting:       PC/TCP workarounds
87  *              Adam Caldwell   :       Assorted timer/timing errors
88  *              Matthew Dillon  :       Fixed another RST bug
89  *              Alan Cox        :       Move to kernel side addressing changes.
90  *              Alan Cox        :       Beginning work on TCP fastpathing
91  *                                      (not yet usable)
92  *              Arnt Gulbrandsen:       Turbocharged tcp_check() routine.
93  *              Alan Cox        :       TCP fast path debugging
94  *              Alan Cox        :       Window clamping
95  *              Michael Riepe   :       Bug in tcp_check()
96  *              Matt Dillon     :       More TCP improvements and RST bug fixes
97  *              Matt Dillon     :       Yet more small nasties remove from the
98  *                                      TCP code (Be very nice to this man if
99  *                                      tcp finally works 100%) 8)
100  *              Alan Cox        :       BSD accept semantics.
101  *              Alan Cox        :       Reset on closedown bug.
102  *      Peter De Schrijver      :       ENOTCONN check missing in tcp_sendto().
103  *              Michael Pall    :       Handle poll() after URG properly in
104  *                                      all cases.
105  *              Michael Pall    :       Undo the last fix in tcp_read_urg()
106  *                                      (multi URG PUSH broke rlogin).
107  *              Michael Pall    :       Fix the multi URG PUSH problem in
108  *                                      tcp_readable(), poll() after URG
109  *                                      works now.
110  *              Michael Pall    :       recv(...,MSG_OOB) never blocks in the
111  *                                      BSD api.
112  *              Alan Cox        :       Changed the semantics of sk->socket to
113  *                                      fix a race and a signal problem with
114  *                                      accept() and async I/O.
115  *              Alan Cox        :       Relaxed the rules on tcp_sendto().
116  *              Yury Shevchuk   :       Really fixed accept() blocking problem.
117  *              Craig I. Hagan  :       Allow for BSD compatible TIME_WAIT for
118  *                                      clients/servers which listen in on
119  *                                      fixed ports.
120  *              Alan Cox        :       Cleaned the above up and shrank it to
121  *                                      a sensible code size.
122  *              Alan Cox        :       Self connect lockup fix.
123  *              Alan Cox        :       No connect to multicast.
124  *              Ross Biro       :       Close unaccepted children on master
125  *                                      socket close.
126  *              Alan Cox        :       Reset tracing code.
127  *              Alan Cox        :       Spurious resets on shutdown.
128  *              Alan Cox        :       Giant 15 minute/60 second timer error
129  *              Alan Cox        :       Small whoops in polling before an
130  *                                      accept.
131  *              Alan Cox        :       Kept the state trace facility since
132  *                                      it's handy for debugging.
133  *              Alan Cox        :       More reset handler fixes.
134  *              Alan Cox        :       Started rewriting the code based on
135  *                                      the RFC's for other useful protocol
136  *                                      references see: Comer, KA9Q NOS, and
137  *                                      for a reference on the difference
138  *                                      between specifications and how BSD
139  *                                      works see the 4.4lite source.
140  *              A.N.Kuznetsov   :       Don't time wait on completion of tidy
141  *                                      close.
142  *              Linus Torvalds  :       Fin/Shutdown & copied_seq changes.
143  *              Linus Torvalds  :       Fixed BSD port reuse to work first syn
144  *              Alan Cox        :       Reimplemented timers as per the RFC
145  *                                      and using multiple timers for sanity.
146  *              Alan Cox        :       Small bug fixes, and a lot of new
147  *                                      comments.
148  *              Alan Cox        :       Fixed dual reader crash by locking
149  *                                      the buffers (much like datagram.c)
150  *              Alan Cox        :       Fixed stuck sockets in probe. A probe
151  *                                      now gets fed up of retrying without
152  *                                      (even a no space) answer.
153  *              Alan Cox        :       Extracted closing code better
154  *              Alan Cox        :       Fixed the closing state machine to
155  *                                      resemble the RFC.
156  *              Alan Cox        :       More 'per spec' fixes.
157  *              Jorge Cwik      :       Even faster checksumming.
158  *              Alan Cox        :       tcp_data() doesn't ack illegal PSH
159  *                                      only frames. At least one pc tcp stack
160  *                                      generates them.
161  *              Alan Cox        :       Cache last socket.
162  *              Alan Cox        :       Per route irtt.
163  *              Matt Day        :       poll()->select() match BSD precisely on error
164  *              Alan Cox        :       New buffers
165  *              Marc Tamsky     :       Various sk->prot->retransmits and
166  *                                      sk->retransmits misupdating fixed.
167  *                                      Fixed tcp_write_timeout: stuck close,
168  *                                      and TCP syn retries gets used now.
169  *              Mark Yarvis     :       In tcp_read_wakeup(), don't send an
170  *                                      ack if state is TCP_CLOSED.
171  *              Alan Cox        :       Look up device on a retransmit - routes may
172  *                                      change. Doesn't yet cope with MSS shrink right
173  *                                      but it's a start!
174  *              Marc Tamsky     :       Closing in closing fixes.
175  *              Mike Shaver     :       RFC1122 verifications.
176  *              Alan Cox        :       rcv_saddr errors.
177  *              Alan Cox        :       Block double connect().
178  *              Alan Cox        :       Small hooks for enSKIP.
179  *              Alexey Kuznetsov:       Path MTU discovery.
180  *              Alan Cox        :       Support soft errors.
181  *              Alan Cox        :       Fix MTU discovery pathological case
182  *                                      when the remote claims no mtu!
183  *              Marc Tamsky     :       TCP_CLOSE fix.
184  *              Colin (G3TNE)   :       Send a reset on syn ack replies in
185  *                                      window but wrong (fixes NT lpd problems)
186  *              Pedro Roque     :       Better TCP window handling, delayed ack.
187  *              Joerg Reuter    :       No modification of locked buffers in
188  *                                      tcp_do_retransmit()
189  *              Eric Schenk     :       Changed receiver side silly window
190  *                                      avoidance algorithm to BSD style
191  *                                      algorithm. This doubles throughput
192  *                                      against machines running Solaris,
193  *                                      and seems to result in general
194  *                                      improvement.
195  *      Stefan Magdalinski      :       adjusted tcp_readable() to fix FIONREAD
196  *      Willy Konynenberg       :       Transparent proxying support.
197  *      Mike McLagan            :       Routing by source
198  *              Keith Owens     :       Do proper merging with partial SKB's in
199  *                                      tcp_do_sendmsg to avoid burstiness.
200  *              Eric Schenk     :       Fix fast close down bug with
201  *                                      shutdown() followed by close().
202  *              Andi Kleen      :       Make poll agree with SIGIO
203  *      Salvatore Sanfilippo    :       Support SO_LINGER with linger == 1 and
204  *                                      lingertime == 0 (RFC 793 ABORT Call)
205  *      Hirokazu Takahashi      :       Use copy_from_user() instead of
206  *                                      csum_and_copy_from_user() if possible.
207  *
208  *              This program is free software; you can redistribute it and/or
209  *              modify it under the terms of the GNU General Public License
210  *              as published by the Free Software Foundation; either version
211  *              2 of the License, or(at your option) any later version.
212  *
213  * Description of States:
214  *
215  *      TCP_SYN_SENT            sent a connection request, waiting for ack
216  *
217  *      TCP_SYN_RECV            received a connection request, sent ack,
218  *                              waiting for final ack in three-way handshake.
219  *
220  *      TCP_ESTABLISHED         connection established
221  *
222  *      TCP_FIN_WAIT1           our side has shutdown, waiting to complete
223  *                              transmission of remaining buffered data
224  *
225  *      TCP_FIN_WAIT2           all buffered data sent, waiting for remote
226  *                              to shutdown
227  *
228  *      TCP_CLOSING             both sides have shutdown but we still have
229  *                              data we have to finish sending
230  *
231  *      TCP_TIME_WAIT           timeout to catch resent junk before entering
232  *                              closed, can only be entered from FIN_WAIT2
233  *                              or CLOSING.  Required because the other end
234  *                              may not have gotten our last ACK causing it
235  *                              to retransmit the data packet (which we ignore)
236  *
237  *      TCP_CLOSE_WAIT          remote side has shutdown and is waiting for
238  *                              us to finish writing our data and to shutdown
239  *                              (we have to close() to move on to LAST_ACK)
240  *
241  *      TCP_LAST_ACK            out side has shutdown after remote has
242  *                              shutdown.  There may still be data in our
243  *                              buffer that we have to finish sending
244  *
245  *      TCP_CLOSE               socket is finished
246  */
247
248 #include <linux/kernel.h>
249 #include <linux/module.h>
250 #include <linux/types.h>
251 #include <linux/fcntl.h>
252 #include <linux/poll.h>
253 #include <linux/init.h>
254 #include <linux/fs.h>
255 #include <linux/skbuff.h>
256 #include <linux/scatterlist.h>
257 #include <linux/splice.h>
258 #include <linux/net.h>
259 #include <linux/socket.h>
260 #include <linux/random.h>
261 #include <linux/bootmem.h>
262 #include <linux/highmem.h>
263 #include <linux/swap.h>
264 #include <linux/cache.h>
265 #include <linux/err.h>
266 #include <linux/crypto.h>
267
268 #include <net/icmp.h>
269 #include <net/tcp.h>
270 #include <net/xfrm.h>
271 #include <net/ip.h>
272 #include <net/netdma.h>
273 #include <net/sock.h>
274
275 #include <asm/uaccess.h>
276 #include <asm/ioctls.h>
277
278 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
279
280 DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
281
282 atomic_t tcp_orphan_count = ATOMIC_INIT(0);
283
284 EXPORT_SYMBOL_GPL(tcp_orphan_count);
285
286 int sysctl_tcp_mem[3] __read_mostly;
287 int sysctl_tcp_wmem[3] __read_mostly;
288 int sysctl_tcp_rmem[3] __read_mostly;
289
290 EXPORT_SYMBOL(sysctl_tcp_mem);
291 EXPORT_SYMBOL(sysctl_tcp_rmem);
292 EXPORT_SYMBOL(sysctl_tcp_wmem);
293
294 atomic_t tcp_memory_allocated;  /* Current allocated memory. */
295 atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */
296
297 EXPORT_SYMBOL(tcp_memory_allocated);
298 EXPORT_SYMBOL(tcp_sockets_allocated);
299
300 /*
301  * TCP splice context
302  */
303 struct tcp_splice_state {
304         struct pipe_inode_info *pipe;
305         size_t len;
306         unsigned int flags;
307 };
308
309 /*
310  * Pressure flag: try to collapse.
311  * Technical note: it is used by multiple contexts non atomically.
312  * All the __sk_mem_schedule() is of this nature: accounting
313  * is strict, actions are advisory and have some latency.
314  */
315 int tcp_memory_pressure __read_mostly;
316
317 EXPORT_SYMBOL(tcp_memory_pressure);
318
319 void tcp_enter_memory_pressure(void)
320 {
321         if (!tcp_memory_pressure) {
322                 NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES);
323                 tcp_memory_pressure = 1;
324         }
325 }
326
327 EXPORT_SYMBOL(tcp_enter_memory_pressure);
328
329 /*
330  *      Wait for a TCP event.
331  *
332  *      Note that we don't need to lock the socket, as the upper poll layers
333  *      take care of normal races (between the test and the event) and we don't
334  *      go look at any of the socket buffers directly.
335  */
336 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
337 {
338         unsigned int mask;
339         struct sock *sk = sock->sk;
340         struct tcp_sock *tp = tcp_sk(sk);
341
342         poll_wait(file, sk->sk_sleep, wait);
343         if (sk->sk_state == TCP_LISTEN)
344                 return inet_csk_listen_poll(sk);
345
346         /* Socket is not locked. We are protected from async events
347          * by poll logic and correct handling of state changes
348          * made by other threads is impossible in any case.
349          */
350
351         mask = 0;
352         if (sk->sk_err)
353                 mask = POLLERR;
354
355         /*
356          * POLLHUP is certainly not done right. But poll() doesn't
357          * have a notion of HUP in just one direction, and for a
358          * socket the read side is more interesting.
359          *
360          * Some poll() documentation says that POLLHUP is incompatible
361          * with the POLLOUT/POLLWR flags, so somebody should check this
362          * all. But careful, it tends to be safer to return too many
363          * bits than too few, and you can easily break real applications
364          * if you don't tell them that something has hung up!
365          *
366          * Check-me.
367          *
368          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
369          * our fs/select.c). It means that after we received EOF,
370          * poll always returns immediately, making impossible poll() on write()
371          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
372          * if and only if shutdown has been made in both directions.
373          * Actually, it is interesting to look how Solaris and DUX
374          * solve this dilemma. I would prefer, if POLLHUP were maskable,
375          * then we could set it on SND_SHUTDOWN. BTW examples given
376          * in Stevens' books assume exactly this behaviour, it explains
377          * why POLLHUP is incompatible with POLLOUT.    --ANK
378          *
379          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
380          * blocking on fresh not-connected or disconnected socket. --ANK
381          */
382         if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
383                 mask |= POLLHUP;
384         if (sk->sk_shutdown & RCV_SHUTDOWN)
385                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
386
387         /* Connected? */
388         if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
389                 /* Potential race condition. If read of tp below will
390                  * escape above sk->sk_state, we can be illegally awaken
391                  * in SYN_* states. */
392                 if ((tp->rcv_nxt != tp->copied_seq) &&
393                     (tp->urg_seq != tp->copied_seq ||
394                      tp->rcv_nxt != tp->copied_seq + 1 ||
395                      sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data))
396                         mask |= POLLIN | POLLRDNORM;
397
398                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
399                         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
400                                 mask |= POLLOUT | POLLWRNORM;
401                         } else {  /* send SIGIO later */
402                                 set_bit(SOCK_ASYNC_NOSPACE,
403                                         &sk->sk_socket->flags);
404                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
405
406                                 /* Race breaker. If space is freed after
407                                  * wspace test but before the flags are set,
408                                  * IO signal will be lost.
409                                  */
410                                 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
411                                         mask |= POLLOUT | POLLWRNORM;
412                         }
413                 }
414
415                 if (tp->urg_data & TCP_URG_VALID)
416                         mask |= POLLPRI;
417         }
418         return mask;
419 }
420
421 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
422 {
423         struct tcp_sock *tp = tcp_sk(sk);
424         int answ;
425
426         switch (cmd) {
427         case SIOCINQ:
428                 if (sk->sk_state == TCP_LISTEN)
429                         return -EINVAL;
430
431                 lock_sock(sk);
432                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
433                         answ = 0;
434                 else if (sock_flag(sk, SOCK_URGINLINE) ||
435                          !tp->urg_data ||
436                          before(tp->urg_seq, tp->copied_seq) ||
437                          !before(tp->urg_seq, tp->rcv_nxt)) {
438                         answ = tp->rcv_nxt - tp->copied_seq;
439
440                         /* Subtract 1, if FIN is in queue. */
441                         if (answ && !skb_queue_empty(&sk->sk_receive_queue))
442                                 answ -=
443                        tcp_hdr((struct sk_buff *)sk->sk_receive_queue.prev)->fin;
444                 } else
445                         answ = tp->urg_seq - tp->copied_seq;
446                 release_sock(sk);
447                 break;
448         case SIOCATMARK:
449                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
450                 break;
451         case SIOCOUTQ:
452                 if (sk->sk_state == TCP_LISTEN)
453                         return -EINVAL;
454
455                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
456                         answ = 0;
457                 else
458                         answ = tp->write_seq - tp->snd_una;
459                 break;
460         default:
461                 return -ENOIOCTLCMD;
462         }
463
464         return put_user(answ, (int __user *)arg);
465 }
466
467 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
468 {
469         TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
470         tp->pushed_seq = tp->write_seq;
471 }
472
473 static inline int forced_push(struct tcp_sock *tp)
474 {
475         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
476 }
477
478 static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
479 {
480         struct tcp_sock *tp = tcp_sk(sk);
481         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
482
483         skb->csum    = 0;
484         tcb->seq     = tcb->end_seq = tp->write_seq;
485         tcb->flags   = TCPCB_FLAG_ACK;
486         tcb->sacked  = 0;
487         skb_header_release(skb);
488         tcp_add_write_queue_tail(sk, skb);
489         sk->sk_wmem_queued += skb->truesize;
490         sk_mem_charge(sk, skb->truesize);
491         if (tp->nonagle & TCP_NAGLE_PUSH)
492                 tp->nonagle &= ~TCP_NAGLE_PUSH;
493 }
494
495 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
496                                 struct sk_buff *skb)
497 {
498         if (flags & MSG_OOB) {
499                 tp->urg_mode = 1;
500                 tp->snd_up = tp->write_seq;
501         }
502 }
503
504 static inline void tcp_push(struct sock *sk, int flags, int mss_now,
505                             int nonagle)
506 {
507         struct tcp_sock *tp = tcp_sk(sk);
508
509         if (tcp_send_head(sk)) {
510                 struct sk_buff *skb = tcp_write_queue_tail(sk);
511                 if (!(flags & MSG_MORE) || forced_push(tp))
512                         tcp_mark_push(tp, skb);
513                 tcp_mark_urg(tp, flags, skb);
514                 __tcp_push_pending_frames(sk, mss_now,
515                                           (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
516         }
517 }
518
519 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
520                                 unsigned int offset, size_t len)
521 {
522         struct tcp_splice_state *tss = rd_desc->arg.data;
523
524         return skb_splice_bits(skb, offset, tss->pipe, tss->len, tss->flags);
525 }
526
527 static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
528 {
529         /* Store TCP splice context information in read_descriptor_t. */
530         read_descriptor_t rd_desc = {
531                 .arg.data = tss,
532         };
533
534         return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
535 }
536
537 /**
538  *  tcp_splice_read - splice data from TCP socket to a pipe
539  * @sock:       socket to splice from
540  * @ppos:       position (not valid)
541  * @pipe:       pipe to splice to
542  * @len:        number of bytes to splice
543  * @flags:      splice modifier flags
544  *
545  * Description:
546  *    Will read pages from given socket and fill them into a pipe.
547  *
548  **/
549 ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
550                         struct pipe_inode_info *pipe, size_t len,
551                         unsigned int flags)
552 {
553         struct sock *sk = sock->sk;
554         struct tcp_splice_state tss = {
555                 .pipe = pipe,
556                 .len = len,
557                 .flags = flags,
558         };
559         long timeo;
560         ssize_t spliced;
561         int ret;
562
563         /*
564          * We can't seek on a socket input
565          */
566         if (unlikely(*ppos))
567                 return -ESPIPE;
568
569         ret = spliced = 0;
570
571         lock_sock(sk);
572
573         timeo = sock_rcvtimeo(sk, flags & SPLICE_F_NONBLOCK);
574         while (tss.len) {
575                 ret = __tcp_splice_read(sk, &tss);
576                 if (ret < 0)
577                         break;
578                 else if (!ret) {
579                         if (spliced)
580                                 break;
581                         if (flags & SPLICE_F_NONBLOCK) {
582                                 ret = -EAGAIN;
583                                 break;
584                         }
585                         if (sock_flag(sk, SOCK_DONE))
586                                 break;
587                         if (sk->sk_err) {
588                                 ret = sock_error(sk);
589                                 break;
590                         }
591                         if (sk->sk_shutdown & RCV_SHUTDOWN)
592                                 break;
593                         if (sk->sk_state == TCP_CLOSE) {
594                                 /*
595                                  * This occurs when user tries to read
596                                  * from never connected socket.
597                                  */
598                                 if (!sock_flag(sk, SOCK_DONE))
599                                         ret = -ENOTCONN;
600                                 break;
601                         }
602                         if (!timeo) {
603                                 ret = -EAGAIN;
604                                 break;
605                         }
606                         sk_wait_data(sk, &timeo);
607                         if (signal_pending(current)) {
608                                 ret = sock_intr_errno(timeo);
609                                 break;
610                         }
611                         continue;
612                 }
613                 tss.len -= ret;
614                 spliced += ret;
615
616                 release_sock(sk);
617                 lock_sock(sk);
618
619                 if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
620                     (sk->sk_shutdown & RCV_SHUTDOWN) || !timeo ||
621                     signal_pending(current))
622                         break;
623         }
624
625         release_sock(sk);
626
627         if (spliced)
628                 return spliced;
629
630         return ret;
631 }
632
633 struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
634 {
635         struct sk_buff *skb;
636
637         /* The TCP header must be at least 32-bit aligned.  */
638         size = ALIGN(size, 4);
639
640         skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
641         if (skb) {
642                 if (sk_wmem_schedule(sk, skb->truesize)) {
643                         /*
644                          * Make sure that we have exactly size bytes
645                          * available to the caller, no more, no less.
646                          */
647                         skb_reserve(skb, skb_tailroom(skb) - size);
648                         return skb;
649                 }
650                 __kfree_skb(skb);
651         } else {
652                 sk->sk_prot->enter_memory_pressure();
653                 sk_stream_moderate_sndbuf(sk);
654         }
655         return NULL;
656 }
657
658 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
659                          size_t psize, int flags)
660 {
661         struct tcp_sock *tp = tcp_sk(sk);
662         int mss_now, size_goal;
663         int err;
664         ssize_t copied;
665         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
666
667         /* Wait for a connection to finish. */
668         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
669                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
670                         goto out_err;
671
672         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
673
674         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
675         size_goal = tp->xmit_size_goal;
676         copied = 0;
677
678         err = -EPIPE;
679         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
680                 goto do_error;
681
682         while (psize > 0) {
683                 struct sk_buff *skb = tcp_write_queue_tail(sk);
684                 struct page *page = pages[poffset / PAGE_SIZE];
685                 int copy, i, can_coalesce;
686                 int offset = poffset % PAGE_SIZE;
687                 int size = min_t(size_t, psize, PAGE_SIZE - offset);
688
689                 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
690 new_segment:
691                         if (!sk_stream_memory_free(sk))
692                                 goto wait_for_sndbuf;
693
694                         skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
695                         if (!skb)
696                                 goto wait_for_memory;
697
698                         skb_entail(sk, skb);
699                         copy = size_goal;
700                 }
701
702                 if (copy > size)
703                         copy = size;
704
705                 i = skb_shinfo(skb)->nr_frags;
706                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
707                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
708                         tcp_mark_push(tp, skb);
709                         goto new_segment;
710                 }
711                 if (!sk_wmem_schedule(sk, copy))
712                         goto wait_for_memory;
713
714                 if (can_coalesce) {
715                         skb_shinfo(skb)->frags[i - 1].size += copy;
716                 } else {
717                         get_page(page);
718                         skb_fill_page_desc(skb, i, page, offset, copy);
719                 }
720
721                 skb->len += copy;
722                 skb->data_len += copy;
723                 skb->truesize += copy;
724                 sk->sk_wmem_queued += copy;
725                 sk_mem_charge(sk, copy);
726                 skb->ip_summed = CHECKSUM_PARTIAL;
727                 tp->write_seq += copy;
728                 TCP_SKB_CB(skb)->end_seq += copy;
729                 skb_shinfo(skb)->gso_segs = 0;
730
731                 if (!copied)
732                         TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
733
734                 copied += copy;
735                 poffset += copy;
736                 if (!(psize -= copy))
737                         goto out;
738
739                 if (skb->len < size_goal || (flags & MSG_OOB))
740                         continue;
741
742                 if (forced_push(tp)) {
743                         tcp_mark_push(tp, skb);
744                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
745                 } else if (skb == tcp_send_head(sk))
746                         tcp_push_one(sk, mss_now);
747                 continue;
748
749 wait_for_sndbuf:
750                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
751 wait_for_memory:
752                 if (copied)
753                         tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
754
755                 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
756                         goto do_error;
757
758                 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
759                 size_goal = tp->xmit_size_goal;
760         }
761
762 out:
763         if (copied)
764                 tcp_push(sk, flags, mss_now, tp->nonagle);
765         return copied;
766
767 do_error:
768         if (copied)
769                 goto out;
770 out_err:
771         return sk_stream_error(sk, flags, err);
772 }
773
774 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
775                      size_t size, int flags)
776 {
777         ssize_t res;
778         struct sock *sk = sock->sk;
779
780         if (!(sk->sk_route_caps & NETIF_F_SG) ||
781             !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
782                 return sock_no_sendpage(sock, page, offset, size, flags);
783
784         lock_sock(sk);
785         TCP_CHECK_TIMER(sk);
786         res = do_tcp_sendpages(sk, &page, offset, size, flags);
787         TCP_CHECK_TIMER(sk);
788         release_sock(sk);
789         return res;
790 }
791
792 #define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
793 #define TCP_OFF(sk)     (sk->sk_sndmsg_off)
794
795 static inline int select_size(struct sock *sk)
796 {
797         struct tcp_sock *tp = tcp_sk(sk);
798         int tmp = tp->mss_cache;
799
800         if (sk->sk_route_caps & NETIF_F_SG) {
801                 if (sk_can_gso(sk))
802                         tmp = 0;
803                 else {
804                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
805
806                         if (tmp >= pgbreak &&
807                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
808                                 tmp = pgbreak;
809                 }
810         }
811
812         return tmp;
813 }
814
815 int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
816                 size_t size)
817 {
818         struct sock *sk = sock->sk;
819         struct iovec *iov;
820         struct tcp_sock *tp = tcp_sk(sk);
821         struct sk_buff *skb;
822         int iovlen, flags;
823         int mss_now, size_goal;
824         int err, copied;
825         long timeo;
826
827         lock_sock(sk);
828         TCP_CHECK_TIMER(sk);
829
830         flags = msg->msg_flags;
831         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
832
833         /* Wait for a connection to finish. */
834         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
835                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
836                         goto out_err;
837
838         /* This should be in poll */
839         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
840
841         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
842         size_goal = tp->xmit_size_goal;
843
844         /* Ok commence sending. */
845         iovlen = msg->msg_iovlen;
846         iov = msg->msg_iov;
847         copied = 0;
848
849         err = -EPIPE;
850         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
851                 goto do_error;
852
853         while (--iovlen >= 0) {
854                 int seglen = iov->iov_len;
855                 unsigned char __user *from = iov->iov_base;
856
857                 iov++;
858
859                 while (seglen > 0) {
860                         int copy;
861
862                         skb = tcp_write_queue_tail(sk);
863
864                         if (!tcp_send_head(sk) ||
865                             (copy = size_goal - skb->len) <= 0) {
866
867 new_segment:
868                                 /* Allocate new segment. If the interface is SG,
869                                  * allocate skb fitting to single page.
870                                  */
871                                 if (!sk_stream_memory_free(sk))
872                                         goto wait_for_sndbuf;
873
874                                 skb = sk_stream_alloc_skb(sk, select_size(sk),
875                                                 sk->sk_allocation);
876                                 if (!skb)
877                                         goto wait_for_memory;
878
879                                 /*
880                                  * Check whether we can use HW checksum.
881                                  */
882                                 if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
883                                         skb->ip_summed = CHECKSUM_PARTIAL;
884
885                                 skb_entail(sk, skb);
886                                 copy = size_goal;
887                         }
888
889                         /* Try to append data to the end of skb. */
890                         if (copy > seglen)
891                                 copy = seglen;
892
893                         /* Where to copy to? */
894                         if (skb_tailroom(skb) > 0) {
895                                 /* We have some space in skb head. Superb! */
896                                 if (copy > skb_tailroom(skb))
897                                         copy = skb_tailroom(skb);
898                                 if ((err = skb_add_data(skb, from, copy)) != 0)
899                                         goto do_fault;
900                         } else {
901                                 int merge = 0;
902                                 int i = skb_shinfo(skb)->nr_frags;
903                                 struct page *page = TCP_PAGE(sk);
904                                 int off = TCP_OFF(sk);
905
906                                 if (skb_can_coalesce(skb, i, page, off) &&
907                                     off != PAGE_SIZE) {
908                                         /* We can extend the last page
909                                          * fragment. */
910                                         merge = 1;
911                                 } else if (i == MAX_SKB_FRAGS ||
912                                            (!i &&
913                                            !(sk->sk_route_caps & NETIF_F_SG))) {
914                                         /* Need to add new fragment and cannot
915                                          * do this because interface is non-SG,
916                                          * or because all the page slots are
917                                          * busy. */
918                                         tcp_mark_push(tp, skb);
919                                         goto new_segment;
920                                 } else if (page) {
921                                         if (off == PAGE_SIZE) {
922                                                 put_page(page);
923                                                 TCP_PAGE(sk) = page = NULL;
924                                                 off = 0;
925                                         }
926                                 } else
927                                         off = 0;
928
929                                 if (copy > PAGE_SIZE - off)
930                                         copy = PAGE_SIZE - off;
931
932                                 if (!sk_wmem_schedule(sk, copy))
933                                         goto wait_for_memory;
934
935                                 if (!page) {
936                                         /* Allocate new cache page. */
937                                         if (!(page = sk_stream_alloc_page(sk)))
938                                                 goto wait_for_memory;
939                                 }
940
941                                 /* Time to copy data. We are close to
942                                  * the end! */
943                                 err = skb_copy_to_page(sk, from, skb, page,
944                                                        off, copy);
945                                 if (err) {
946                                         /* If this page was new, give it to the
947                                          * socket so it does not get leaked.
948                                          */
949                                         if (!TCP_PAGE(sk)) {
950                                                 TCP_PAGE(sk) = page;
951                                                 TCP_OFF(sk) = 0;
952                                         }
953                                         goto do_error;
954                                 }
955
956                                 /* Update the skb. */
957                                 if (merge) {
958                                         skb_shinfo(skb)->frags[i - 1].size +=
959                                                                         copy;
960                                 } else {
961                                         skb_fill_page_desc(skb, i, page, off, copy);
962                                         if (TCP_PAGE(sk)) {
963                                                 get_page(page);
964                                         } else if (off + copy < PAGE_SIZE) {
965                                                 get_page(page);
966                                                 TCP_PAGE(sk) = page;
967                                         }
968                                 }
969
970                                 TCP_OFF(sk) = off + copy;
971                         }
972
973                         if (!copied)
974                                 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
975
976                         tp->write_seq += copy;
977                         TCP_SKB_CB(skb)->end_seq += copy;
978                         skb_shinfo(skb)->gso_segs = 0;
979
980                         from += copy;
981                         copied += copy;
982                         if ((seglen -= copy) == 0 && iovlen == 0)
983                                 goto out;
984
985                         if (skb->len < size_goal || (flags & MSG_OOB))
986                                 continue;
987
988                         if (forced_push(tp)) {
989                                 tcp_mark_push(tp, skb);
990                                 __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
991                         } else if (skb == tcp_send_head(sk))
992                                 tcp_push_one(sk, mss_now);
993                         continue;
994
995 wait_for_sndbuf:
996                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
997 wait_for_memory:
998                         if (copied)
999                                 tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
1000
1001                         if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
1002                                 goto do_error;
1003
1004                         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
1005                         size_goal = tp->xmit_size_goal;
1006                 }
1007         }
1008
1009 out:
1010         if (copied)
1011                 tcp_push(sk, flags, mss_now, tp->nonagle);
1012         TCP_CHECK_TIMER(sk);
1013         release_sock(sk);
1014         return copied;
1015
1016 do_fault:
1017         if (!skb->len) {
1018                 tcp_unlink_write_queue(skb, sk);
1019                 /* It is the one place in all of TCP, except connection
1020                  * reset, where we can be unlinking the send_head.
1021                  */
1022                 tcp_check_send_head(sk, skb);
1023                 sk_wmem_free_skb(sk, skb);
1024         }
1025
1026 do_error:
1027         if (copied)
1028                 goto out;
1029 out_err:
1030         err = sk_stream_error(sk, flags, err);
1031         TCP_CHECK_TIMER(sk);
1032         release_sock(sk);
1033         return err;
1034 }
1035
1036 /*
1037  *      Handle reading urgent data. BSD has very simple semantics for
1038  *      this, no blocking and very strange errors 8)
1039  */
1040
1041 static int tcp_recv_urg(struct sock *sk, long timeo,
1042                         struct msghdr *msg, int len, int flags,
1043                         int *addr_len)
1044 {
1045         struct tcp_sock *tp = tcp_sk(sk);
1046
1047         /* No URG data to read. */
1048         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1049             tp->urg_data == TCP_URG_READ)
1050                 return -EINVAL; /* Yes this is right ! */
1051
1052         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1053                 return -ENOTCONN;
1054
1055         if (tp->urg_data & TCP_URG_VALID) {
1056                 int err = 0;
1057                 char c = tp->urg_data;
1058
1059                 if (!(flags & MSG_PEEK))
1060                         tp->urg_data = TCP_URG_READ;
1061
1062                 /* Read urgent data. */
1063                 msg->msg_flags |= MSG_OOB;
1064
1065                 if (len > 0) {
1066                         if (!(flags & MSG_TRUNC))
1067                                 err = memcpy_toiovec(msg->msg_iov, &c, 1);
1068                         len = 1;
1069                 } else
1070                         msg->msg_flags |= MSG_TRUNC;
1071
1072                 return err ? -EFAULT : len;
1073         }
1074
1075         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1076                 return 0;
1077
1078         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1079          * the available implementations agree in this case:
1080          * this call should never block, independent of the
1081          * blocking state of the socket.
1082          * Mike <pall@rz.uni-karlsruhe.de>
1083          */
1084         return -EAGAIN;
1085 }
1086
1087 /* Clean up the receive buffer for full frames taken by the user,
1088  * then send an ACK if necessary.  COPIED is the number of bytes
1089  * tcp_recvmsg has given to the user so far, it speeds up the
1090  * calculation of whether or not we must ACK for the sake of
1091  * a window update.
1092  */
1093 void tcp_cleanup_rbuf(struct sock *sk, int copied)
1094 {
1095         struct tcp_sock *tp = tcp_sk(sk);
1096         int time_to_ack = 0;
1097
1098 #if TCP_DEBUG
1099         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1100
1101         BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
1102 #endif
1103
1104         if (inet_csk_ack_scheduled(sk)) {
1105                 const struct inet_connection_sock *icsk = inet_csk(sk);
1106                    /* Delayed ACKs frequently hit locked sockets during bulk
1107                     * receive. */
1108                 if (icsk->icsk_ack.blocked ||
1109                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
1110                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1111                     /*
1112                      * If this read emptied read buffer, we send ACK, if
1113                      * connection is not bidirectional, user drained
1114                      * receive buffer and there was a small segment
1115                      * in queue.
1116                      */
1117                     (copied > 0 &&
1118                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1119                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1120                        !icsk->icsk_ack.pingpong)) &&
1121                       !atomic_read(&sk->sk_rmem_alloc)))
1122                         time_to_ack = 1;
1123         }
1124
1125         /* We send an ACK if we can now advertise a non-zero window
1126          * which has been raised "significantly".
1127          *
1128          * Even if window raised up to infinity, do not send window open ACK
1129          * in states, where we will not receive more. It is useless.
1130          */
1131         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1132                 __u32 rcv_window_now = tcp_receive_window(tp);
1133
1134                 /* Optimize, __tcp_select_window() is not cheap. */
1135                 if (2*rcv_window_now <= tp->window_clamp) {
1136                         __u32 new_window = __tcp_select_window(sk);
1137
1138                         /* Send ACK now, if this read freed lots of space
1139                          * in our buffer. Certainly, new_window is new window.
1140                          * We can advertise it now, if it is not less than current one.
1141                          * "Lots" means "at least twice" here.
1142                          */
1143                         if (new_window && new_window >= 2 * rcv_window_now)
1144                                 time_to_ack = 1;
1145                 }
1146         }
1147         if (time_to_ack)
1148                 tcp_send_ack(sk);
1149 }
1150
1151 static void tcp_prequeue_process(struct sock *sk)
1152 {
1153         struct sk_buff *skb;
1154         struct tcp_sock *tp = tcp_sk(sk);
1155
1156         NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED);
1157
1158         /* RX process wants to run with disabled BHs, though it is not
1159          * necessary */
1160         local_bh_disable();
1161         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1162                 sk->sk_backlog_rcv(sk, skb);
1163         local_bh_enable();
1164
1165         /* Clear memory counter. */
1166         tp->ucopy.memory = 0;
1167 }
1168
1169 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1170 {
1171         struct sk_buff *skb;
1172         u32 offset;
1173
1174         skb_queue_walk(&sk->sk_receive_queue, skb) {
1175                 offset = seq - TCP_SKB_CB(skb)->seq;
1176                 if (tcp_hdr(skb)->syn)
1177                         offset--;
1178                 if (offset < skb->len || tcp_hdr(skb)->fin) {
1179                         *off = offset;
1180                         return skb;
1181                 }
1182         }
1183         return NULL;
1184 }
1185
1186 /*
1187  * This routine provides an alternative to tcp_recvmsg() for routines
1188  * that would like to handle copying from skbuffs directly in 'sendfile'
1189  * fashion.
1190  * Note:
1191  *      - It is assumed that the socket was locked by the caller.
1192  *      - The routine does not block.
1193  *      - At present, there is no support for reading OOB data
1194  *        or for 'peeking' the socket using this routine
1195  *        (although both would be easy to implement).
1196  */
1197 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1198                   sk_read_actor_t recv_actor)
1199 {
1200         struct sk_buff *skb;
1201         struct tcp_sock *tp = tcp_sk(sk);
1202         u32 seq = tp->copied_seq;
1203         u32 offset;
1204         int copied = 0;
1205
1206         if (sk->sk_state == TCP_LISTEN)
1207                 return -ENOTCONN;
1208         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1209                 if (offset < skb->len) {
1210                         int used;
1211                         size_t len;
1212
1213                         len = skb->len - offset;
1214                         /* Stop reading if we hit a patch of urgent data */
1215                         if (tp->urg_data) {
1216                                 u32 urg_offset = tp->urg_seq - seq;
1217                                 if (urg_offset < len)
1218                                         len = urg_offset;
1219                                 if (!len)
1220                                         break;
1221                         }
1222                         used = recv_actor(desc, skb, offset, len);
1223                         if (used < 0) {
1224                                 if (!copied)
1225                                         copied = used;
1226                                 break;
1227                         } else if (used <= len) {
1228                                 seq += used;
1229                                 copied += used;
1230                                 offset += used;
1231                         }
1232                         /*
1233                          * If recv_actor drops the lock (e.g. TCP splice
1234                          * receive) the skb pointer might be invalid when
1235                          * getting here: tcp_collapse might have deleted it
1236                          * while aggregating skbs from the socket queue.
1237                          */
1238                         skb = tcp_recv_skb(sk, seq-1, &offset);
1239                         if (!skb || (offset+1 != skb->len))
1240                                 break;
1241                 }
1242                 if (tcp_hdr(skb)->fin) {
1243                         sk_eat_skb(sk, skb, 0);
1244                         ++seq;
1245                         break;
1246                 }
1247                 sk_eat_skb(sk, skb, 0);
1248                 if (!desc->count)
1249                         break;
1250         }
1251         tp->copied_seq = seq;
1252
1253         tcp_rcv_space_adjust(sk);
1254
1255         /* Clean up data we have read: This will do ACK frames. */
1256         if (copied > 0)
1257                 tcp_cleanup_rbuf(sk, copied);
1258         return copied;
1259 }
1260
1261 /*
1262  *      This routine copies from a sock struct into the user buffer.
1263  *
1264  *      Technical note: in 2.3 we work on _locked_ socket, so that
1265  *      tricks with *seq access order and skb->users are not required.
1266  *      Probably, code can be easily improved even more.
1267  */
1268
1269 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1270                 size_t len, int nonblock, int flags, int *addr_len)
1271 {
1272         struct tcp_sock *tp = tcp_sk(sk);
1273         int copied = 0;
1274         u32 peek_seq;
1275         u32 *seq;
1276         unsigned long used;
1277         int err;
1278         int target;             /* Read at least this many bytes */
1279         long timeo;
1280         struct task_struct *user_recv = NULL;
1281         int copied_early = 0;
1282         struct sk_buff *skb;
1283
1284         lock_sock(sk);
1285
1286         TCP_CHECK_TIMER(sk);
1287
1288         err = -ENOTCONN;
1289         if (sk->sk_state == TCP_LISTEN)
1290                 goto out;
1291
1292         timeo = sock_rcvtimeo(sk, nonblock);
1293
1294         /* Urgent data needs to be handled specially. */
1295         if (flags & MSG_OOB)
1296                 goto recv_urg;
1297
1298         seq = &tp->copied_seq;
1299         if (flags & MSG_PEEK) {
1300                 peek_seq = tp->copied_seq;
1301                 seq = &peek_seq;
1302         }
1303
1304         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1305
1306 #ifdef CONFIG_NET_DMA
1307         tp->ucopy.dma_chan = NULL;
1308         preempt_disable();
1309         skb = skb_peek_tail(&sk->sk_receive_queue);
1310         {
1311                 int available = 0;
1312
1313                 if (skb)
1314                         available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
1315                 if ((available < target) &&
1316                     (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1317                     !sysctl_tcp_low_latency &&
1318                     __get_cpu_var(softnet_data).net_dma) {
1319                         preempt_enable_no_resched();
1320                         tp->ucopy.pinned_list =
1321                                         dma_pin_iovec_pages(msg->msg_iov, len);
1322                 } else {
1323                         preempt_enable_no_resched();
1324                 }
1325         }
1326 #endif
1327
1328         do {
1329                 u32 offset;
1330
1331                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1332                 if (tp->urg_data && tp->urg_seq == *seq) {
1333                         if (copied)
1334                                 break;
1335                         if (signal_pending(current)) {
1336                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1337                                 break;
1338                         }
1339                 }
1340
1341                 /* Next get a buffer. */
1342
1343                 skb = skb_peek(&sk->sk_receive_queue);
1344                 do {
1345                         if (!skb)
1346                                 break;
1347
1348                         /* Now that we have two receive queues this
1349                          * shouldn't happen.
1350                          */
1351                         if (before(*seq, TCP_SKB_CB(skb)->seq)) {
1352                                 printk(KERN_INFO "recvmsg bug: copied %X "
1353                                        "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
1354                                 break;
1355                         }
1356                         offset = *seq - TCP_SKB_CB(skb)->seq;
1357                         if (tcp_hdr(skb)->syn)
1358                                 offset--;
1359                         if (offset < skb->len)
1360                                 goto found_ok_skb;
1361                         if (tcp_hdr(skb)->fin)
1362                                 goto found_fin_ok;
1363                         BUG_TRAP(flags & MSG_PEEK);
1364                         skb = skb->next;
1365                 } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
1366
1367                 /* Well, if we have backlog, try to process it now yet. */
1368
1369                 if (copied >= target && !sk->sk_backlog.tail)
1370                         break;
1371
1372                 if (copied) {
1373                         if (sk->sk_err ||
1374                             sk->sk_state == TCP_CLOSE ||
1375                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1376                             !timeo ||
1377                             signal_pending(current) ||
1378                             (flags & MSG_PEEK))
1379                                 break;
1380                 } else {
1381                         if (sock_flag(sk, SOCK_DONE))
1382                                 break;
1383
1384                         if (sk->sk_err) {
1385                                 copied = sock_error(sk);
1386                                 break;
1387                         }
1388
1389                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1390                                 break;
1391
1392                         if (sk->sk_state == TCP_CLOSE) {
1393                                 if (!sock_flag(sk, SOCK_DONE)) {
1394                                         /* This occurs when user tries to read
1395                                          * from never connected socket.
1396                                          */
1397                                         copied = -ENOTCONN;
1398                                         break;
1399                                 }
1400                                 break;
1401                         }
1402
1403                         if (!timeo) {
1404                                 copied = -EAGAIN;
1405                                 break;
1406                         }
1407
1408                         if (signal_pending(current)) {
1409                                 copied = sock_intr_errno(timeo);
1410                                 break;
1411                         }
1412                 }
1413
1414                 tcp_cleanup_rbuf(sk, copied);
1415
1416                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1417                         /* Install new reader */
1418                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1419                                 user_recv = current;
1420                                 tp->ucopy.task = user_recv;
1421                                 tp->ucopy.iov = msg->msg_iov;
1422                         }
1423
1424                         tp->ucopy.len = len;
1425
1426                         BUG_TRAP(tp->copied_seq == tp->rcv_nxt ||
1427                                  (flags & (MSG_PEEK | MSG_TRUNC)));
1428
1429                         /* Ugly... If prequeue is not empty, we have to
1430                          * process it before releasing socket, otherwise
1431                          * order will be broken at second iteration.
1432                          * More elegant solution is required!!!
1433                          *
1434                          * Look: we have the following (pseudo)queues:
1435                          *
1436                          * 1. packets in flight
1437                          * 2. backlog
1438                          * 3. prequeue
1439                          * 4. receive_queue
1440                          *
1441                          * Each queue can be processed only if the next ones
1442                          * are empty. At this point we have empty receive_queue.
1443                          * But prequeue _can_ be not empty after 2nd iteration,
1444                          * when we jumped to start of loop because backlog
1445                          * processing added something to receive_queue.
1446                          * We cannot release_sock(), because backlog contains
1447                          * packets arrived _after_ prequeued ones.
1448                          *
1449                          * Shortly, algorithm is clear --- to process all
1450                          * the queues in order. We could make it more directly,
1451                          * requeueing packets from backlog to prequeue, if
1452                          * is not empty. It is more elegant, but eats cycles,
1453                          * unfortunately.
1454                          */
1455                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1456                                 goto do_prequeue;
1457
1458                         /* __ Set realtime policy in scheduler __ */
1459                 }
1460
1461                 if (copied >= target) {
1462                         /* Do not sleep, just process backlog. */
1463                         release_sock(sk);
1464                         lock_sock(sk);
1465                 } else
1466                         sk_wait_data(sk, &timeo);
1467
1468 #ifdef CONFIG_NET_DMA
1469                 tp->ucopy.wakeup = 0;
1470 #endif
1471
1472                 if (user_recv) {
1473                         int chunk;
1474
1475                         /* __ Restore normal policy in scheduler __ */
1476
1477                         if ((chunk = len - tp->ucopy.len) != 0) {
1478                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1479                                 len -= chunk;
1480                                 copied += chunk;
1481                         }
1482
1483                         if (tp->rcv_nxt == tp->copied_seq &&
1484                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1485 do_prequeue:
1486                                 tcp_prequeue_process(sk);
1487
1488                                 if ((chunk = len - tp->ucopy.len) != 0) {
1489                                         NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1490                                         len -= chunk;
1491                                         copied += chunk;
1492                                 }
1493                         }
1494                 }
1495                 if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
1496                         if (net_ratelimit())
1497                                 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1498                                        current->comm, task_pid_nr(current));
1499                         peek_seq = tp->copied_seq;
1500                 }
1501                 continue;
1502
1503         found_ok_skb:
1504                 /* Ok so how much can we use? */
1505                 used = skb->len - offset;
1506                 if (len < used)
1507                         used = len;
1508
1509                 /* Do we have urgent data here? */
1510                 if (tp->urg_data) {
1511                         u32 urg_offset = tp->urg_seq - *seq;
1512                         if (urg_offset < used) {
1513                                 if (!urg_offset) {
1514                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1515                                                 ++*seq;
1516                                                 offset++;
1517                                                 used--;
1518                                                 if (!used)
1519                                                         goto skip_copy;
1520                                         }
1521                                 } else
1522                                         used = urg_offset;
1523                         }
1524                 }
1525
1526                 if (!(flags & MSG_TRUNC)) {
1527 #ifdef CONFIG_NET_DMA
1528                         if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1529                                 tp->ucopy.dma_chan = get_softnet_dma();
1530
1531                         if (tp->ucopy.dma_chan) {
1532                                 tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1533                                         tp->ucopy.dma_chan, skb, offset,
1534                                         msg->msg_iov, used,
1535                                         tp->ucopy.pinned_list);
1536
1537                                 if (tp->ucopy.dma_cookie < 0) {
1538
1539                                         printk(KERN_ALERT "dma_cookie < 0\n");
1540
1541                                         /* Exception. Bailout! */
1542                                         if (!copied)
1543                                                 copied = -EFAULT;
1544                                         break;
1545                                 }
1546                                 if ((offset + used) == skb->len)
1547                                         copied_early = 1;
1548
1549                         } else
1550 #endif
1551                         {
1552                                 err = skb_copy_datagram_iovec(skb, offset,
1553                                                 msg->msg_iov, used);
1554                                 if (err) {
1555                                         /* Exception. Bailout! */
1556                                         if (!copied)
1557                                                 copied = -EFAULT;
1558                                         break;
1559                                 }
1560                         }
1561                 }
1562
1563                 *seq += used;
1564                 copied += used;
1565                 len -= used;
1566
1567                 tcp_rcv_space_adjust(sk);
1568
1569 skip_copy:
1570                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1571                         tp->urg_data = 0;
1572                         tcp_fast_path_check(sk);
1573                 }
1574                 if (used + offset < skb->len)
1575                         continue;
1576
1577                 if (tcp_hdr(skb)->fin)
1578                         goto found_fin_ok;
1579                 if (!(flags & MSG_PEEK)) {
1580                         sk_eat_skb(sk, skb, copied_early);
1581                         copied_early = 0;
1582                 }
1583                 continue;
1584
1585         found_fin_ok:
1586                 /* Process the FIN. */
1587                 ++*seq;
1588                 if (!(flags & MSG_PEEK)) {
1589                         sk_eat_skb(sk, skb, copied_early);
1590                         copied_early = 0;
1591                 }
1592                 break;
1593         } while (len > 0);
1594
1595         if (user_recv) {
1596                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1597                         int chunk;
1598
1599                         tp->ucopy.len = copied > 0 ? len : 0;
1600
1601                         tcp_prequeue_process(sk);
1602
1603                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1604                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1605                                 len -= chunk;
1606                                 copied += chunk;
1607                         }
1608                 }
1609
1610                 tp->ucopy.task = NULL;
1611                 tp->ucopy.len = 0;
1612         }
1613
1614 #ifdef CONFIG_NET_DMA
1615         if (tp->ucopy.dma_chan) {
1616                 dma_cookie_t done, used;
1617
1618                 dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1619
1620                 while (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1621                                                  tp->ucopy.dma_cookie, &done,
1622                                                  &used) == DMA_IN_PROGRESS) {
1623                         /* do partial cleanup of sk_async_wait_queue */
1624                         while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1625                                (dma_async_is_complete(skb->dma_cookie, done,
1626                                                       used) == DMA_SUCCESS)) {
1627                                 __skb_dequeue(&sk->sk_async_wait_queue);
1628                                 kfree_skb(skb);
1629                         }
1630                 }
1631
1632                 /* Safe to free early-copied skbs now */
1633                 __skb_queue_purge(&sk->sk_async_wait_queue);
1634                 dma_chan_put(tp->ucopy.dma_chan);
1635                 tp->ucopy.dma_chan = NULL;
1636         }
1637         if (tp->ucopy.pinned_list) {
1638                 dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1639                 tp->ucopy.pinned_list = NULL;
1640         }
1641 #endif
1642
1643         /* According to UNIX98, msg_name/msg_namelen are ignored
1644          * on connected socket. I was just happy when found this 8) --ANK
1645          */
1646
1647         /* Clean up data we have read: This will do ACK frames. */
1648         tcp_cleanup_rbuf(sk, copied);
1649
1650         TCP_CHECK_TIMER(sk);
1651         release_sock(sk);
1652         return copied;
1653
1654 out:
1655         TCP_CHECK_TIMER(sk);
1656         release_sock(sk);
1657         return err;
1658
1659 recv_urg:
1660         err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len);
1661         goto out;
1662 }
1663
1664 void tcp_set_state(struct sock *sk, int state)
1665 {
1666         int oldstate = sk->sk_state;
1667
1668         switch (state) {
1669         case TCP_ESTABLISHED:
1670                 if (oldstate != TCP_ESTABLISHED)
1671                         TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1672                 break;
1673
1674         case TCP_CLOSE:
1675                 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1676                         TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1677
1678                 sk->sk_prot->unhash(sk);
1679                 if (inet_csk(sk)->icsk_bind_hash &&
1680                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1681                         inet_put_port(sk);
1682                 /* fall through */
1683         default:
1684                 if (oldstate==TCP_ESTABLISHED)
1685                         TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1686         }
1687
1688         /* Change state AFTER socket is unhashed to avoid closed
1689          * socket sitting in hash tables.
1690          */
1691         sk->sk_state = state;
1692
1693 #ifdef STATE_TRACE
1694         SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
1695 #endif
1696 }
1697 EXPORT_SYMBOL_GPL(tcp_set_state);
1698
1699 /*
1700  *      State processing on a close. This implements the state shift for
1701  *      sending our FIN frame. Note that we only send a FIN for some
1702  *      states. A shutdown() may have already sent the FIN, or we may be
1703  *      closed.
1704  */
1705
1706 static const unsigned char new_state[16] = {
1707   /* current state:        new state:      action:      */
1708   /* (Invalid)          */ TCP_CLOSE,
1709   /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1710   /* TCP_SYN_SENT       */ TCP_CLOSE,
1711   /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1712   /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1713   /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1714   /* TCP_TIME_WAIT      */ TCP_CLOSE,
1715   /* TCP_CLOSE          */ TCP_CLOSE,
1716   /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1717   /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1718   /* TCP_LISTEN         */ TCP_CLOSE,
1719   /* TCP_CLOSING        */ TCP_CLOSING,
1720 };
1721
1722 static int tcp_close_state(struct sock *sk)
1723 {
1724         int next = (int)new_state[sk->sk_state];
1725         int ns = next & TCP_STATE_MASK;
1726
1727         tcp_set_state(sk, ns);
1728
1729         return next & TCP_ACTION_FIN;
1730 }
1731
1732 /*
1733  *      Shutdown the sending side of a connection. Much like close except
1734  *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1735  */
1736
1737 void tcp_shutdown(struct sock *sk, int how)
1738 {
1739         /*      We need to grab some memory, and put together a FIN,
1740          *      and then put it into the queue to be sent.
1741          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1742          */
1743         if (!(how & SEND_SHUTDOWN))
1744                 return;
1745
1746         /* If we've already sent a FIN, or it's a closed state, skip this. */
1747         if ((1 << sk->sk_state) &
1748             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1749              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1750                 /* Clear out any half completed packets.  FIN if needed. */
1751                 if (tcp_close_state(sk))
1752                         tcp_send_fin(sk);
1753         }
1754 }
1755
1756 void tcp_close(struct sock *sk, long timeout)
1757 {
1758         struct sk_buff *skb;
1759         int data_was_unread = 0;
1760         int state;
1761
1762         lock_sock(sk);
1763         sk->sk_shutdown = SHUTDOWN_MASK;
1764
1765         if (sk->sk_state == TCP_LISTEN) {
1766                 tcp_set_state(sk, TCP_CLOSE);
1767
1768                 /* Special case. */
1769                 inet_csk_listen_stop(sk);
1770
1771                 goto adjudge_to_death;
1772         }
1773
1774         /*  We need to flush the recv. buffs.  We do this only on the
1775          *  descriptor close, not protocol-sourced closes, because the
1776          *  reader process may not have drained the data yet!
1777          */
1778         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1779                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1780                           tcp_hdr(skb)->fin;
1781                 data_was_unread += len;
1782                 __kfree_skb(skb);
1783         }
1784
1785         sk_mem_reclaim(sk);
1786
1787         /* As outlined in RFC 2525, section 2.17, we send a RST here because
1788          * data was lost. To witness the awful effects of the old behavior of
1789          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
1790          * GET in an FTP client, suspend the process, wait for the client to
1791          * advertise a zero window, then kill -9 the FTP client, wheee...
1792          * Note: timeout is always zero in such a case.
1793          */
1794         if (data_was_unread) {
1795                 /* Unread data was tossed, zap the connection. */
1796                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE);
1797                 tcp_set_state(sk, TCP_CLOSE);
1798                 tcp_send_active_reset(sk, GFP_KERNEL);
1799         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1800                 /* Check zero linger _after_ checking for unread data. */
1801                 sk->sk_prot->disconnect(sk, 0);
1802                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA);
1803         } else if (tcp_close_state(sk)) {
1804                 /* We FIN if the application ate all the data before
1805                  * zapping the connection.
1806                  */
1807
1808                 /* RED-PEN. Formally speaking, we have broken TCP state
1809                  * machine. State transitions:
1810                  *
1811                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1812                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1813                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1814                  *
1815                  * are legal only when FIN has been sent (i.e. in window),
1816                  * rather than queued out of window. Purists blame.
1817                  *
1818                  * F.e. "RFC state" is ESTABLISHED,
1819                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1820                  *
1821                  * The visible declinations are that sometimes
1822                  * we enter time-wait state, when it is not required really
1823                  * (harmless), do not send active resets, when they are
1824                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1825                  * they look as CLOSING or LAST_ACK for Linux)
1826                  * Probably, I missed some more holelets.
1827                  *                                              --ANK
1828                  */
1829                 tcp_send_fin(sk);
1830         }
1831
1832         sk_stream_wait_close(sk, timeout);
1833
1834 adjudge_to_death:
1835         state = sk->sk_state;
1836         sock_hold(sk);
1837         sock_orphan(sk);
1838         atomic_inc(sk->sk_prot->orphan_count);
1839
1840         /* It is the last release_sock in its life. It will remove backlog. */
1841         release_sock(sk);
1842
1843
1844         /* Now socket is owned by kernel and we acquire BH lock
1845            to finish close. No need to check for user refs.
1846          */
1847         local_bh_disable();
1848         bh_lock_sock(sk);
1849         BUG_TRAP(!sock_owned_by_user(sk));
1850
1851         /* Have we already been destroyed by a softirq or backlog? */
1852         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1853                 goto out;
1854
1855         /*      This is a (useful) BSD violating of the RFC. There is a
1856          *      problem with TCP as specified in that the other end could
1857          *      keep a socket open forever with no application left this end.
1858          *      We use a 3 minute timeout (about the same as BSD) then kill
1859          *      our end. If they send after that then tough - BUT: long enough
1860          *      that we won't make the old 4*rto = almost no time - whoops
1861          *      reset mistake.
1862          *
1863          *      Nope, it was not mistake. It is really desired behaviour
1864          *      f.e. on http servers, when such sockets are useless, but
1865          *      consume significant resources. Let's do it with special
1866          *      linger2 option.                                 --ANK
1867          */
1868
1869         if (sk->sk_state == TCP_FIN_WAIT2) {
1870                 struct tcp_sock *tp = tcp_sk(sk);
1871                 if (tp->linger2 < 0) {
1872                         tcp_set_state(sk, TCP_CLOSE);
1873                         tcp_send_active_reset(sk, GFP_ATOMIC);
1874                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER);
1875                 } else {
1876                         const int tmo = tcp_fin_time(sk);
1877
1878                         if (tmo > TCP_TIMEWAIT_LEN) {
1879                                 inet_csk_reset_keepalive_timer(sk,
1880                                                 tmo - TCP_TIMEWAIT_LEN);
1881                         } else {
1882                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
1883                                 goto out;
1884                         }
1885                 }
1886         }
1887         if (sk->sk_state != TCP_CLOSE) {
1888                 sk_mem_reclaim(sk);
1889                 if (tcp_too_many_orphans(sk,
1890                                 atomic_read(sk->sk_prot->orphan_count))) {
1891                         if (net_ratelimit())
1892                                 printk(KERN_INFO "TCP: too many of orphaned "
1893                                        "sockets\n");
1894                         tcp_set_state(sk, TCP_CLOSE);
1895                         tcp_send_active_reset(sk, GFP_ATOMIC);
1896                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY);
1897                 }
1898         }
1899
1900         if (sk->sk_state == TCP_CLOSE)
1901                 inet_csk_destroy_sock(sk);
1902         /* Otherwise, socket is reprieved until protocol close. */
1903
1904 out:
1905         bh_unlock_sock(sk);
1906         local_bh_enable();
1907         sock_put(sk);
1908 }
1909
1910 /* These states need RST on ABORT according to RFC793 */
1911
1912 static inline int tcp_need_reset(int state)
1913 {
1914         return (1 << state) &
1915                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
1916                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
1917 }
1918
1919 int tcp_disconnect(struct sock *sk, int flags)
1920 {
1921         struct inet_sock *inet = inet_sk(sk);
1922         struct inet_connection_sock *icsk = inet_csk(sk);
1923         struct tcp_sock *tp = tcp_sk(sk);
1924         int err = 0;
1925         int old_state = sk->sk_state;
1926
1927         if (old_state != TCP_CLOSE)
1928                 tcp_set_state(sk, TCP_CLOSE);
1929
1930         /* ABORT function of RFC793 */
1931         if (old_state == TCP_LISTEN) {
1932                 inet_csk_listen_stop(sk);
1933         } else if (tcp_need_reset(old_state) ||
1934                    (tp->snd_nxt != tp->write_seq &&
1935                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
1936                 /* The last check adjusts for discrepancy of Linux wrt. RFC
1937                  * states
1938                  */
1939                 tcp_send_active_reset(sk, gfp_any());
1940                 sk->sk_err = ECONNRESET;
1941         } else if (old_state == TCP_SYN_SENT)
1942                 sk->sk_err = ECONNRESET;
1943
1944         tcp_clear_xmit_timers(sk);
1945         __skb_queue_purge(&sk->sk_receive_queue);
1946         tcp_write_queue_purge(sk);
1947         __skb_queue_purge(&tp->out_of_order_queue);
1948 #ifdef CONFIG_NET_DMA
1949         __skb_queue_purge(&sk->sk_async_wait_queue);
1950 #endif
1951
1952         inet->dport = 0;
1953
1954         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1955                 inet_reset_saddr(sk);
1956
1957         sk->sk_shutdown = 0;
1958         sock_reset_flag(sk, SOCK_DONE);
1959         tp->srtt = 0;
1960         if ((tp->write_seq += tp->max_window + 2) == 0)
1961                 tp->write_seq = 1;
1962         icsk->icsk_backoff = 0;
1963         tp->snd_cwnd = 2;
1964         icsk->icsk_probes_out = 0;
1965         tp->packets_out = 0;
1966         tp->snd_ssthresh = 0x7fffffff;
1967         tp->snd_cwnd_cnt = 0;
1968         tp->bytes_acked = 0;
1969         tcp_set_ca_state(sk, TCP_CA_Open);
1970         tcp_clear_retrans(tp);
1971         inet_csk_delack_init(sk);
1972         tcp_init_send_head(sk);
1973         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
1974         __sk_dst_reset(sk);
1975
1976         BUG_TRAP(!inet->num || icsk->icsk_bind_hash);
1977
1978         sk->sk_error_report(sk);
1979         return err;
1980 }
1981
1982 /*
1983  *      Socket option code for TCP.
1984  */
1985 static int do_tcp_setsockopt(struct sock *sk, int level,
1986                 int optname, char __user *optval, int optlen)
1987 {
1988         struct tcp_sock *tp = tcp_sk(sk);
1989         struct inet_connection_sock *icsk = inet_csk(sk);
1990         int val;
1991         int err = 0;
1992
1993         /* This is a string value all the others are int's */
1994         if (optname == TCP_CONGESTION) {
1995                 char name[TCP_CA_NAME_MAX];
1996
1997                 if (optlen < 1)
1998                         return -EINVAL;
1999
2000                 val = strncpy_from_user(name, optval,
2001                                         min(TCP_CA_NAME_MAX-1, optlen));
2002                 if (val < 0)
2003                         return -EFAULT;
2004                 name[val] = 0;
2005
2006                 lock_sock(sk);
2007                 err = tcp_set_congestion_control(sk, name);
2008                 release_sock(sk);
2009                 return err;
2010         }
2011
2012         if (optlen < sizeof(int))
2013                 return -EINVAL;
2014
2015         if (get_user(val, (int __user *)optval))
2016                 return -EFAULT;
2017
2018         lock_sock(sk);
2019
2020         switch (optname) {
2021         case TCP_MAXSEG:
2022                 /* Values greater than interface MTU won't take effect. However
2023                  * at the point when this call is done we typically don't yet
2024                  * know which interface is going to be used */
2025                 if (val < 8 || val > MAX_TCP_WINDOW) {
2026                         err = -EINVAL;
2027                         break;
2028                 }
2029                 tp->rx_opt.user_mss = val;
2030                 break;
2031
2032         case TCP_NODELAY:
2033                 if (val) {
2034                         /* TCP_NODELAY is weaker than TCP_CORK, so that
2035                          * this option on corked socket is remembered, but
2036                          * it is not activated until cork is cleared.
2037                          *
2038                          * However, when TCP_NODELAY is set we make
2039                          * an explicit push, which overrides even TCP_CORK
2040                          * for currently queued segments.
2041                          */
2042                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2043                         tcp_push_pending_frames(sk);
2044                 } else {
2045                         tp->nonagle &= ~TCP_NAGLE_OFF;
2046                 }
2047                 break;
2048
2049         case TCP_CORK:
2050                 /* When set indicates to always queue non-full frames.
2051                  * Later the user clears this option and we transmit
2052                  * any pending partial frames in the queue.  This is
2053                  * meant to be used alongside sendfile() to get properly
2054                  * filled frames when the user (for example) must write
2055                  * out headers with a write() call first and then use
2056                  * sendfile to send out the data parts.
2057                  *
2058                  * TCP_CORK can be set together with TCP_NODELAY and it is
2059                  * stronger than TCP_NODELAY.
2060                  */
2061                 if (val) {
2062                         tp->nonagle |= TCP_NAGLE_CORK;
2063                 } else {
2064                         tp->nonagle &= ~TCP_NAGLE_CORK;
2065                         if (tp->nonagle&TCP_NAGLE_OFF)
2066                                 tp->nonagle |= TCP_NAGLE_PUSH;
2067                         tcp_push_pending_frames(sk);
2068                 }
2069                 break;
2070
2071         case TCP_KEEPIDLE:
2072                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
2073                         err = -EINVAL;
2074                 else {
2075                         tp->keepalive_time = val * HZ;
2076                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
2077                             !((1 << sk->sk_state) &
2078                               (TCPF_CLOSE | TCPF_LISTEN))) {
2079                                 __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
2080                                 if (tp->keepalive_time > elapsed)
2081                                         elapsed = tp->keepalive_time - elapsed;
2082                                 else
2083                                         elapsed = 0;
2084                                 inet_csk_reset_keepalive_timer(sk, elapsed);
2085                         }
2086                 }
2087                 break;
2088         case TCP_KEEPINTVL:
2089                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
2090                         err = -EINVAL;
2091                 else
2092                         tp->keepalive_intvl = val * HZ;
2093                 break;
2094         case TCP_KEEPCNT:
2095                 if (val < 1 || val > MAX_TCP_KEEPCNT)
2096                         err = -EINVAL;
2097                 else
2098                         tp->keepalive_probes = val;
2099                 break;
2100         case TCP_SYNCNT:
2101                 if (val < 1 || val > MAX_TCP_SYNCNT)
2102                         err = -EINVAL;
2103                 else
2104                         icsk->icsk_syn_retries = val;
2105                 break;
2106
2107         case TCP_LINGER2:
2108                 if (val < 0)
2109                         tp->linger2 = -1;
2110                 else if (val > sysctl_tcp_fin_timeout / HZ)
2111                         tp->linger2 = 0;
2112                 else
2113                         tp->linger2 = val * HZ;
2114                 break;
2115
2116         case TCP_DEFER_ACCEPT:
2117                 icsk->icsk_accept_queue.rskq_defer_accept = 0;
2118                 if (val > 0) {
2119                         /* Translate value in seconds to number of
2120                          * retransmits */
2121                         while (icsk->icsk_accept_queue.rskq_defer_accept < 32 &&
2122                                val > ((TCP_TIMEOUT_INIT / HZ) <<
2123                                        icsk->icsk_accept_queue.rskq_defer_accept))
2124                                 icsk->icsk_accept_queue.rskq_defer_accept++;
2125                         icsk->icsk_accept_queue.rskq_defer_accept++;
2126                 }
2127                 break;
2128
2129         case TCP_WINDOW_CLAMP:
2130                 if (!val) {
2131                         if (sk->sk_state != TCP_CLOSE) {
2132                                 err = -EINVAL;
2133                                 break;
2134                         }
2135                         tp->window_clamp = 0;
2136                 } else
2137                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2138                                                 SOCK_MIN_RCVBUF / 2 : val;
2139                 break;
2140
2141         case TCP_QUICKACK:
2142                 if (!val) {
2143                         icsk->icsk_ack.pingpong = 1;
2144                 } else {
2145                         icsk->icsk_ack.pingpong = 0;
2146                         if ((1 << sk->sk_state) &
2147                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2148                             inet_csk_ack_scheduled(sk)) {
2149                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2150                                 tcp_cleanup_rbuf(sk, 1);
2151                                 if (!(val & 1))
2152                                         icsk->icsk_ack.pingpong = 1;
2153                         }
2154                 }
2155                 break;
2156
2157 #ifdef CONFIG_TCP_MD5SIG
2158         case TCP_MD5SIG:
2159                 /* Read the IP->Key mappings from userspace */
2160                 err = tp->af_specific->md5_parse(sk, optval, optlen);
2161                 break;
2162 #endif
2163
2164         default:
2165                 err = -ENOPROTOOPT;
2166                 break;
2167         }
2168
2169         release_sock(sk);
2170         return err;
2171 }
2172
2173 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2174                    int optlen)
2175 {
2176         struct inet_connection_sock *icsk = inet_csk(sk);
2177
2178         if (level != SOL_TCP)
2179                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2180                                                      optval, optlen);
2181         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2182 }
2183
2184 #ifdef CONFIG_COMPAT
2185 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2186                           char __user *optval, int optlen)
2187 {
2188         if (level != SOL_TCP)
2189                 return inet_csk_compat_setsockopt(sk, level, optname,
2190                                                   optval, optlen);
2191         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2192 }
2193
2194 EXPORT_SYMBOL(compat_tcp_setsockopt);
2195 #endif
2196
2197 /* Return information about state of tcp endpoint in API format. */
2198 void tcp_get_info(struct sock *sk, struct tcp_info *info)
2199 {
2200         struct tcp_sock *tp = tcp_sk(sk);
2201         const struct inet_connection_sock *icsk = inet_csk(sk);
2202         u32 now = tcp_time_stamp;
2203
2204         memset(info, 0, sizeof(*info));
2205
2206         info->tcpi_state = sk->sk_state;
2207         info->tcpi_ca_state = icsk->icsk_ca_state;
2208         info->tcpi_retransmits = icsk->icsk_retransmits;
2209         info->tcpi_probes = icsk->icsk_probes_out;
2210         info->tcpi_backoff = icsk->icsk_backoff;
2211
2212         if (tp->rx_opt.tstamp_ok)
2213                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2214         if (tcp_is_sack(tp))
2215                 info->tcpi_options |= TCPI_OPT_SACK;
2216         if (tp->rx_opt.wscale_ok) {
2217                 info->tcpi_options |= TCPI_OPT_WSCALE;
2218                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2219                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2220         }
2221
2222         if (tp->ecn_flags&TCP_ECN_OK)
2223                 info->tcpi_options |= TCPI_OPT_ECN;
2224
2225         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2226         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2227         info->tcpi_snd_mss = tp->mss_cache;
2228         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2229
2230         if (sk->sk_state == TCP_LISTEN) {
2231                 info->tcpi_unacked = sk->sk_ack_backlog;
2232                 info->tcpi_sacked = sk->sk_max_ack_backlog;
2233         } else {
2234                 info->tcpi_unacked = tp->packets_out;
2235                 info->tcpi_sacked = tp->sacked_out;
2236         }
2237         info->tcpi_lost = tp->lost_out;
2238         info->tcpi_retrans = tp->retrans_out;
2239         info->tcpi_fackets = tp->fackets_out;
2240
2241         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2242         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2243         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2244
2245         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2246         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2247         info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2248         info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2249         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2250         info->tcpi_snd_cwnd = tp->snd_cwnd;
2251         info->tcpi_advmss = tp->advmss;
2252         info->tcpi_reordering = tp->reordering;
2253
2254         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2255         info->tcpi_rcv_space = tp->rcvq_space.space;
2256
2257         info->tcpi_total_retrans = tp->total_retrans;
2258 }
2259
2260 EXPORT_SYMBOL_GPL(tcp_get_info);
2261
2262 static int do_tcp_getsockopt(struct sock *sk, int level,
2263                 int optname, char __user *optval, int __user *optlen)
2264 {
2265         struct inet_connection_sock *icsk = inet_csk(sk);
2266         struct tcp_sock *tp = tcp_sk(sk);
2267         int val, len;
2268
2269         if (get_user(len, optlen))
2270                 return -EFAULT;
2271
2272         len = min_t(unsigned int, len, sizeof(int));
2273
2274         if (len < 0)
2275                 return -EINVAL;
2276
2277         switch (optname) {
2278         case TCP_MAXSEG:
2279                 val = tp->mss_cache;
2280                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2281                         val = tp->rx_opt.user_mss;
2282                 break;
2283         case TCP_NODELAY:
2284                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2285                 break;
2286         case TCP_CORK:
2287                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2288                 break;
2289         case TCP_KEEPIDLE:
2290                 val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
2291                 break;
2292         case TCP_KEEPINTVL:
2293                 val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
2294                 break;
2295         case TCP_KEEPCNT:
2296                 val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
2297                 break;
2298         case TCP_SYNCNT:
2299                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2300                 break;
2301         case TCP_LINGER2:
2302                 val = tp->linger2;
2303                 if (val >= 0)
2304                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2305                 break;
2306         case TCP_DEFER_ACCEPT:
2307                 val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 :
2308                         ((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1));
2309                 break;
2310         case TCP_WINDOW_CLAMP:
2311                 val = tp->window_clamp;
2312                 break;
2313         case TCP_INFO: {
2314                 struct tcp_info info;
2315
2316                 if (get_user(len, optlen))
2317                         return -EFAULT;
2318
2319                 tcp_get_info(sk, &info);
2320
2321                 len = min_t(unsigned int, len, sizeof(info));
2322                 if (put_user(len, optlen))
2323                         return -EFAULT;
2324                 if (copy_to_user(optval, &info, len))
2325                         return -EFAULT;
2326                 return 0;
2327         }
2328         case TCP_QUICKACK:
2329                 val = !icsk->icsk_ack.pingpong;
2330                 break;
2331
2332         case TCP_CONGESTION:
2333                 if (get_user(len, optlen))
2334                         return -EFAULT;
2335                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2336                 if (put_user(len, optlen))
2337                         return -EFAULT;
2338                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2339                         return -EFAULT;
2340                 return 0;
2341         default:
2342                 return -ENOPROTOOPT;
2343         }
2344
2345         if (put_user(len, optlen))
2346                 return -EFAULT;
2347         if (copy_to_user(optval, &val, len))
2348                 return -EFAULT;
2349         return 0;
2350 }
2351
2352 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2353                    int __user *optlen)
2354 {
2355         struct inet_connection_sock *icsk = inet_csk(sk);
2356
2357         if (level != SOL_TCP)
2358                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2359                                                      optval, optlen);
2360         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2361 }
2362
2363 #ifdef CONFIG_COMPAT
2364 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2365                           char __user *optval, int __user *optlen)
2366 {
2367         if (level != SOL_TCP)
2368                 return inet_csk_compat_getsockopt(sk, level, optname,
2369                                                   optval, optlen);
2370         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2371 }
2372
2373 EXPORT_SYMBOL(compat_tcp_getsockopt);
2374 #endif
2375
2376 struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2377 {
2378         struct sk_buff *segs = ERR_PTR(-EINVAL);
2379         struct tcphdr *th;
2380         unsigned thlen;
2381         unsigned int seq;
2382         __be32 delta;
2383         unsigned int oldlen;
2384         unsigned int len;
2385
2386         if (!pskb_may_pull(skb, sizeof(*th)))
2387                 goto out;
2388
2389         th = tcp_hdr(skb);
2390         thlen = th->doff * 4;
2391         if (thlen < sizeof(*th))
2392                 goto out;
2393
2394         if (!pskb_may_pull(skb, thlen))
2395                 goto out;
2396
2397         oldlen = (u16)~skb->len;
2398         __skb_pull(skb, thlen);
2399
2400         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2401                 /* Packet is from an untrusted source, reset gso_segs. */
2402                 int type = skb_shinfo(skb)->gso_type;
2403                 int mss;
2404
2405                 if (unlikely(type &
2406                              ~(SKB_GSO_TCPV4 |
2407                                SKB_GSO_DODGY |
2408                                SKB_GSO_TCP_ECN |
2409                                SKB_GSO_TCPV6 |
2410                                0) ||
2411                              !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2412                         goto out;
2413
2414                 mss = skb_shinfo(skb)->gso_size;
2415                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
2416
2417                 segs = NULL;
2418                 goto out;
2419         }
2420
2421         segs = skb_segment(skb, features);
2422         if (IS_ERR(segs))
2423                 goto out;
2424
2425         len = skb_shinfo(skb)->gso_size;
2426         delta = htonl(oldlen + (thlen + len));
2427
2428         skb = segs;
2429         th = tcp_hdr(skb);
2430         seq = ntohl(th->seq);
2431
2432         do {
2433                 th->fin = th->psh = 0;
2434
2435                 th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2436                                        (__force u32)delta));
2437                 if (skb->ip_summed != CHECKSUM_PARTIAL)
2438                         th->check =
2439                              csum_fold(csum_partial(skb_transport_header(skb),
2440                                                     thlen, skb->csum));
2441
2442                 seq += len;
2443                 skb = skb->next;
2444                 th = tcp_hdr(skb);
2445
2446                 th->seq = htonl(seq);
2447                 th->cwr = 0;
2448         } while (skb->next);
2449
2450         delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2451                       skb->data_len);
2452         th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2453                                 (__force u32)delta));
2454         if (skb->ip_summed != CHECKSUM_PARTIAL)
2455                 th->check = csum_fold(csum_partial(skb_transport_header(skb),
2456                                                    thlen, skb->csum));
2457
2458 out:
2459         return segs;
2460 }
2461 EXPORT_SYMBOL(tcp_tso_segment);
2462
2463 #ifdef CONFIG_TCP_MD5SIG
2464 static unsigned long tcp_md5sig_users;
2465 static struct tcp_md5sig_pool **tcp_md5sig_pool;
2466 static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
2467
2468 int tcp_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
2469                       int bplen,
2470                       struct tcphdr *th, unsigned int tcplen,
2471                       struct tcp_md5sig_pool *hp)
2472 {
2473         struct scatterlist sg[4];
2474         __u16 data_len;
2475         int block = 0;
2476         __sum16 cksum;
2477         struct hash_desc *desc = &hp->md5_desc;
2478         int err;
2479         unsigned int nbytes = 0;
2480
2481         sg_init_table(sg, 4);
2482
2483         /* 1. The TCP pseudo-header */
2484         sg_set_buf(&sg[block++], &hp->md5_blk, bplen);
2485         nbytes += bplen;
2486
2487         /* 2. The TCP header, excluding options, and assuming a
2488          * checksum of zero
2489          */
2490         cksum = th->check;
2491         th->check = 0;
2492         sg_set_buf(&sg[block++], th, sizeof(*th));
2493         nbytes += sizeof(*th);
2494
2495         /* 3. The TCP segment data (if any) */
2496         data_len = tcplen - (th->doff << 2);
2497         if (data_len > 0) {
2498                 u8 *data = (u8 *)th + (th->doff << 2);
2499                 sg_set_buf(&sg[block++], data, data_len);
2500                 nbytes += data_len;
2501         }
2502
2503         /* 4. an independently-specified key or password, known to both
2504          * TCPs and presumably connection-specific
2505          */
2506         sg_set_buf(&sg[block++], key->key, key->keylen);
2507         nbytes += key->keylen;
2508
2509         sg_mark_end(&sg[block - 1]);
2510
2511         /* Now store the hash into the packet */
2512         err = crypto_hash_init(desc);
2513         if (err) {
2514                 if (net_ratelimit())
2515                         printk(KERN_WARNING "%s(): hash_init failed\n", __func__);
2516                 return -1;
2517         }
2518         err = crypto_hash_update(desc, sg, nbytes);
2519         if (err) {
2520                 if (net_ratelimit())
2521                         printk(KERN_WARNING "%s(): hash_update failed\n", __func__);
2522                 return -1;
2523         }
2524         err = crypto_hash_final(desc, md5_hash);
2525         if (err) {
2526                 if (net_ratelimit())
2527                         printk(KERN_WARNING "%s(): hash_final failed\n", __func__);
2528                 return -1;
2529         }
2530
2531         /* Reset header */
2532         th->check = cksum;
2533
2534         return 0;
2535 }
2536 EXPORT_SYMBOL(tcp_calc_md5_hash);
2537
2538 static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool **pool)
2539 {
2540         int cpu;
2541         for_each_possible_cpu(cpu) {
2542                 struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu);
2543                 if (p) {
2544                         if (p->md5_desc.tfm)
2545                                 crypto_free_hash(p->md5_desc.tfm);
2546                         kfree(p);
2547                         p = NULL;
2548                 }
2549         }
2550         free_percpu(pool);
2551 }
2552
2553 void tcp_free_md5sig_pool(void)
2554 {
2555         struct tcp_md5sig_pool **pool = NULL;
2556
2557         spin_lock_bh(&tcp_md5sig_pool_lock);
2558         if (--tcp_md5sig_users == 0) {
2559                 pool = tcp_md5sig_pool;
2560                 tcp_md5sig_pool = NULL;
2561         }
2562         spin_unlock_bh(&tcp_md5sig_pool_lock);
2563         if (pool)
2564                 __tcp_free_md5sig_pool(pool);
2565 }
2566
2567 EXPORT_SYMBOL(tcp_free_md5sig_pool);
2568
2569 static struct tcp_md5sig_pool **__tcp_alloc_md5sig_pool(void)
2570 {
2571         int cpu;
2572         struct tcp_md5sig_pool **pool;
2573
2574         pool = alloc_percpu(struct tcp_md5sig_pool *);
2575         if (!pool)
2576                 return NULL;
2577
2578         for_each_possible_cpu(cpu) {
2579                 struct tcp_md5sig_pool *p;
2580                 struct crypto_hash *hash;
2581
2582                 p = kzalloc(sizeof(*p), GFP_KERNEL);
2583                 if (!p)
2584                         goto out_free;
2585                 *per_cpu_ptr(pool, cpu) = p;
2586
2587                 hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2588                 if (!hash || IS_ERR(hash))
2589                         goto out_free;
2590
2591                 p->md5_desc.tfm = hash;
2592         }
2593         return pool;
2594 out_free:
2595         __tcp_free_md5sig_pool(pool);
2596         return NULL;
2597 }
2598
2599 struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(void)
2600 {
2601         struct tcp_md5sig_pool **pool;
2602         int alloc = 0;
2603
2604 retry:
2605         spin_lock_bh(&tcp_md5sig_pool_lock);
2606         pool = tcp_md5sig_pool;
2607         if (tcp_md5sig_users++ == 0) {
2608                 alloc = 1;
2609                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2610         } else if (!pool) {
2611                 tcp_md5sig_users--;
2612                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2613                 cpu_relax();
2614                 goto retry;
2615         } else
2616                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2617
2618         if (alloc) {
2619                 /* we cannot hold spinlock here because this may sleep. */
2620                 struct tcp_md5sig_pool **p = __tcp_alloc_md5sig_pool();
2621                 spin_lock_bh(&tcp_md5sig_pool_lock);
2622                 if (!p) {
2623                         tcp_md5sig_users--;
2624                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2625                         return NULL;
2626                 }
2627                 pool = tcp_md5sig_pool;
2628                 if (pool) {
2629                         /* oops, it has already been assigned. */
2630                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2631                         __tcp_free_md5sig_pool(p);
2632                 } else {
2633                         tcp_md5sig_pool = pool = p;
2634                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2635                 }
2636         }
2637         return pool;
2638 }
2639
2640 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2641
2642 struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu)
2643 {
2644         struct tcp_md5sig_pool **p;
2645         spin_lock_bh(&tcp_md5sig_pool_lock);
2646         p = tcp_md5sig_pool;
2647         if (p)
2648                 tcp_md5sig_users++;
2649         spin_unlock_bh(&tcp_md5sig_pool_lock);
2650         return (p ? *per_cpu_ptr(p, cpu) : NULL);
2651 }
2652
2653 EXPORT_SYMBOL(__tcp_get_md5sig_pool);
2654
2655 void __tcp_put_md5sig_pool(void)
2656 {
2657         tcp_free_md5sig_pool();
2658 }
2659
2660 EXPORT_SYMBOL(__tcp_put_md5sig_pool);
2661 #endif
2662
2663 void tcp_done(struct sock *sk)
2664 {
2665         if(sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
2666                 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
2667
2668         tcp_set_state(sk, TCP_CLOSE);
2669         tcp_clear_xmit_timers(sk);
2670
2671         sk->sk_shutdown = SHUTDOWN_MASK;
2672
2673         if (!sock_flag(sk, SOCK_DEAD))
2674                 sk->sk_state_change(sk);
2675         else
2676                 inet_csk_destroy_sock(sk);
2677 }
2678 EXPORT_SYMBOL_GPL(tcp_done);
2679
2680 extern struct tcp_congestion_ops tcp_reno;
2681
2682 static __initdata unsigned long thash_entries;
2683 static int __init set_thash_entries(char *str)
2684 {
2685         if (!str)
2686                 return 0;
2687         thash_entries = simple_strtoul(str, &str, 0);
2688         return 1;
2689 }
2690 __setup("thash_entries=", set_thash_entries);
2691
2692 void __init tcp_init(void)
2693 {
2694         struct sk_buff *skb = NULL;
2695         unsigned long nr_pages, limit;
2696         int order, i, max_share;
2697
2698         BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
2699
2700         tcp_hashinfo.bind_bucket_cachep =
2701                 kmem_cache_create("tcp_bind_bucket",
2702                                   sizeof(struct inet_bind_bucket), 0,
2703                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2704
2705         /* Size and allocate the main established and bind bucket
2706          * hash tables.
2707          *
2708          * The methodology is similar to that of the buffer cache.
2709          */
2710         tcp_hashinfo.ehash =
2711                 alloc_large_system_hash("TCP established",
2712                                         sizeof(struct inet_ehash_bucket),
2713                                         thash_entries,
2714                                         (num_physpages >= 128 * 1024) ?
2715                                         13 : 15,
2716                                         0,
2717                                         &tcp_hashinfo.ehash_size,
2718                                         NULL,
2719                                         thash_entries ? 0 : 512 * 1024);
2720         tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size;
2721         for (i = 0; i < tcp_hashinfo.ehash_size; i++) {
2722                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
2723                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].twchain);
2724         }
2725         if (inet_ehash_locks_alloc(&tcp_hashinfo))
2726                 panic("TCP: failed to alloc ehash_locks");
2727         tcp_hashinfo.bhash =
2728                 alloc_large_system_hash("TCP bind",
2729                                         sizeof(struct inet_bind_hashbucket),
2730                                         tcp_hashinfo.ehash_size,
2731                                         (num_physpages >= 128 * 1024) ?
2732                                         13 : 15,
2733                                         0,
2734                                         &tcp_hashinfo.bhash_size,
2735                                         NULL,
2736                                         64 * 1024);
2737         tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
2738         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
2739                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
2740                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
2741         }
2742
2743         /* Try to be a bit smarter and adjust defaults depending
2744          * on available memory.
2745          */
2746         for (order = 0; ((1 << order) << PAGE_SHIFT) <
2747                         (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
2748                         order++)
2749                 ;
2750         if (order >= 4) {
2751                 tcp_death_row.sysctl_max_tw_buckets = 180000;
2752                 sysctl_tcp_max_orphans = 4096 << (order - 4);
2753                 sysctl_max_syn_backlog = 1024;
2754         } else if (order < 3) {
2755                 tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
2756                 sysctl_tcp_max_orphans >>= (3 - order);
2757                 sysctl_max_syn_backlog = 128;
2758         }
2759
2760         /* Set the pressure threshold to be a fraction of global memory that
2761          * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
2762          * memory, with a floor of 128 pages.
2763          */
2764         nr_pages = totalram_pages - totalhigh_pages;
2765         limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
2766         limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
2767         limit = max(limit, 128UL);
2768         sysctl_tcp_mem[0] = limit / 4 * 3;
2769         sysctl_tcp_mem[1] = limit;
2770         sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
2771
2772         /* Set per-socket limits to no more than 1/128 the pressure threshold */
2773         limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
2774         max_share = min(4UL*1024*1024, limit);
2775
2776         sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
2777         sysctl_tcp_wmem[1] = 16*1024;
2778         sysctl_tcp_wmem[2] = max(64*1024, max_share);
2779
2780         sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
2781         sysctl_tcp_rmem[1] = 87380;
2782         sysctl_tcp_rmem[2] = max(87380, max_share);
2783
2784         printk(KERN_INFO "TCP: Hash tables configured "
2785                "(established %d bind %d)\n",
2786                tcp_hashinfo.ehash_size, tcp_hashinfo.bhash_size);
2787
2788         tcp_register_congestion_control(&tcp_reno);
2789 }
2790
2791 EXPORT_SYMBOL(tcp_close);
2792 EXPORT_SYMBOL(tcp_disconnect);
2793 EXPORT_SYMBOL(tcp_getsockopt);
2794 EXPORT_SYMBOL(tcp_ioctl);
2795 EXPORT_SYMBOL(tcp_poll);
2796 EXPORT_SYMBOL(tcp_read_sock);
2797 EXPORT_SYMBOL(tcp_recvmsg);
2798 EXPORT_SYMBOL(tcp_sendmsg);
2799 EXPORT_SYMBOL(tcp_splice_read);
2800 EXPORT_SYMBOL(tcp_sendpage);
2801 EXPORT_SYMBOL(tcp_setsockopt);
2802 EXPORT_SYMBOL(tcp_shutdown);
2803 EXPORT_SYMBOL(tcp_statistics);