c259714c55961ffa74ec1f5c79b8b1cddb83132f
[sfrench/cifs-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 #include <linux/time.h>
268 #include <linux/slab.h>
269
270 #include <net/icmp.h>
271 #include <net/tcp.h>
272 #include <net/xfrm.h>
273 #include <net/ip.h>
274 #include <net/netdma.h>
275 #include <net/sock.h>
276
277 #include <asm/uaccess.h>
278 #include <asm/ioctls.h>
279
280 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
281
282 struct percpu_counter tcp_orphan_count;
283 EXPORT_SYMBOL_GPL(tcp_orphan_count);
284
285 int sysctl_tcp_mem[3] __read_mostly;
286 int sysctl_tcp_wmem[3] __read_mostly;
287 int sysctl_tcp_rmem[3] __read_mostly;
288
289 EXPORT_SYMBOL(sysctl_tcp_mem);
290 EXPORT_SYMBOL(sysctl_tcp_rmem);
291 EXPORT_SYMBOL(sysctl_tcp_wmem);
292
293 atomic_t tcp_memory_allocated;  /* Current allocated memory. */
294 EXPORT_SYMBOL(tcp_memory_allocated);
295
296 /*
297  * Current number of TCP sockets.
298  */
299 struct percpu_counter tcp_sockets_allocated;
300 EXPORT_SYMBOL(tcp_sockets_allocated);
301
302 /*
303  * TCP splice context
304  */
305 struct tcp_splice_state {
306         struct pipe_inode_info *pipe;
307         size_t len;
308         unsigned int flags;
309 };
310
311 /*
312  * Pressure flag: try to collapse.
313  * Technical note: it is used by multiple contexts non atomically.
314  * All the __sk_mem_schedule() is of this nature: accounting
315  * is strict, actions are advisory and have some latency.
316  */
317 int tcp_memory_pressure __read_mostly;
318
319 EXPORT_SYMBOL(tcp_memory_pressure);
320
321 void tcp_enter_memory_pressure(struct sock *sk)
322 {
323         if (!tcp_memory_pressure) {
324                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
325                 tcp_memory_pressure = 1;
326         }
327 }
328
329 EXPORT_SYMBOL(tcp_enter_memory_pressure);
330
331 /* Convert seconds to retransmits based on initial and max timeout */
332 static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
333 {
334         u8 res = 0;
335
336         if (seconds > 0) {
337                 int period = timeout;
338
339                 res = 1;
340                 while (seconds > period && res < 255) {
341                         res++;
342                         timeout <<= 1;
343                         if (timeout > rto_max)
344                                 timeout = rto_max;
345                         period += timeout;
346                 }
347         }
348         return res;
349 }
350
351 /* Convert retransmits to seconds based on initial and max timeout */
352 static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
353 {
354         int period = 0;
355
356         if (retrans > 0) {
357                 period = timeout;
358                 while (--retrans) {
359                         timeout <<= 1;
360                         if (timeout > rto_max)
361                                 timeout = rto_max;
362                         period += timeout;
363                 }
364         }
365         return period;
366 }
367
368 /*
369  *      Wait for a TCP event.
370  *
371  *      Note that we don't need to lock the socket, as the upper poll layers
372  *      take care of normal races (between the test and the event) and we don't
373  *      go look at any of the socket buffers directly.
374  */
375 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
376 {
377         unsigned int mask;
378         struct sock *sk = sock->sk;
379         struct tcp_sock *tp = tcp_sk(sk);
380
381         sock_poll_wait(file, sk_sleep(sk), wait);
382         if (sk->sk_state == TCP_LISTEN)
383                 return inet_csk_listen_poll(sk);
384
385         /* Socket is not locked. We are protected from async events
386          * by poll logic and correct handling of state changes
387          * made by other threads is impossible in any case.
388          */
389
390         mask = 0;
391         if (sk->sk_err)
392                 mask = POLLERR;
393
394         /*
395          * POLLHUP is certainly not done right. But poll() doesn't
396          * have a notion of HUP in just one direction, and for a
397          * socket the read side is more interesting.
398          *
399          * Some poll() documentation says that POLLHUP is incompatible
400          * with the POLLOUT/POLLWR flags, so somebody should check this
401          * all. But careful, it tends to be safer to return too many
402          * bits than too few, and you can easily break real applications
403          * if you don't tell them that something has hung up!
404          *
405          * Check-me.
406          *
407          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
408          * our fs/select.c). It means that after we received EOF,
409          * poll always returns immediately, making impossible poll() on write()
410          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
411          * if and only if shutdown has been made in both directions.
412          * Actually, it is interesting to look how Solaris and DUX
413          * solve this dilemma. I would prefer, if POLLHUP were maskable,
414          * then we could set it on SND_SHUTDOWN. BTW examples given
415          * in Stevens' books assume exactly this behaviour, it explains
416          * why POLLHUP is incompatible with POLLOUT.    --ANK
417          *
418          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
419          * blocking on fresh not-connected or disconnected socket. --ANK
420          */
421         if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
422                 mask |= POLLHUP;
423         if (sk->sk_shutdown & RCV_SHUTDOWN)
424                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
425
426         /* Connected? */
427         if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
428                 int target = sock_rcvlowat(sk, 0, INT_MAX);
429
430                 if (tp->urg_seq == tp->copied_seq &&
431                     !sock_flag(sk, SOCK_URGINLINE) &&
432                     tp->urg_data)
433                         target++;
434
435                 /* Potential race condition. If read of tp below will
436                  * escape above sk->sk_state, we can be illegally awaken
437                  * in SYN_* states. */
438                 if (tp->rcv_nxt - tp->copied_seq >= target)
439                         mask |= POLLIN | POLLRDNORM;
440
441                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
442                         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
443                                 mask |= POLLOUT | POLLWRNORM;
444                         } else {  /* send SIGIO later */
445                                 set_bit(SOCK_ASYNC_NOSPACE,
446                                         &sk->sk_socket->flags);
447                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
448
449                                 /* Race breaker. If space is freed after
450                                  * wspace test but before the flags are set,
451                                  * IO signal will be lost.
452                                  */
453                                 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
454                                         mask |= POLLOUT | POLLWRNORM;
455                         }
456                 }
457
458                 if (tp->urg_data & TCP_URG_VALID)
459                         mask |= POLLPRI;
460         }
461         return mask;
462 }
463
464 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
465 {
466         struct tcp_sock *tp = tcp_sk(sk);
467         int answ;
468
469         switch (cmd) {
470         case SIOCINQ:
471                 if (sk->sk_state == TCP_LISTEN)
472                         return -EINVAL;
473
474                 lock_sock(sk);
475                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
476                         answ = 0;
477                 else if (sock_flag(sk, SOCK_URGINLINE) ||
478                          !tp->urg_data ||
479                          before(tp->urg_seq, tp->copied_seq) ||
480                          !before(tp->urg_seq, tp->rcv_nxt)) {
481                         struct sk_buff *skb;
482
483                         answ = tp->rcv_nxt - tp->copied_seq;
484
485                         /* Subtract 1, if FIN is in queue. */
486                         skb = skb_peek_tail(&sk->sk_receive_queue);
487                         if (answ && skb)
488                                 answ -= tcp_hdr(skb)->fin;
489                 } else
490                         answ = tp->urg_seq - tp->copied_seq;
491                 release_sock(sk);
492                 break;
493         case SIOCATMARK:
494                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
495                 break;
496         case SIOCOUTQ:
497                 if (sk->sk_state == TCP_LISTEN)
498                         return -EINVAL;
499
500                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
501                         answ = 0;
502                 else
503                         answ = tp->write_seq - tp->snd_una;
504                 break;
505         default:
506                 return -ENOIOCTLCMD;
507         }
508
509         return put_user(answ, (int __user *)arg);
510 }
511
512 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
513 {
514         TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
515         tp->pushed_seq = tp->write_seq;
516 }
517
518 static inline int forced_push(struct tcp_sock *tp)
519 {
520         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
521 }
522
523 static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
524 {
525         struct tcp_sock *tp = tcp_sk(sk);
526         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
527
528         skb->csum    = 0;
529         tcb->seq     = tcb->end_seq = tp->write_seq;
530         tcb->flags   = TCPCB_FLAG_ACK;
531         tcb->sacked  = 0;
532         skb_header_release(skb);
533         tcp_add_write_queue_tail(sk, skb);
534         sk->sk_wmem_queued += skb->truesize;
535         sk_mem_charge(sk, skb->truesize);
536         if (tp->nonagle & TCP_NAGLE_PUSH)
537                 tp->nonagle &= ~TCP_NAGLE_PUSH;
538 }
539
540 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
541 {
542         if (flags & MSG_OOB)
543                 tp->snd_up = tp->write_seq;
544 }
545
546 static inline void tcp_push(struct sock *sk, int flags, int mss_now,
547                             int nonagle)
548 {
549         if (tcp_send_head(sk)) {
550                 struct tcp_sock *tp = tcp_sk(sk);
551
552                 if (!(flags & MSG_MORE) || forced_push(tp))
553                         tcp_mark_push(tp, tcp_write_queue_tail(sk));
554
555                 tcp_mark_urg(tp, flags);
556                 __tcp_push_pending_frames(sk, mss_now,
557                                           (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
558         }
559 }
560
561 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
562                                 unsigned int offset, size_t len)
563 {
564         struct tcp_splice_state *tss = rd_desc->arg.data;
565         int ret;
566
567         ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len),
568                               tss->flags);
569         if (ret > 0)
570                 rd_desc->count -= ret;
571         return ret;
572 }
573
574 static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
575 {
576         /* Store TCP splice context information in read_descriptor_t. */
577         read_descriptor_t rd_desc = {
578                 .arg.data = tss,
579                 .count    = tss->len,
580         };
581
582         return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
583 }
584
585 /**
586  *  tcp_splice_read - splice data from TCP socket to a pipe
587  * @sock:       socket to splice from
588  * @ppos:       position (not valid)
589  * @pipe:       pipe to splice to
590  * @len:        number of bytes to splice
591  * @flags:      splice modifier flags
592  *
593  * Description:
594  *    Will read pages from given socket and fill them into a pipe.
595  *
596  **/
597 ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
598                         struct pipe_inode_info *pipe, size_t len,
599                         unsigned int flags)
600 {
601         struct sock *sk = sock->sk;
602         struct tcp_splice_state tss = {
603                 .pipe = pipe,
604                 .len = len,
605                 .flags = flags,
606         };
607         long timeo;
608         ssize_t spliced;
609         int ret;
610
611         sock_rps_record_flow(sk);
612         /*
613          * We can't seek on a socket input
614          */
615         if (unlikely(*ppos))
616                 return -ESPIPE;
617
618         ret = spliced = 0;
619
620         lock_sock(sk);
621
622         timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
623         while (tss.len) {
624                 ret = __tcp_splice_read(sk, &tss);
625                 if (ret < 0)
626                         break;
627                 else if (!ret) {
628                         if (spliced)
629                                 break;
630                         if (sock_flag(sk, SOCK_DONE))
631                                 break;
632                         if (sk->sk_err) {
633                                 ret = sock_error(sk);
634                                 break;
635                         }
636                         if (sk->sk_shutdown & RCV_SHUTDOWN)
637                                 break;
638                         if (sk->sk_state == TCP_CLOSE) {
639                                 /*
640                                  * This occurs when user tries to read
641                                  * from never connected socket.
642                                  */
643                                 if (!sock_flag(sk, SOCK_DONE))
644                                         ret = -ENOTCONN;
645                                 break;
646                         }
647                         if (!timeo) {
648                                 ret = -EAGAIN;
649                                 break;
650                         }
651                         sk_wait_data(sk, &timeo);
652                         if (signal_pending(current)) {
653                                 ret = sock_intr_errno(timeo);
654                                 break;
655                         }
656                         continue;
657                 }
658                 tss.len -= ret;
659                 spliced += ret;
660
661                 if (!timeo)
662                         break;
663                 release_sock(sk);
664                 lock_sock(sk);
665
666                 if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
667                     (sk->sk_shutdown & RCV_SHUTDOWN) ||
668                     signal_pending(current))
669                         break;
670         }
671
672         release_sock(sk);
673
674         if (spliced)
675                 return spliced;
676
677         return ret;
678 }
679
680 struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
681 {
682         struct sk_buff *skb;
683
684         /* The TCP header must be at least 32-bit aligned.  */
685         size = ALIGN(size, 4);
686
687         skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
688         if (skb) {
689                 if (sk_wmem_schedule(sk, skb->truesize)) {
690                         /*
691                          * Make sure that we have exactly size bytes
692                          * available to the caller, no more, no less.
693                          */
694                         skb_reserve(skb, skb_tailroom(skb) - size);
695                         return skb;
696                 }
697                 __kfree_skb(skb);
698         } else {
699                 sk->sk_prot->enter_memory_pressure(sk);
700                 sk_stream_moderate_sndbuf(sk);
701         }
702         return NULL;
703 }
704
705 static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
706                                        int large_allowed)
707 {
708         struct tcp_sock *tp = tcp_sk(sk);
709         u32 xmit_size_goal, old_size_goal;
710
711         xmit_size_goal = mss_now;
712
713         if (large_allowed && sk_can_gso(sk)) {
714                 xmit_size_goal = ((sk->sk_gso_max_size - 1) -
715                                   inet_csk(sk)->icsk_af_ops->net_header_len -
716                                   inet_csk(sk)->icsk_ext_hdr_len -
717                                   tp->tcp_header_len);
718
719                 xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);
720
721                 /* We try hard to avoid divides here */
722                 old_size_goal = tp->xmit_size_goal_segs * mss_now;
723
724                 if (likely(old_size_goal <= xmit_size_goal &&
725                            old_size_goal + mss_now > xmit_size_goal)) {
726                         xmit_size_goal = old_size_goal;
727                 } else {
728                         tp->xmit_size_goal_segs = xmit_size_goal / mss_now;
729                         xmit_size_goal = tp->xmit_size_goal_segs * mss_now;
730                 }
731         }
732
733         return max(xmit_size_goal, mss_now);
734 }
735
736 static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
737 {
738         int mss_now;
739
740         mss_now = tcp_current_mss(sk);
741         *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
742
743         return mss_now;
744 }
745
746 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
747                          size_t psize, int flags)
748 {
749         struct tcp_sock *tp = tcp_sk(sk);
750         int mss_now, size_goal;
751         int err;
752         ssize_t copied;
753         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
754
755         /* Wait for a connection to finish. */
756         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
757                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
758                         goto out_err;
759
760         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
761
762         mss_now = tcp_send_mss(sk, &size_goal, flags);
763         copied = 0;
764
765         err = -EPIPE;
766         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
767                 goto out_err;
768
769         while (psize > 0) {
770                 struct sk_buff *skb = tcp_write_queue_tail(sk);
771                 struct page *page = pages[poffset / PAGE_SIZE];
772                 int copy, i, can_coalesce;
773                 int offset = poffset % PAGE_SIZE;
774                 int size = min_t(size_t, psize, PAGE_SIZE - offset);
775
776                 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
777 new_segment:
778                         if (!sk_stream_memory_free(sk))
779                                 goto wait_for_sndbuf;
780
781                         skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
782                         if (!skb)
783                                 goto wait_for_memory;
784
785                         skb_entail(sk, skb);
786                         copy = size_goal;
787                 }
788
789                 if (copy > size)
790                         copy = size;
791
792                 i = skb_shinfo(skb)->nr_frags;
793                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
794                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
795                         tcp_mark_push(tp, skb);
796                         goto new_segment;
797                 }
798                 if (!sk_wmem_schedule(sk, copy))
799                         goto wait_for_memory;
800
801                 if (can_coalesce) {
802                         skb_shinfo(skb)->frags[i - 1].size += copy;
803                 } else {
804                         get_page(page);
805                         skb_fill_page_desc(skb, i, page, offset, copy);
806                 }
807
808                 skb->len += copy;
809                 skb->data_len += copy;
810                 skb->truesize += copy;
811                 sk->sk_wmem_queued += copy;
812                 sk_mem_charge(sk, copy);
813                 skb->ip_summed = CHECKSUM_PARTIAL;
814                 tp->write_seq += copy;
815                 TCP_SKB_CB(skb)->end_seq += copy;
816                 skb_shinfo(skb)->gso_segs = 0;
817
818                 if (!copied)
819                         TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
820
821                 copied += copy;
822                 poffset += copy;
823                 if (!(psize -= copy))
824                         goto out;
825
826                 if (skb->len < size_goal || (flags & MSG_OOB))
827                         continue;
828
829                 if (forced_push(tp)) {
830                         tcp_mark_push(tp, skb);
831                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
832                 } else if (skb == tcp_send_head(sk))
833                         tcp_push_one(sk, mss_now);
834                 continue;
835
836 wait_for_sndbuf:
837                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
838 wait_for_memory:
839                 if (copied)
840                         tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
841
842                 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
843                         goto do_error;
844
845                 mss_now = tcp_send_mss(sk, &size_goal, flags);
846         }
847
848 out:
849         if (copied)
850                 tcp_push(sk, flags, mss_now, tp->nonagle);
851         return copied;
852
853 do_error:
854         if (copied)
855                 goto out;
856 out_err:
857         return sk_stream_error(sk, flags, err);
858 }
859
860 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
861                      size_t size, int flags)
862 {
863         ssize_t res;
864         struct sock *sk = sock->sk;
865
866         if (!(sk->sk_route_caps & NETIF_F_SG) ||
867             !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
868                 return sock_no_sendpage(sock, page, offset, size, flags);
869
870         lock_sock(sk);
871         TCP_CHECK_TIMER(sk);
872         res = do_tcp_sendpages(sk, &page, offset, size, flags);
873         TCP_CHECK_TIMER(sk);
874         release_sock(sk);
875         return res;
876 }
877
878 #define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
879 #define TCP_OFF(sk)     (sk->sk_sndmsg_off)
880
881 static inline int select_size(struct sock *sk, int sg)
882 {
883         struct tcp_sock *tp = tcp_sk(sk);
884         int tmp = tp->mss_cache;
885
886         if (sg) {
887                 if (sk_can_gso(sk))
888                         tmp = 0;
889                 else {
890                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
891
892                         if (tmp >= pgbreak &&
893                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
894                                 tmp = pgbreak;
895                 }
896         }
897
898         return tmp;
899 }
900
901 int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
902                 size_t size)
903 {
904         struct sock *sk = sock->sk;
905         struct iovec *iov;
906         struct tcp_sock *tp = tcp_sk(sk);
907         struct sk_buff *skb;
908         int iovlen, flags;
909         int mss_now, size_goal;
910         int sg, err, copied;
911         long timeo;
912
913         lock_sock(sk);
914         TCP_CHECK_TIMER(sk);
915
916         flags = msg->msg_flags;
917         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
918
919         /* Wait for a connection to finish. */
920         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
921                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
922                         goto out_err;
923
924         /* This should be in poll */
925         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
926
927         mss_now = tcp_send_mss(sk, &size_goal, flags);
928
929         /* Ok commence sending. */
930         iovlen = msg->msg_iovlen;
931         iov = msg->msg_iov;
932         copied = 0;
933
934         err = -EPIPE;
935         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
936                 goto out_err;
937
938         sg = sk->sk_route_caps & NETIF_F_SG;
939
940         while (--iovlen >= 0) {
941                 int seglen = iov->iov_len;
942                 unsigned char __user *from = iov->iov_base;
943
944                 iov++;
945
946                 while (seglen > 0) {
947                         int copy = 0;
948                         int max = size_goal;
949
950                         skb = tcp_write_queue_tail(sk);
951                         if (tcp_send_head(sk)) {
952                                 if (skb->ip_summed == CHECKSUM_NONE)
953                                         max = mss_now;
954                                 copy = max - skb->len;
955                         }
956
957                         if (copy <= 0) {
958 new_segment:
959                                 /* Allocate new segment. If the interface is SG,
960                                  * allocate skb fitting to single page.
961                                  */
962                                 if (!sk_stream_memory_free(sk))
963                                         goto wait_for_sndbuf;
964
965                                 skb = sk_stream_alloc_skb(sk,
966                                                           select_size(sk, sg),
967                                                           sk->sk_allocation);
968                                 if (!skb)
969                                         goto wait_for_memory;
970
971                                 /*
972                                  * Check whether we can use HW checksum.
973                                  */
974                                 if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
975                                         skb->ip_summed = CHECKSUM_PARTIAL;
976
977                                 skb_entail(sk, skb);
978                                 copy = size_goal;
979                                 max = size_goal;
980                         }
981
982                         /* Try to append data to the end of skb. */
983                         if (copy > seglen)
984                                 copy = seglen;
985
986                         /* Where to copy to? */
987                         if (skb_tailroom(skb) > 0) {
988                                 /* We have some space in skb head. Superb! */
989                                 if (copy > skb_tailroom(skb))
990                                         copy = skb_tailroom(skb);
991                                 if ((err = skb_add_data(skb, from, copy)) != 0)
992                                         goto do_fault;
993                         } else {
994                                 int merge = 0;
995                                 int i = skb_shinfo(skb)->nr_frags;
996                                 struct page *page = TCP_PAGE(sk);
997                                 int off = TCP_OFF(sk);
998
999                                 if (skb_can_coalesce(skb, i, page, off) &&
1000                                     off != PAGE_SIZE) {
1001                                         /* We can extend the last page
1002                                          * fragment. */
1003                                         merge = 1;
1004                                 } else if (i == MAX_SKB_FRAGS || !sg) {
1005                                         /* Need to add new fragment and cannot
1006                                          * do this because interface is non-SG,
1007                                          * or because all the page slots are
1008                                          * busy. */
1009                                         tcp_mark_push(tp, skb);
1010                                         goto new_segment;
1011                                 } else if (page) {
1012                                         if (off == PAGE_SIZE) {
1013                                                 put_page(page);
1014                                                 TCP_PAGE(sk) = page = NULL;
1015                                                 off = 0;
1016                                         }
1017                                 } else
1018                                         off = 0;
1019
1020                                 if (copy > PAGE_SIZE - off)
1021                                         copy = PAGE_SIZE - off;
1022
1023                                 if (!sk_wmem_schedule(sk, copy))
1024                                         goto wait_for_memory;
1025
1026                                 if (!page) {
1027                                         /* Allocate new cache page. */
1028                                         if (!(page = sk_stream_alloc_page(sk)))
1029                                                 goto wait_for_memory;
1030                                 }
1031
1032                                 /* Time to copy data. We are close to
1033                                  * the end! */
1034                                 err = skb_copy_to_page(sk, from, skb, page,
1035                                                        off, copy);
1036                                 if (err) {
1037                                         /* If this page was new, give it to the
1038                                          * socket so it does not get leaked.
1039                                          */
1040                                         if (!TCP_PAGE(sk)) {
1041                                                 TCP_PAGE(sk) = page;
1042                                                 TCP_OFF(sk) = 0;
1043                                         }
1044                                         goto do_error;
1045                                 }
1046
1047                                 /* Update the skb. */
1048                                 if (merge) {
1049                                         skb_shinfo(skb)->frags[i - 1].size +=
1050                                                                         copy;
1051                                 } else {
1052                                         skb_fill_page_desc(skb, i, page, off, copy);
1053                                         if (TCP_PAGE(sk)) {
1054                                                 get_page(page);
1055                                         } else if (off + copy < PAGE_SIZE) {
1056                                                 get_page(page);
1057                                                 TCP_PAGE(sk) = page;
1058                                         }
1059                                 }
1060
1061                                 TCP_OFF(sk) = off + copy;
1062                         }
1063
1064                         if (!copied)
1065                                 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
1066
1067                         tp->write_seq += copy;
1068                         TCP_SKB_CB(skb)->end_seq += copy;
1069                         skb_shinfo(skb)->gso_segs = 0;
1070
1071                         from += copy;
1072                         copied += copy;
1073                         if ((seglen -= copy) == 0 && iovlen == 0)
1074                                 goto out;
1075
1076                         if (skb->len < max || (flags & MSG_OOB))
1077                                 continue;
1078
1079                         if (forced_push(tp)) {
1080                                 tcp_mark_push(tp, skb);
1081                                 __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1082                         } else if (skb == tcp_send_head(sk))
1083                                 tcp_push_one(sk, mss_now);
1084                         continue;
1085
1086 wait_for_sndbuf:
1087                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1088 wait_for_memory:
1089                         if (copied)
1090                                 tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
1091
1092                         if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
1093                                 goto do_error;
1094
1095                         mss_now = tcp_send_mss(sk, &size_goal, flags);
1096                 }
1097         }
1098
1099 out:
1100         if (copied)
1101                 tcp_push(sk, flags, mss_now, tp->nonagle);
1102         TCP_CHECK_TIMER(sk);
1103         release_sock(sk);
1104         return copied;
1105
1106 do_fault:
1107         if (!skb->len) {
1108                 tcp_unlink_write_queue(skb, sk);
1109                 /* It is the one place in all of TCP, except connection
1110                  * reset, where we can be unlinking the send_head.
1111                  */
1112                 tcp_check_send_head(sk, skb);
1113                 sk_wmem_free_skb(sk, skb);
1114         }
1115
1116 do_error:
1117         if (copied)
1118                 goto out;
1119 out_err:
1120         err = sk_stream_error(sk, flags, err);
1121         TCP_CHECK_TIMER(sk);
1122         release_sock(sk);
1123         return err;
1124 }
1125
1126 /*
1127  *      Handle reading urgent data. BSD has very simple semantics for
1128  *      this, no blocking and very strange errors 8)
1129  */
1130
1131 static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1132 {
1133         struct tcp_sock *tp = tcp_sk(sk);
1134
1135         /* No URG data to read. */
1136         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1137             tp->urg_data == TCP_URG_READ)
1138                 return -EINVAL; /* Yes this is right ! */
1139
1140         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1141                 return -ENOTCONN;
1142
1143         if (tp->urg_data & TCP_URG_VALID) {
1144                 int err = 0;
1145                 char c = tp->urg_data;
1146
1147                 if (!(flags & MSG_PEEK))
1148                         tp->urg_data = TCP_URG_READ;
1149
1150                 /* Read urgent data. */
1151                 msg->msg_flags |= MSG_OOB;
1152
1153                 if (len > 0) {
1154                         if (!(flags & MSG_TRUNC))
1155                                 err = memcpy_toiovec(msg->msg_iov, &c, 1);
1156                         len = 1;
1157                 } else
1158                         msg->msg_flags |= MSG_TRUNC;
1159
1160                 return err ? -EFAULT : len;
1161         }
1162
1163         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1164                 return 0;
1165
1166         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1167          * the available implementations agree in this case:
1168          * this call should never block, independent of the
1169          * blocking state of the socket.
1170          * Mike <pall@rz.uni-karlsruhe.de>
1171          */
1172         return -EAGAIN;
1173 }
1174
1175 /* Clean up the receive buffer for full frames taken by the user,
1176  * then send an ACK if necessary.  COPIED is the number of bytes
1177  * tcp_recvmsg has given to the user so far, it speeds up the
1178  * calculation of whether or not we must ACK for the sake of
1179  * a window update.
1180  */
1181 void tcp_cleanup_rbuf(struct sock *sk, int copied)
1182 {
1183         struct tcp_sock *tp = tcp_sk(sk);
1184         int time_to_ack = 0;
1185
1186 #if TCP_DEBUG
1187         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1188
1189         WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1190              KERN_INFO "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1191              tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1192 #endif
1193
1194         if (inet_csk_ack_scheduled(sk)) {
1195                 const struct inet_connection_sock *icsk = inet_csk(sk);
1196                    /* Delayed ACKs frequently hit locked sockets during bulk
1197                     * receive. */
1198                 if (icsk->icsk_ack.blocked ||
1199                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
1200                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1201                     /*
1202                      * If this read emptied read buffer, we send ACK, if
1203                      * connection is not bidirectional, user drained
1204                      * receive buffer and there was a small segment
1205                      * in queue.
1206                      */
1207                     (copied > 0 &&
1208                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1209                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1210                        !icsk->icsk_ack.pingpong)) &&
1211                       !atomic_read(&sk->sk_rmem_alloc)))
1212                         time_to_ack = 1;
1213         }
1214
1215         /* We send an ACK if we can now advertise a non-zero window
1216          * which has been raised "significantly".
1217          *
1218          * Even if window raised up to infinity, do not send window open ACK
1219          * in states, where we will not receive more. It is useless.
1220          */
1221         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1222                 __u32 rcv_window_now = tcp_receive_window(tp);
1223
1224                 /* Optimize, __tcp_select_window() is not cheap. */
1225                 if (2*rcv_window_now <= tp->window_clamp) {
1226                         __u32 new_window = __tcp_select_window(sk);
1227
1228                         /* Send ACK now, if this read freed lots of space
1229                          * in our buffer. Certainly, new_window is new window.
1230                          * We can advertise it now, if it is not less than current one.
1231                          * "Lots" means "at least twice" here.
1232                          */
1233                         if (new_window && new_window >= 2 * rcv_window_now)
1234                                 time_to_ack = 1;
1235                 }
1236         }
1237         if (time_to_ack)
1238                 tcp_send_ack(sk);
1239 }
1240
1241 static void tcp_prequeue_process(struct sock *sk)
1242 {
1243         struct sk_buff *skb;
1244         struct tcp_sock *tp = tcp_sk(sk);
1245
1246         NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1247
1248         /* RX process wants to run with disabled BHs, though it is not
1249          * necessary */
1250         local_bh_disable();
1251         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1252                 sk_backlog_rcv(sk, skb);
1253         local_bh_enable();
1254
1255         /* Clear memory counter. */
1256         tp->ucopy.memory = 0;
1257 }
1258
1259 #ifdef CONFIG_NET_DMA
1260 static void tcp_service_net_dma(struct sock *sk, bool wait)
1261 {
1262         dma_cookie_t done, used;
1263         dma_cookie_t last_issued;
1264         struct tcp_sock *tp = tcp_sk(sk);
1265
1266         if (!tp->ucopy.dma_chan)
1267                 return;
1268
1269         last_issued = tp->ucopy.dma_cookie;
1270         dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1271
1272         do {
1273                 if (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1274                                               last_issued, &done,
1275                                               &used) == DMA_SUCCESS) {
1276                         /* Safe to free early-copied skbs now */
1277                         __skb_queue_purge(&sk->sk_async_wait_queue);
1278                         break;
1279                 } else {
1280                         struct sk_buff *skb;
1281                         while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1282                                (dma_async_is_complete(skb->dma_cookie, done,
1283                                                       used) == DMA_SUCCESS)) {
1284                                 __skb_dequeue(&sk->sk_async_wait_queue);
1285                                 kfree_skb(skb);
1286                         }
1287                 }
1288         } while (wait);
1289 }
1290 #endif
1291
1292 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1293 {
1294         struct sk_buff *skb;
1295         u32 offset;
1296
1297         skb_queue_walk(&sk->sk_receive_queue, skb) {
1298                 offset = seq - TCP_SKB_CB(skb)->seq;
1299                 if (tcp_hdr(skb)->syn)
1300                         offset--;
1301                 if (offset < skb->len || tcp_hdr(skb)->fin) {
1302                         *off = offset;
1303                         return skb;
1304                 }
1305         }
1306         return NULL;
1307 }
1308
1309 /*
1310  * This routine provides an alternative to tcp_recvmsg() for routines
1311  * that would like to handle copying from skbuffs directly in 'sendfile'
1312  * fashion.
1313  * Note:
1314  *      - It is assumed that the socket was locked by the caller.
1315  *      - The routine does not block.
1316  *      - At present, there is no support for reading OOB data
1317  *        or for 'peeking' the socket using this routine
1318  *        (although both would be easy to implement).
1319  */
1320 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1321                   sk_read_actor_t recv_actor)
1322 {
1323         struct sk_buff *skb;
1324         struct tcp_sock *tp = tcp_sk(sk);
1325         u32 seq = tp->copied_seq;
1326         u32 offset;
1327         int copied = 0;
1328
1329         if (sk->sk_state == TCP_LISTEN)
1330                 return -ENOTCONN;
1331         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1332                 if (offset < skb->len) {
1333                         int used;
1334                         size_t len;
1335
1336                         len = skb->len - offset;
1337                         /* Stop reading if we hit a patch of urgent data */
1338                         if (tp->urg_data) {
1339                                 u32 urg_offset = tp->urg_seq - seq;
1340                                 if (urg_offset < len)
1341                                         len = urg_offset;
1342                                 if (!len)
1343                                         break;
1344                         }
1345                         used = recv_actor(desc, skb, offset, len);
1346                         if (used < 0) {
1347                                 if (!copied)
1348                                         copied = used;
1349                                 break;
1350                         } else if (used <= len) {
1351                                 seq += used;
1352                                 copied += used;
1353                                 offset += used;
1354                         }
1355                         /*
1356                          * If recv_actor drops the lock (e.g. TCP splice
1357                          * receive) the skb pointer might be invalid when
1358                          * getting here: tcp_collapse might have deleted it
1359                          * while aggregating skbs from the socket queue.
1360                          */
1361                         skb = tcp_recv_skb(sk, seq-1, &offset);
1362                         if (!skb || (offset+1 != skb->len))
1363                                 break;
1364                 }
1365                 if (tcp_hdr(skb)->fin) {
1366                         sk_eat_skb(sk, skb, 0);
1367                         ++seq;
1368                         break;
1369                 }
1370                 sk_eat_skb(sk, skb, 0);
1371                 if (!desc->count)
1372                         break;
1373                 tp->copied_seq = seq;
1374         }
1375         tp->copied_seq = seq;
1376
1377         tcp_rcv_space_adjust(sk);
1378
1379         /* Clean up data we have read: This will do ACK frames. */
1380         if (copied > 0)
1381                 tcp_cleanup_rbuf(sk, copied);
1382         return copied;
1383 }
1384
1385 /*
1386  *      This routine copies from a sock struct into the user buffer.
1387  *
1388  *      Technical note: in 2.3 we work on _locked_ socket, so that
1389  *      tricks with *seq access order and skb->users are not required.
1390  *      Probably, code can be easily improved even more.
1391  */
1392
1393 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1394                 size_t len, int nonblock, int flags, int *addr_len)
1395 {
1396         struct tcp_sock *tp = tcp_sk(sk);
1397         int copied = 0;
1398         u32 peek_seq;
1399         u32 *seq;
1400         unsigned long used;
1401         int err;
1402         int target;             /* Read at least this many bytes */
1403         long timeo;
1404         struct task_struct *user_recv = NULL;
1405         int copied_early = 0;
1406         struct sk_buff *skb;
1407         u32 urg_hole = 0;
1408
1409         lock_sock(sk);
1410
1411         TCP_CHECK_TIMER(sk);
1412
1413         err = -ENOTCONN;
1414         if (sk->sk_state == TCP_LISTEN)
1415                 goto out;
1416
1417         timeo = sock_rcvtimeo(sk, nonblock);
1418
1419         /* Urgent data needs to be handled specially. */
1420         if (flags & MSG_OOB)
1421                 goto recv_urg;
1422
1423         seq = &tp->copied_seq;
1424         if (flags & MSG_PEEK) {
1425                 peek_seq = tp->copied_seq;
1426                 seq = &peek_seq;
1427         }
1428
1429         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1430
1431 #ifdef CONFIG_NET_DMA
1432         tp->ucopy.dma_chan = NULL;
1433         preempt_disable();
1434         skb = skb_peek_tail(&sk->sk_receive_queue);
1435         {
1436                 int available = 0;
1437
1438                 if (skb)
1439                         available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
1440                 if ((available < target) &&
1441                     (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1442                     !sysctl_tcp_low_latency &&
1443                     dma_find_channel(DMA_MEMCPY)) {
1444                         preempt_enable_no_resched();
1445                         tp->ucopy.pinned_list =
1446                                         dma_pin_iovec_pages(msg->msg_iov, len);
1447                 } else {
1448                         preempt_enable_no_resched();
1449                 }
1450         }
1451 #endif
1452
1453         do {
1454                 u32 offset;
1455
1456                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1457                 if (tp->urg_data && tp->urg_seq == *seq) {
1458                         if (copied)
1459                                 break;
1460                         if (signal_pending(current)) {
1461                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1462                                 break;
1463                         }
1464                 }
1465
1466                 /* Next get a buffer. */
1467
1468                 skb_queue_walk(&sk->sk_receive_queue, skb) {
1469                         /* Now that we have two receive queues this
1470                          * shouldn't happen.
1471                          */
1472                         if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
1473                              KERN_INFO "recvmsg bug: copied %X "
1474                                        "seq %X rcvnxt %X fl %X\n", *seq,
1475                                        TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
1476                                        flags))
1477                                 break;
1478
1479                         offset = *seq - TCP_SKB_CB(skb)->seq;
1480                         if (tcp_hdr(skb)->syn)
1481                                 offset--;
1482                         if (offset < skb->len)
1483                                 goto found_ok_skb;
1484                         if (tcp_hdr(skb)->fin)
1485                                 goto found_fin_ok;
1486                         WARN(!(flags & MSG_PEEK), KERN_INFO "recvmsg bug 2: "
1487                                         "copied %X seq %X rcvnxt %X fl %X\n",
1488                                         *seq, TCP_SKB_CB(skb)->seq,
1489                                         tp->rcv_nxt, flags);
1490                 }
1491
1492                 /* Well, if we have backlog, try to process it now yet. */
1493
1494                 if (copied >= target && !sk->sk_backlog.tail)
1495                         break;
1496
1497                 if (copied) {
1498                         if (sk->sk_err ||
1499                             sk->sk_state == TCP_CLOSE ||
1500                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1501                             !timeo ||
1502                             signal_pending(current))
1503                                 break;
1504                 } else {
1505                         if (sock_flag(sk, SOCK_DONE))
1506                                 break;
1507
1508                         if (sk->sk_err) {
1509                                 copied = sock_error(sk);
1510                                 break;
1511                         }
1512
1513                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1514                                 break;
1515
1516                         if (sk->sk_state == TCP_CLOSE) {
1517                                 if (!sock_flag(sk, SOCK_DONE)) {
1518                                         /* This occurs when user tries to read
1519                                          * from never connected socket.
1520                                          */
1521                                         copied = -ENOTCONN;
1522                                         break;
1523                                 }
1524                                 break;
1525                         }
1526
1527                         if (!timeo) {
1528                                 copied = -EAGAIN;
1529                                 break;
1530                         }
1531
1532                         if (signal_pending(current)) {
1533                                 copied = sock_intr_errno(timeo);
1534                                 break;
1535                         }
1536                 }
1537
1538                 tcp_cleanup_rbuf(sk, copied);
1539
1540                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1541                         /* Install new reader */
1542                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1543                                 user_recv = current;
1544                                 tp->ucopy.task = user_recv;
1545                                 tp->ucopy.iov = msg->msg_iov;
1546                         }
1547
1548                         tp->ucopy.len = len;
1549
1550                         WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1551                                 !(flags & (MSG_PEEK | MSG_TRUNC)));
1552
1553                         /* Ugly... If prequeue is not empty, we have to
1554                          * process it before releasing socket, otherwise
1555                          * order will be broken at second iteration.
1556                          * More elegant solution is required!!!
1557                          *
1558                          * Look: we have the following (pseudo)queues:
1559                          *
1560                          * 1. packets in flight
1561                          * 2. backlog
1562                          * 3. prequeue
1563                          * 4. receive_queue
1564                          *
1565                          * Each queue can be processed only if the next ones
1566                          * are empty. At this point we have empty receive_queue.
1567                          * But prequeue _can_ be not empty after 2nd iteration,
1568                          * when we jumped to start of loop because backlog
1569                          * processing added something to receive_queue.
1570                          * We cannot release_sock(), because backlog contains
1571                          * packets arrived _after_ prequeued ones.
1572                          *
1573                          * Shortly, algorithm is clear --- to process all
1574                          * the queues in order. We could make it more directly,
1575                          * requeueing packets from backlog to prequeue, if
1576                          * is not empty. It is more elegant, but eats cycles,
1577                          * unfortunately.
1578                          */
1579                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1580                                 goto do_prequeue;
1581
1582                         /* __ Set realtime policy in scheduler __ */
1583                 }
1584
1585 #ifdef CONFIG_NET_DMA
1586                 if (tp->ucopy.dma_chan)
1587                         dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1588 #endif
1589                 if (copied >= target) {
1590                         /* Do not sleep, just process backlog. */
1591                         release_sock(sk);
1592                         lock_sock(sk);
1593                 } else
1594                         sk_wait_data(sk, &timeo);
1595
1596 #ifdef CONFIG_NET_DMA
1597                 tcp_service_net_dma(sk, false);  /* Don't block */
1598                 tp->ucopy.wakeup = 0;
1599 #endif
1600
1601                 if (user_recv) {
1602                         int chunk;
1603
1604                         /* __ Restore normal policy in scheduler __ */
1605
1606                         if ((chunk = len - tp->ucopy.len) != 0) {
1607                                 NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1608                                 len -= chunk;
1609                                 copied += chunk;
1610                         }
1611
1612                         if (tp->rcv_nxt == tp->copied_seq &&
1613                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1614 do_prequeue:
1615                                 tcp_prequeue_process(sk);
1616
1617                                 if ((chunk = len - tp->ucopy.len) != 0) {
1618                                         NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1619                                         len -= chunk;
1620                                         copied += chunk;
1621                                 }
1622                         }
1623                 }
1624                 if ((flags & MSG_PEEK) &&
1625                     (peek_seq - copied - urg_hole != tp->copied_seq)) {
1626                         if (net_ratelimit())
1627                                 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1628                                        current->comm, task_pid_nr(current));
1629                         peek_seq = tp->copied_seq;
1630                 }
1631                 continue;
1632
1633         found_ok_skb:
1634                 /* Ok so how much can we use? */
1635                 used = skb->len - offset;
1636                 if (len < used)
1637                         used = len;
1638
1639                 /* Do we have urgent data here? */
1640                 if (tp->urg_data) {
1641                         u32 urg_offset = tp->urg_seq - *seq;
1642                         if (urg_offset < used) {
1643                                 if (!urg_offset) {
1644                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1645                                                 ++*seq;
1646                                                 urg_hole++;
1647                                                 offset++;
1648                                                 used--;
1649                                                 if (!used)
1650                                                         goto skip_copy;
1651                                         }
1652                                 } else
1653                                         used = urg_offset;
1654                         }
1655                 }
1656
1657                 if (!(flags & MSG_TRUNC)) {
1658 #ifdef CONFIG_NET_DMA
1659                         if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1660                                 tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1661
1662                         if (tp->ucopy.dma_chan) {
1663                                 tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1664                                         tp->ucopy.dma_chan, skb, offset,
1665                                         msg->msg_iov, used,
1666                                         tp->ucopy.pinned_list);
1667
1668                                 if (tp->ucopy.dma_cookie < 0) {
1669
1670                                         printk(KERN_ALERT "dma_cookie < 0\n");
1671
1672                                         /* Exception. Bailout! */
1673                                         if (!copied)
1674                                                 copied = -EFAULT;
1675                                         break;
1676                                 }
1677
1678                                 dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1679
1680                                 if ((offset + used) == skb->len)
1681                                         copied_early = 1;
1682
1683                         } else
1684 #endif
1685                         {
1686                                 err = skb_copy_datagram_iovec(skb, offset,
1687                                                 msg->msg_iov, used);
1688                                 if (err) {
1689                                         /* Exception. Bailout! */
1690                                         if (!copied)
1691                                                 copied = -EFAULT;
1692                                         break;
1693                                 }
1694                         }
1695                 }
1696
1697                 *seq += used;
1698                 copied += used;
1699                 len -= used;
1700
1701                 tcp_rcv_space_adjust(sk);
1702
1703 skip_copy:
1704                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1705                         tp->urg_data = 0;
1706                         tcp_fast_path_check(sk);
1707                 }
1708                 if (used + offset < skb->len)
1709                         continue;
1710
1711                 if (tcp_hdr(skb)->fin)
1712                         goto found_fin_ok;
1713                 if (!(flags & MSG_PEEK)) {
1714                         sk_eat_skb(sk, skb, copied_early);
1715                         copied_early = 0;
1716                 }
1717                 continue;
1718
1719         found_fin_ok:
1720                 /* Process the FIN. */
1721                 ++*seq;
1722                 if (!(flags & MSG_PEEK)) {
1723                         sk_eat_skb(sk, skb, copied_early);
1724                         copied_early = 0;
1725                 }
1726                 break;
1727         } while (len > 0);
1728
1729         if (user_recv) {
1730                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1731                         int chunk;
1732
1733                         tp->ucopy.len = copied > 0 ? len : 0;
1734
1735                         tcp_prequeue_process(sk);
1736
1737                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1738                                 NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1739                                 len -= chunk;
1740                                 copied += chunk;
1741                         }
1742                 }
1743
1744                 tp->ucopy.task = NULL;
1745                 tp->ucopy.len = 0;
1746         }
1747
1748 #ifdef CONFIG_NET_DMA
1749         tcp_service_net_dma(sk, true);  /* Wait for queue to drain */
1750         tp->ucopy.dma_chan = NULL;
1751
1752         if (tp->ucopy.pinned_list) {
1753                 dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1754                 tp->ucopy.pinned_list = NULL;
1755         }
1756 #endif
1757
1758         /* According to UNIX98, msg_name/msg_namelen are ignored
1759          * on connected socket. I was just happy when found this 8) --ANK
1760          */
1761
1762         /* Clean up data we have read: This will do ACK frames. */
1763         tcp_cleanup_rbuf(sk, copied);
1764
1765         TCP_CHECK_TIMER(sk);
1766         release_sock(sk);
1767         return copied;
1768
1769 out:
1770         TCP_CHECK_TIMER(sk);
1771         release_sock(sk);
1772         return err;
1773
1774 recv_urg:
1775         err = tcp_recv_urg(sk, msg, len, flags);
1776         goto out;
1777 }
1778
1779 void tcp_set_state(struct sock *sk, int state)
1780 {
1781         int oldstate = sk->sk_state;
1782
1783         switch (state) {
1784         case TCP_ESTABLISHED:
1785                 if (oldstate != TCP_ESTABLISHED)
1786                         TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1787                 break;
1788
1789         case TCP_CLOSE:
1790                 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1791                         TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1792
1793                 sk->sk_prot->unhash(sk);
1794                 if (inet_csk(sk)->icsk_bind_hash &&
1795                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1796                         inet_put_port(sk);
1797                 /* fall through */
1798         default:
1799                 if (oldstate == TCP_ESTABLISHED)
1800                         TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1801         }
1802
1803         /* Change state AFTER socket is unhashed to avoid closed
1804          * socket sitting in hash tables.
1805          */
1806         sk->sk_state = state;
1807
1808 #ifdef STATE_TRACE
1809         SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1810 #endif
1811 }
1812 EXPORT_SYMBOL_GPL(tcp_set_state);
1813
1814 /*
1815  *      State processing on a close. This implements the state shift for
1816  *      sending our FIN frame. Note that we only send a FIN for some
1817  *      states. A shutdown() may have already sent the FIN, or we may be
1818  *      closed.
1819  */
1820
1821 static const unsigned char new_state[16] = {
1822   /* current state:        new state:      action:      */
1823   /* (Invalid)          */ TCP_CLOSE,
1824   /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1825   /* TCP_SYN_SENT       */ TCP_CLOSE,
1826   /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1827   /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1828   /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1829   /* TCP_TIME_WAIT      */ TCP_CLOSE,
1830   /* TCP_CLOSE          */ TCP_CLOSE,
1831   /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1832   /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1833   /* TCP_LISTEN         */ TCP_CLOSE,
1834   /* TCP_CLOSING        */ TCP_CLOSING,
1835 };
1836
1837 static int tcp_close_state(struct sock *sk)
1838 {
1839         int next = (int)new_state[sk->sk_state];
1840         int ns = next & TCP_STATE_MASK;
1841
1842         tcp_set_state(sk, ns);
1843
1844         return next & TCP_ACTION_FIN;
1845 }
1846
1847 /*
1848  *      Shutdown the sending side of a connection. Much like close except
1849  *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1850  */
1851
1852 void tcp_shutdown(struct sock *sk, int how)
1853 {
1854         /*      We need to grab some memory, and put together a FIN,
1855          *      and then put it into the queue to be sent.
1856          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1857          */
1858         if (!(how & SEND_SHUTDOWN))
1859                 return;
1860
1861         /* If we've already sent a FIN, or it's a closed state, skip this. */
1862         if ((1 << sk->sk_state) &
1863             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1864              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1865                 /* Clear out any half completed packets.  FIN if needed. */
1866                 if (tcp_close_state(sk))
1867                         tcp_send_fin(sk);
1868         }
1869 }
1870
1871 void tcp_close(struct sock *sk, long timeout)
1872 {
1873         struct sk_buff *skb;
1874         int data_was_unread = 0;
1875         int state;
1876
1877         lock_sock(sk);
1878         sk->sk_shutdown = SHUTDOWN_MASK;
1879
1880         if (sk->sk_state == TCP_LISTEN) {
1881                 tcp_set_state(sk, TCP_CLOSE);
1882
1883                 /* Special case. */
1884                 inet_csk_listen_stop(sk);
1885
1886                 goto adjudge_to_death;
1887         }
1888
1889         /*  We need to flush the recv. buffs.  We do this only on the
1890          *  descriptor close, not protocol-sourced closes, because the
1891          *  reader process may not have drained the data yet!
1892          */
1893         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1894                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1895                           tcp_hdr(skb)->fin;
1896                 data_was_unread += len;
1897                 __kfree_skb(skb);
1898         }
1899
1900         sk_mem_reclaim(sk);
1901
1902         /* As outlined in RFC 2525, section 2.17, we send a RST here because
1903          * data was lost. To witness the awful effects of the old behavior of
1904          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
1905          * GET in an FTP client, suspend the process, wait for the client to
1906          * advertise a zero window, then kill -9 the FTP client, wheee...
1907          * Note: timeout is always zero in such a case.
1908          */
1909         if (data_was_unread) {
1910                 /* Unread data was tossed, zap the connection. */
1911                 NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
1912                 tcp_set_state(sk, TCP_CLOSE);
1913                 tcp_send_active_reset(sk, sk->sk_allocation);
1914         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1915                 /* Check zero linger _after_ checking for unread data. */
1916                 sk->sk_prot->disconnect(sk, 0);
1917                 NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
1918         } else if (tcp_close_state(sk)) {
1919                 /* We FIN if the application ate all the data before
1920                  * zapping the connection.
1921                  */
1922
1923                 /* RED-PEN. Formally speaking, we have broken TCP state
1924                  * machine. State transitions:
1925                  *
1926                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1927                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1928                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1929                  *
1930                  * are legal only when FIN has been sent (i.e. in window),
1931                  * rather than queued out of window. Purists blame.
1932                  *
1933                  * F.e. "RFC state" is ESTABLISHED,
1934                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1935                  *
1936                  * The visible declinations are that sometimes
1937                  * we enter time-wait state, when it is not required really
1938                  * (harmless), do not send active resets, when they are
1939                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1940                  * they look as CLOSING or LAST_ACK for Linux)
1941                  * Probably, I missed some more holelets.
1942                  *                                              --ANK
1943                  */
1944                 tcp_send_fin(sk);
1945         }
1946
1947         sk_stream_wait_close(sk, timeout);
1948
1949 adjudge_to_death:
1950         state = sk->sk_state;
1951         sock_hold(sk);
1952         sock_orphan(sk);
1953
1954         /* It is the last release_sock in its life. It will remove backlog. */
1955         release_sock(sk);
1956
1957
1958         /* Now socket is owned by kernel and we acquire BH lock
1959            to finish close. No need to check for user refs.
1960          */
1961         local_bh_disable();
1962         bh_lock_sock(sk);
1963         WARN_ON(sock_owned_by_user(sk));
1964
1965         percpu_counter_inc(sk->sk_prot->orphan_count);
1966
1967         /* Have we already been destroyed by a softirq or backlog? */
1968         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1969                 goto out;
1970
1971         /*      This is a (useful) BSD violating of the RFC. There is a
1972          *      problem with TCP as specified in that the other end could
1973          *      keep a socket open forever with no application left this end.
1974          *      We use a 3 minute timeout (about the same as BSD) then kill
1975          *      our end. If they send after that then tough - BUT: long enough
1976          *      that we won't make the old 4*rto = almost no time - whoops
1977          *      reset mistake.
1978          *
1979          *      Nope, it was not mistake. It is really desired behaviour
1980          *      f.e. on http servers, when such sockets are useless, but
1981          *      consume significant resources. Let's do it with special
1982          *      linger2 option.                                 --ANK
1983          */
1984
1985         if (sk->sk_state == TCP_FIN_WAIT2) {
1986                 struct tcp_sock *tp = tcp_sk(sk);
1987                 if (tp->linger2 < 0) {
1988                         tcp_set_state(sk, TCP_CLOSE);
1989                         tcp_send_active_reset(sk, GFP_ATOMIC);
1990                         NET_INC_STATS_BH(sock_net(sk),
1991                                         LINUX_MIB_TCPABORTONLINGER);
1992                 } else {
1993                         const int tmo = tcp_fin_time(sk);
1994
1995                         if (tmo > TCP_TIMEWAIT_LEN) {
1996                                 inet_csk_reset_keepalive_timer(sk,
1997                                                 tmo - TCP_TIMEWAIT_LEN);
1998                         } else {
1999                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2000                                 goto out;
2001                         }
2002                 }
2003         }
2004         if (sk->sk_state != TCP_CLOSE) {
2005                 int orphan_count = percpu_counter_read_positive(
2006                                                 sk->sk_prot->orphan_count);
2007
2008                 sk_mem_reclaim(sk);
2009                 if (tcp_too_many_orphans(sk, orphan_count)) {
2010                         if (net_ratelimit())
2011                                 printk(KERN_INFO "TCP: too many of orphaned "
2012                                        "sockets\n");
2013                         tcp_set_state(sk, TCP_CLOSE);
2014                         tcp_send_active_reset(sk, GFP_ATOMIC);
2015                         NET_INC_STATS_BH(sock_net(sk),
2016                                         LINUX_MIB_TCPABORTONMEMORY);
2017                 }
2018         }
2019
2020         if (sk->sk_state == TCP_CLOSE)
2021                 inet_csk_destroy_sock(sk);
2022         /* Otherwise, socket is reprieved until protocol close. */
2023
2024 out:
2025         bh_unlock_sock(sk);
2026         local_bh_enable();
2027         sock_put(sk);
2028 }
2029
2030 /* These states need RST on ABORT according to RFC793 */
2031
2032 static inline int tcp_need_reset(int state)
2033 {
2034         return (1 << state) &
2035                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2036                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2037 }
2038
2039 int tcp_disconnect(struct sock *sk, int flags)
2040 {
2041         struct inet_sock *inet = inet_sk(sk);
2042         struct inet_connection_sock *icsk = inet_csk(sk);
2043         struct tcp_sock *tp = tcp_sk(sk);
2044         int err = 0;
2045         int old_state = sk->sk_state;
2046
2047         if (old_state != TCP_CLOSE)
2048                 tcp_set_state(sk, TCP_CLOSE);
2049
2050         /* ABORT function of RFC793 */
2051         if (old_state == TCP_LISTEN) {
2052                 inet_csk_listen_stop(sk);
2053         } else if (tcp_need_reset(old_state) ||
2054                    (tp->snd_nxt != tp->write_seq &&
2055                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2056                 /* The last check adjusts for discrepancy of Linux wrt. RFC
2057                  * states
2058                  */
2059                 tcp_send_active_reset(sk, gfp_any());
2060                 sk->sk_err = ECONNRESET;
2061         } else if (old_state == TCP_SYN_SENT)
2062                 sk->sk_err = ECONNRESET;
2063
2064         tcp_clear_xmit_timers(sk);
2065         __skb_queue_purge(&sk->sk_receive_queue);
2066         tcp_write_queue_purge(sk);
2067         __skb_queue_purge(&tp->out_of_order_queue);
2068 #ifdef CONFIG_NET_DMA
2069         __skb_queue_purge(&sk->sk_async_wait_queue);
2070 #endif
2071
2072         inet->inet_dport = 0;
2073
2074         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2075                 inet_reset_saddr(sk);
2076
2077         sk->sk_shutdown = 0;
2078         sock_reset_flag(sk, SOCK_DONE);
2079         tp->srtt = 0;
2080         if ((tp->write_seq += tp->max_window + 2) == 0)
2081                 tp->write_seq = 1;
2082         icsk->icsk_backoff = 0;
2083         tp->snd_cwnd = 2;
2084         icsk->icsk_probes_out = 0;
2085         tp->packets_out = 0;
2086         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2087         tp->snd_cwnd_cnt = 0;
2088         tp->bytes_acked = 0;
2089         tp->window_clamp = 0;
2090         tcp_set_ca_state(sk, TCP_CA_Open);
2091         tcp_clear_retrans(tp);
2092         inet_csk_delack_init(sk);
2093         tcp_init_send_head(sk);
2094         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2095         __sk_dst_reset(sk);
2096
2097         WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
2098
2099         sk->sk_error_report(sk);
2100         return err;
2101 }
2102
2103 /*
2104  *      Socket option code for TCP.
2105  */
2106 static int do_tcp_setsockopt(struct sock *sk, int level,
2107                 int optname, char __user *optval, unsigned int optlen)
2108 {
2109         struct tcp_sock *tp = tcp_sk(sk);
2110         struct inet_connection_sock *icsk = inet_csk(sk);
2111         int val;
2112         int err = 0;
2113
2114         /* These are data/string values, all the others are ints */
2115         switch (optname) {
2116         case TCP_CONGESTION: {
2117                 char name[TCP_CA_NAME_MAX];
2118
2119                 if (optlen < 1)
2120                         return -EINVAL;
2121
2122                 val = strncpy_from_user(name, optval,
2123                                         min_t(long, TCP_CA_NAME_MAX-1, optlen));
2124                 if (val < 0)
2125                         return -EFAULT;
2126                 name[val] = 0;
2127
2128                 lock_sock(sk);
2129                 err = tcp_set_congestion_control(sk, name);
2130                 release_sock(sk);
2131                 return err;
2132         }
2133         case TCP_COOKIE_TRANSACTIONS: {
2134                 struct tcp_cookie_transactions ctd;
2135                 struct tcp_cookie_values *cvp = NULL;
2136
2137                 if (sizeof(ctd) > optlen)
2138                         return -EINVAL;
2139                 if (copy_from_user(&ctd, optval, sizeof(ctd)))
2140                         return -EFAULT;
2141
2142                 if (ctd.tcpct_used > sizeof(ctd.tcpct_value) ||
2143                     ctd.tcpct_s_data_desired > TCP_MSS_DESIRED)
2144                         return -EINVAL;
2145
2146                 if (ctd.tcpct_cookie_desired == 0) {
2147                         /* default to global value */
2148                 } else if ((0x1 & ctd.tcpct_cookie_desired) ||
2149                            ctd.tcpct_cookie_desired > TCP_COOKIE_MAX ||
2150                            ctd.tcpct_cookie_desired < TCP_COOKIE_MIN) {
2151                         return -EINVAL;
2152                 }
2153
2154                 if (TCP_COOKIE_OUT_NEVER & ctd.tcpct_flags) {
2155                         /* Supercedes all other values */
2156                         lock_sock(sk);
2157                         if (tp->cookie_values != NULL) {
2158                                 kref_put(&tp->cookie_values->kref,
2159                                          tcp_cookie_values_release);
2160                                 tp->cookie_values = NULL;
2161                         }
2162                         tp->rx_opt.cookie_in_always = 0; /* false */
2163                         tp->rx_opt.cookie_out_never = 1; /* true */
2164                         release_sock(sk);
2165                         return err;
2166                 }
2167
2168                 /* Allocate ancillary memory before locking.
2169                  */
2170                 if (ctd.tcpct_used > 0 ||
2171                     (tp->cookie_values == NULL &&
2172                      (sysctl_tcp_cookie_size > 0 ||
2173                       ctd.tcpct_cookie_desired > 0 ||
2174                       ctd.tcpct_s_data_desired > 0))) {
2175                         cvp = kzalloc(sizeof(*cvp) + ctd.tcpct_used,
2176                                       GFP_KERNEL);
2177                         if (cvp == NULL)
2178                                 return -ENOMEM;
2179
2180                         kref_init(&cvp->kref);
2181                 }
2182                 lock_sock(sk);
2183                 tp->rx_opt.cookie_in_always =
2184                         (TCP_COOKIE_IN_ALWAYS & ctd.tcpct_flags);
2185                 tp->rx_opt.cookie_out_never = 0; /* false */
2186
2187                 if (tp->cookie_values != NULL) {
2188                         if (cvp != NULL) {
2189                                 /* Changed values are recorded by a changed
2190                                  * pointer, ensuring the cookie will differ,
2191                                  * without separately hashing each value later.
2192                                  */
2193                                 kref_put(&tp->cookie_values->kref,
2194                                          tcp_cookie_values_release);
2195                         } else {
2196                                 cvp = tp->cookie_values;
2197                         }
2198                 }
2199
2200                 if (cvp != NULL) {
2201                         cvp->cookie_desired = ctd.tcpct_cookie_desired;
2202
2203                         if (ctd.tcpct_used > 0) {
2204                                 memcpy(cvp->s_data_payload, ctd.tcpct_value,
2205                                        ctd.tcpct_used);
2206                                 cvp->s_data_desired = ctd.tcpct_used;
2207                                 cvp->s_data_constant = 1; /* true */
2208                         } else {
2209                                 /* No constant payload data. */
2210                                 cvp->s_data_desired = ctd.tcpct_s_data_desired;
2211                                 cvp->s_data_constant = 0; /* false */
2212                         }
2213
2214                         tp->cookie_values = cvp;
2215                 }
2216                 release_sock(sk);
2217                 return err;
2218         }
2219         default:
2220                 /* fallthru */
2221                 break;
2222         }
2223
2224         if (optlen < sizeof(int))
2225                 return -EINVAL;
2226
2227         if (get_user(val, (int __user *)optval))
2228                 return -EFAULT;
2229
2230         lock_sock(sk);
2231
2232         switch (optname) {
2233         case TCP_MAXSEG:
2234                 /* Values greater than interface MTU won't take effect. However
2235                  * at the point when this call is done we typically don't yet
2236                  * know which interface is going to be used */
2237                 if (val < 8 || val > MAX_TCP_WINDOW) {
2238                         err = -EINVAL;
2239                         break;
2240                 }
2241                 tp->rx_opt.user_mss = val;
2242                 break;
2243
2244         case TCP_NODELAY:
2245                 if (val) {
2246                         /* TCP_NODELAY is weaker than TCP_CORK, so that
2247                          * this option on corked socket is remembered, but
2248                          * it is not activated until cork is cleared.
2249                          *
2250                          * However, when TCP_NODELAY is set we make
2251                          * an explicit push, which overrides even TCP_CORK
2252                          * for currently queued segments.
2253                          */
2254                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2255                         tcp_push_pending_frames(sk);
2256                 } else {
2257                         tp->nonagle &= ~TCP_NAGLE_OFF;
2258                 }
2259                 break;
2260
2261         case TCP_THIN_LINEAR_TIMEOUTS:
2262                 if (val < 0 || val > 1)
2263                         err = -EINVAL;
2264                 else
2265                         tp->thin_lto = val;
2266                 break;
2267
2268         case TCP_THIN_DUPACK:
2269                 if (val < 0 || val > 1)
2270                         err = -EINVAL;
2271                 else
2272                         tp->thin_dupack = val;
2273                 break;
2274
2275         case TCP_CORK:
2276                 /* When set indicates to always queue non-full frames.
2277                  * Later the user clears this option and we transmit
2278                  * any pending partial frames in the queue.  This is
2279                  * meant to be used alongside sendfile() to get properly
2280                  * filled frames when the user (for example) must write
2281                  * out headers with a write() call first and then use
2282                  * sendfile to send out the data parts.
2283                  *
2284                  * TCP_CORK can be set together with TCP_NODELAY and it is
2285                  * stronger than TCP_NODELAY.
2286                  */
2287                 if (val) {
2288                         tp->nonagle |= TCP_NAGLE_CORK;
2289                 } else {
2290                         tp->nonagle &= ~TCP_NAGLE_CORK;
2291                         if (tp->nonagle&TCP_NAGLE_OFF)
2292                                 tp->nonagle |= TCP_NAGLE_PUSH;
2293                         tcp_push_pending_frames(sk);
2294                 }
2295                 break;
2296
2297         case TCP_KEEPIDLE:
2298                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
2299                         err = -EINVAL;
2300                 else {
2301                         tp->keepalive_time = val * HZ;
2302                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
2303                             !((1 << sk->sk_state) &
2304                               (TCPF_CLOSE | TCPF_LISTEN))) {
2305                                 u32 elapsed = keepalive_time_elapsed(tp);
2306                                 if (tp->keepalive_time > elapsed)
2307                                         elapsed = tp->keepalive_time - elapsed;
2308                                 else
2309                                         elapsed = 0;
2310                                 inet_csk_reset_keepalive_timer(sk, elapsed);
2311                         }
2312                 }
2313                 break;
2314         case TCP_KEEPINTVL:
2315                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
2316                         err = -EINVAL;
2317                 else
2318                         tp->keepalive_intvl = val * HZ;
2319                 break;
2320         case TCP_KEEPCNT:
2321                 if (val < 1 || val > MAX_TCP_KEEPCNT)
2322                         err = -EINVAL;
2323                 else
2324                         tp->keepalive_probes = val;
2325                 break;
2326         case TCP_SYNCNT:
2327                 if (val < 1 || val > MAX_TCP_SYNCNT)
2328                         err = -EINVAL;
2329                 else
2330                         icsk->icsk_syn_retries = val;
2331                 break;
2332
2333         case TCP_LINGER2:
2334                 if (val < 0)
2335                         tp->linger2 = -1;
2336                 else if (val > sysctl_tcp_fin_timeout / HZ)
2337                         tp->linger2 = 0;
2338                 else
2339                         tp->linger2 = val * HZ;
2340                 break;
2341
2342         case TCP_DEFER_ACCEPT:
2343                 /* Translate value in seconds to number of retransmits */
2344                 icsk->icsk_accept_queue.rskq_defer_accept =
2345                         secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
2346                                         TCP_RTO_MAX / HZ);
2347                 break;
2348
2349         case TCP_WINDOW_CLAMP:
2350                 if (!val) {
2351                         if (sk->sk_state != TCP_CLOSE) {
2352                                 err = -EINVAL;
2353                                 break;
2354                         }
2355                         tp->window_clamp = 0;
2356                 } else
2357                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2358                                                 SOCK_MIN_RCVBUF / 2 : val;
2359                 break;
2360
2361         case TCP_QUICKACK:
2362                 if (!val) {
2363                         icsk->icsk_ack.pingpong = 1;
2364                 } else {
2365                         icsk->icsk_ack.pingpong = 0;
2366                         if ((1 << sk->sk_state) &
2367                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2368                             inet_csk_ack_scheduled(sk)) {
2369                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2370                                 tcp_cleanup_rbuf(sk, 1);
2371                                 if (!(val & 1))
2372                                         icsk->icsk_ack.pingpong = 1;
2373                         }
2374                 }
2375                 break;
2376
2377 #ifdef CONFIG_TCP_MD5SIG
2378         case TCP_MD5SIG:
2379                 /* Read the IP->Key mappings from userspace */
2380                 err = tp->af_specific->md5_parse(sk, optval, optlen);
2381                 break;
2382 #endif
2383
2384         default:
2385                 err = -ENOPROTOOPT;
2386                 break;
2387         }
2388
2389         release_sock(sk);
2390         return err;
2391 }
2392
2393 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2394                    unsigned int optlen)
2395 {
2396         struct inet_connection_sock *icsk = inet_csk(sk);
2397
2398         if (level != SOL_TCP)
2399                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2400                                                      optval, optlen);
2401         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2402 }
2403
2404 #ifdef CONFIG_COMPAT
2405 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2406                           char __user *optval, unsigned int optlen)
2407 {
2408         if (level != SOL_TCP)
2409                 return inet_csk_compat_setsockopt(sk, level, optname,
2410                                                   optval, optlen);
2411         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2412 }
2413
2414 EXPORT_SYMBOL(compat_tcp_setsockopt);
2415 #endif
2416
2417 /* Return information about state of tcp endpoint in API format. */
2418 void tcp_get_info(struct sock *sk, struct tcp_info *info)
2419 {
2420         struct tcp_sock *tp = tcp_sk(sk);
2421         const struct inet_connection_sock *icsk = inet_csk(sk);
2422         u32 now = tcp_time_stamp;
2423
2424         memset(info, 0, sizeof(*info));
2425
2426         info->tcpi_state = sk->sk_state;
2427         info->tcpi_ca_state = icsk->icsk_ca_state;
2428         info->tcpi_retransmits = icsk->icsk_retransmits;
2429         info->tcpi_probes = icsk->icsk_probes_out;
2430         info->tcpi_backoff = icsk->icsk_backoff;
2431
2432         if (tp->rx_opt.tstamp_ok)
2433                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2434         if (tcp_is_sack(tp))
2435                 info->tcpi_options |= TCPI_OPT_SACK;
2436         if (tp->rx_opt.wscale_ok) {
2437                 info->tcpi_options |= TCPI_OPT_WSCALE;
2438                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2439                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2440         }
2441
2442         if (tp->ecn_flags&TCP_ECN_OK)
2443                 info->tcpi_options |= TCPI_OPT_ECN;
2444
2445         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2446         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2447         info->tcpi_snd_mss = tp->mss_cache;
2448         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2449
2450         if (sk->sk_state == TCP_LISTEN) {
2451                 info->tcpi_unacked = sk->sk_ack_backlog;
2452                 info->tcpi_sacked = sk->sk_max_ack_backlog;
2453         } else {
2454                 info->tcpi_unacked = tp->packets_out;
2455                 info->tcpi_sacked = tp->sacked_out;
2456         }
2457         info->tcpi_lost = tp->lost_out;
2458         info->tcpi_retrans = tp->retrans_out;
2459         info->tcpi_fackets = tp->fackets_out;
2460
2461         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2462         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2463         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2464
2465         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2466         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2467         info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2468         info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2469         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2470         info->tcpi_snd_cwnd = tp->snd_cwnd;
2471         info->tcpi_advmss = tp->advmss;
2472         info->tcpi_reordering = tp->reordering;
2473
2474         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2475         info->tcpi_rcv_space = tp->rcvq_space.space;
2476
2477         info->tcpi_total_retrans = tp->total_retrans;
2478 }
2479
2480 EXPORT_SYMBOL_GPL(tcp_get_info);
2481
2482 static int do_tcp_getsockopt(struct sock *sk, int level,
2483                 int optname, char __user *optval, int __user *optlen)
2484 {
2485         struct inet_connection_sock *icsk = inet_csk(sk);
2486         struct tcp_sock *tp = tcp_sk(sk);
2487         int val, len;
2488
2489         if (get_user(len, optlen))
2490                 return -EFAULT;
2491
2492         len = min_t(unsigned int, len, sizeof(int));
2493
2494         if (len < 0)
2495                 return -EINVAL;
2496
2497         switch (optname) {
2498         case TCP_MAXSEG:
2499                 val = tp->mss_cache;
2500                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2501                         val = tp->rx_opt.user_mss;
2502                 break;
2503         case TCP_NODELAY:
2504                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2505                 break;
2506         case TCP_CORK:
2507                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2508                 break;
2509         case TCP_KEEPIDLE:
2510                 val = keepalive_time_when(tp) / HZ;
2511                 break;
2512         case TCP_KEEPINTVL:
2513                 val = keepalive_intvl_when(tp) / HZ;
2514                 break;
2515         case TCP_KEEPCNT:
2516                 val = keepalive_probes(tp);
2517                 break;
2518         case TCP_SYNCNT:
2519                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2520                 break;
2521         case TCP_LINGER2:
2522                 val = tp->linger2;
2523                 if (val >= 0)
2524                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2525                 break;
2526         case TCP_DEFER_ACCEPT:
2527                 val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
2528                                       TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
2529                 break;
2530         case TCP_WINDOW_CLAMP:
2531                 val = tp->window_clamp;
2532                 break;
2533         case TCP_INFO: {
2534                 struct tcp_info info;
2535
2536                 if (get_user(len, optlen))
2537                         return -EFAULT;
2538
2539                 tcp_get_info(sk, &info);
2540
2541                 len = min_t(unsigned int, len, sizeof(info));
2542                 if (put_user(len, optlen))
2543                         return -EFAULT;
2544                 if (copy_to_user(optval, &info, len))
2545                         return -EFAULT;
2546                 return 0;
2547         }
2548         case TCP_QUICKACK:
2549                 val = !icsk->icsk_ack.pingpong;
2550                 break;
2551
2552         case TCP_CONGESTION:
2553                 if (get_user(len, optlen))
2554                         return -EFAULT;
2555                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2556                 if (put_user(len, optlen))
2557                         return -EFAULT;
2558                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2559                         return -EFAULT;
2560                 return 0;
2561
2562         case TCP_COOKIE_TRANSACTIONS: {
2563                 struct tcp_cookie_transactions ctd;
2564                 struct tcp_cookie_values *cvp = tp->cookie_values;
2565
2566                 if (get_user(len, optlen))
2567                         return -EFAULT;
2568                 if (len < sizeof(ctd))
2569                         return -EINVAL;
2570
2571                 memset(&ctd, 0, sizeof(ctd));
2572                 ctd.tcpct_flags = (tp->rx_opt.cookie_in_always ?
2573                                    TCP_COOKIE_IN_ALWAYS : 0)
2574                                 | (tp->rx_opt.cookie_out_never ?
2575                                    TCP_COOKIE_OUT_NEVER : 0);
2576
2577                 if (cvp != NULL) {
2578                         ctd.tcpct_flags |= (cvp->s_data_in ?
2579                                             TCP_S_DATA_IN : 0)
2580                                          | (cvp->s_data_out ?
2581                                             TCP_S_DATA_OUT : 0);
2582
2583                         ctd.tcpct_cookie_desired = cvp->cookie_desired;
2584                         ctd.tcpct_s_data_desired = cvp->s_data_desired;
2585
2586                         memcpy(&ctd.tcpct_value[0], &cvp->cookie_pair[0],
2587                                cvp->cookie_pair_size);
2588                         ctd.tcpct_used = cvp->cookie_pair_size;
2589                 }
2590
2591                 if (put_user(sizeof(ctd), optlen))
2592                         return -EFAULT;
2593                 if (copy_to_user(optval, &ctd, sizeof(ctd)))
2594                         return -EFAULT;
2595                 return 0;
2596         }
2597         default:
2598                 return -ENOPROTOOPT;
2599         }
2600
2601         if (put_user(len, optlen))
2602                 return -EFAULT;
2603         if (copy_to_user(optval, &val, len))
2604                 return -EFAULT;
2605         return 0;
2606 }
2607
2608 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2609                    int __user *optlen)
2610 {
2611         struct inet_connection_sock *icsk = inet_csk(sk);
2612
2613         if (level != SOL_TCP)
2614                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2615                                                      optval, optlen);
2616         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2617 }
2618
2619 #ifdef CONFIG_COMPAT
2620 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2621                           char __user *optval, int __user *optlen)
2622 {
2623         if (level != SOL_TCP)
2624                 return inet_csk_compat_getsockopt(sk, level, optname,
2625                                                   optval, optlen);
2626         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2627 }
2628
2629 EXPORT_SYMBOL(compat_tcp_getsockopt);
2630 #endif
2631
2632 struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2633 {
2634         struct sk_buff *segs = ERR_PTR(-EINVAL);
2635         struct tcphdr *th;
2636         unsigned thlen;
2637         unsigned int seq;
2638         __be32 delta;
2639         unsigned int oldlen;
2640         unsigned int mss;
2641
2642         if (!pskb_may_pull(skb, sizeof(*th)))
2643                 goto out;
2644
2645         th = tcp_hdr(skb);
2646         thlen = th->doff * 4;
2647         if (thlen < sizeof(*th))
2648                 goto out;
2649
2650         if (!pskb_may_pull(skb, thlen))
2651                 goto out;
2652
2653         oldlen = (u16)~skb->len;
2654         __skb_pull(skb, thlen);
2655
2656         mss = skb_shinfo(skb)->gso_size;
2657         if (unlikely(skb->len <= mss))
2658                 goto out;
2659
2660         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2661                 /* Packet is from an untrusted source, reset gso_segs. */
2662                 int type = skb_shinfo(skb)->gso_type;
2663
2664                 if (unlikely(type &
2665                              ~(SKB_GSO_TCPV4 |
2666                                SKB_GSO_DODGY |
2667                                SKB_GSO_TCP_ECN |
2668                                SKB_GSO_TCPV6 |
2669                                0) ||
2670                              !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2671                         goto out;
2672
2673                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
2674
2675                 segs = NULL;
2676                 goto out;
2677         }
2678
2679         segs = skb_segment(skb, features);
2680         if (IS_ERR(segs))
2681                 goto out;
2682
2683         delta = htonl(oldlen + (thlen + mss));
2684
2685         skb = segs;
2686         th = tcp_hdr(skb);
2687         seq = ntohl(th->seq);
2688
2689         do {
2690                 th->fin = th->psh = 0;
2691
2692                 th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2693                                        (__force u32)delta));
2694                 if (skb->ip_summed != CHECKSUM_PARTIAL)
2695                         th->check =
2696                              csum_fold(csum_partial(skb_transport_header(skb),
2697                                                     thlen, skb->csum));
2698
2699                 seq += mss;
2700                 skb = skb->next;
2701                 th = tcp_hdr(skb);
2702
2703                 th->seq = htonl(seq);
2704                 th->cwr = 0;
2705         } while (skb->next);
2706
2707         delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2708                       skb->data_len);
2709         th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2710                                 (__force u32)delta));
2711         if (skb->ip_summed != CHECKSUM_PARTIAL)
2712                 th->check = csum_fold(csum_partial(skb_transport_header(skb),
2713                                                    thlen, skb->csum));
2714
2715 out:
2716         return segs;
2717 }
2718 EXPORT_SYMBOL(tcp_tso_segment);
2719
2720 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2721 {
2722         struct sk_buff **pp = NULL;
2723         struct sk_buff *p;
2724         struct tcphdr *th;
2725         struct tcphdr *th2;
2726         unsigned int len;
2727         unsigned int thlen;
2728         __be32 flags;
2729         unsigned int mss = 1;
2730         unsigned int hlen;
2731         unsigned int off;
2732         int flush = 1;
2733         int i;
2734
2735         off = skb_gro_offset(skb);
2736         hlen = off + sizeof(*th);
2737         th = skb_gro_header_fast(skb, off);
2738         if (skb_gro_header_hard(skb, hlen)) {
2739                 th = skb_gro_header_slow(skb, hlen, off);
2740                 if (unlikely(!th))
2741                         goto out;
2742         }
2743
2744         thlen = th->doff * 4;
2745         if (thlen < sizeof(*th))
2746                 goto out;
2747
2748         hlen = off + thlen;
2749         if (skb_gro_header_hard(skb, hlen)) {
2750                 th = skb_gro_header_slow(skb, hlen, off);
2751                 if (unlikely(!th))
2752                         goto out;
2753         }
2754
2755         skb_gro_pull(skb, thlen);
2756
2757         len = skb_gro_len(skb);
2758         flags = tcp_flag_word(th);
2759
2760         for (; (p = *head); head = &p->next) {
2761                 if (!NAPI_GRO_CB(p)->same_flow)
2762                         continue;
2763
2764                 th2 = tcp_hdr(p);
2765
2766                 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
2767                         NAPI_GRO_CB(p)->same_flow = 0;
2768                         continue;
2769                 }
2770
2771                 goto found;
2772         }
2773
2774         goto out_check_final;
2775
2776 found:
2777         flush = NAPI_GRO_CB(p)->flush;
2778         flush |= (__force int)(flags & TCP_FLAG_CWR);
2779         flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
2780                   ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
2781         flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
2782         for (i = sizeof(*th); i < thlen; i += 4)
2783                 flush |= *(u32 *)((u8 *)th + i) ^
2784                          *(u32 *)((u8 *)th2 + i);
2785
2786         mss = skb_shinfo(p)->gso_size;
2787
2788         flush |= (len - 1) >= mss;
2789         flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
2790
2791         if (flush || skb_gro_receive(head, skb)) {
2792                 mss = 1;
2793                 goto out_check_final;
2794         }
2795
2796         p = *head;
2797         th2 = tcp_hdr(p);
2798         tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
2799
2800 out_check_final:
2801         flush = len < mss;
2802         flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
2803                                         TCP_FLAG_RST | TCP_FLAG_SYN |
2804                                         TCP_FLAG_FIN));
2805
2806         if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
2807                 pp = head;
2808
2809 out:
2810         NAPI_GRO_CB(skb)->flush |= flush;
2811
2812         return pp;
2813 }
2814 EXPORT_SYMBOL(tcp_gro_receive);
2815
2816 int tcp_gro_complete(struct sk_buff *skb)
2817 {
2818         struct tcphdr *th = tcp_hdr(skb);
2819
2820         skb->csum_start = skb_transport_header(skb) - skb->head;
2821         skb->csum_offset = offsetof(struct tcphdr, check);
2822         skb->ip_summed = CHECKSUM_PARTIAL;
2823
2824         skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
2825
2826         if (th->cwr)
2827                 skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
2828
2829         return 0;
2830 }
2831 EXPORT_SYMBOL(tcp_gro_complete);
2832
2833 #ifdef CONFIG_TCP_MD5SIG
2834 static unsigned long tcp_md5sig_users;
2835 static struct tcp_md5sig_pool * __percpu *tcp_md5sig_pool;
2836 static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
2837
2838 static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool * __percpu *pool)
2839 {
2840         int cpu;
2841         for_each_possible_cpu(cpu) {
2842                 struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu);
2843                 if (p) {
2844                         if (p->md5_desc.tfm)
2845                                 crypto_free_hash(p->md5_desc.tfm);
2846                         kfree(p);
2847                 }
2848         }
2849         free_percpu(pool);
2850 }
2851
2852 void tcp_free_md5sig_pool(void)
2853 {
2854         struct tcp_md5sig_pool * __percpu *pool = NULL;
2855
2856         spin_lock_bh(&tcp_md5sig_pool_lock);
2857         if (--tcp_md5sig_users == 0) {
2858                 pool = tcp_md5sig_pool;
2859                 tcp_md5sig_pool = NULL;
2860         }
2861         spin_unlock_bh(&tcp_md5sig_pool_lock);
2862         if (pool)
2863                 __tcp_free_md5sig_pool(pool);
2864 }
2865
2866 EXPORT_SYMBOL(tcp_free_md5sig_pool);
2867
2868 static struct tcp_md5sig_pool * __percpu *
2869 __tcp_alloc_md5sig_pool(struct sock *sk)
2870 {
2871         int cpu;
2872         struct tcp_md5sig_pool * __percpu *pool;
2873
2874         pool = alloc_percpu(struct tcp_md5sig_pool *);
2875         if (!pool)
2876                 return NULL;
2877
2878         for_each_possible_cpu(cpu) {
2879                 struct tcp_md5sig_pool *p;
2880                 struct crypto_hash *hash;
2881
2882                 p = kzalloc(sizeof(*p), sk->sk_allocation);
2883                 if (!p)
2884                         goto out_free;
2885                 *per_cpu_ptr(pool, cpu) = p;
2886
2887                 hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2888                 if (!hash || IS_ERR(hash))
2889                         goto out_free;
2890
2891                 p->md5_desc.tfm = hash;
2892         }
2893         return pool;
2894 out_free:
2895         __tcp_free_md5sig_pool(pool);
2896         return NULL;
2897 }
2898
2899 struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *sk)
2900 {
2901         struct tcp_md5sig_pool * __percpu *pool;
2902         int alloc = 0;
2903
2904 retry:
2905         spin_lock_bh(&tcp_md5sig_pool_lock);
2906         pool = tcp_md5sig_pool;
2907         if (tcp_md5sig_users++ == 0) {
2908                 alloc = 1;
2909                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2910         } else if (!pool) {
2911                 tcp_md5sig_users--;
2912                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2913                 cpu_relax();
2914                 goto retry;
2915         } else
2916                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2917
2918         if (alloc) {
2919                 /* we cannot hold spinlock here because this may sleep. */
2920                 struct tcp_md5sig_pool * __percpu *p;
2921
2922                 p = __tcp_alloc_md5sig_pool(sk);
2923                 spin_lock_bh(&tcp_md5sig_pool_lock);
2924                 if (!p) {
2925                         tcp_md5sig_users--;
2926                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2927                         return NULL;
2928                 }
2929                 pool = tcp_md5sig_pool;
2930                 if (pool) {
2931                         /* oops, it has already been assigned. */
2932                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2933                         __tcp_free_md5sig_pool(p);
2934                 } else {
2935                         tcp_md5sig_pool = pool = p;
2936                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2937                 }
2938         }
2939         return pool;
2940 }
2941
2942 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2943
2944
2945 /**
2946  *      tcp_get_md5sig_pool - get md5sig_pool for this user
2947  *
2948  *      We use percpu structure, so if we succeed, we exit with preemption
2949  *      and BH disabled, to make sure another thread or softirq handling
2950  *      wont try to get same context.
2951  */
2952 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
2953 {
2954         struct tcp_md5sig_pool * __percpu *p;
2955
2956         local_bh_disable();
2957
2958         spin_lock(&tcp_md5sig_pool_lock);
2959         p = tcp_md5sig_pool;
2960         if (p)
2961                 tcp_md5sig_users++;
2962         spin_unlock(&tcp_md5sig_pool_lock);
2963
2964         if (p)
2965                 return *per_cpu_ptr(p, smp_processor_id());
2966
2967         local_bh_enable();
2968         return NULL;
2969 }
2970 EXPORT_SYMBOL(tcp_get_md5sig_pool);
2971
2972 void tcp_put_md5sig_pool(void)
2973 {
2974         local_bh_enable();
2975         tcp_free_md5sig_pool();
2976 }
2977 EXPORT_SYMBOL(tcp_put_md5sig_pool);
2978
2979 int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
2980                         struct tcphdr *th)
2981 {
2982         struct scatterlist sg;
2983         int err;
2984
2985         __sum16 old_checksum = th->check;
2986         th->check = 0;
2987         /* options aren't included in the hash */
2988         sg_init_one(&sg, th, sizeof(struct tcphdr));
2989         err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(struct tcphdr));
2990         th->check = old_checksum;
2991         return err;
2992 }
2993
2994 EXPORT_SYMBOL(tcp_md5_hash_header);
2995
2996 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
2997                           struct sk_buff *skb, unsigned header_len)
2998 {
2999         struct scatterlist sg;
3000         const struct tcphdr *tp = tcp_hdr(skb);
3001         struct hash_desc *desc = &hp->md5_desc;
3002         unsigned i;
3003         const unsigned head_data_len = skb_headlen(skb) > header_len ?
3004                                        skb_headlen(skb) - header_len : 0;
3005         const struct skb_shared_info *shi = skb_shinfo(skb);
3006
3007         sg_init_table(&sg, 1);
3008
3009         sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
3010         if (crypto_hash_update(desc, &sg, head_data_len))
3011                 return 1;
3012
3013         for (i = 0; i < shi->nr_frags; ++i) {
3014                 const struct skb_frag_struct *f = &shi->frags[i];
3015                 sg_set_page(&sg, f->page, f->size, f->page_offset);
3016                 if (crypto_hash_update(desc, &sg, f->size))
3017                         return 1;
3018         }
3019
3020         return 0;
3021 }
3022
3023 EXPORT_SYMBOL(tcp_md5_hash_skb_data);
3024
3025 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, struct tcp_md5sig_key *key)
3026 {
3027         struct scatterlist sg;
3028
3029         sg_init_one(&sg, key->key, key->keylen);
3030         return crypto_hash_update(&hp->md5_desc, &sg, key->keylen);
3031 }
3032
3033 EXPORT_SYMBOL(tcp_md5_hash_key);
3034
3035 #endif
3036
3037 /**
3038  * Each Responder maintains up to two secret values concurrently for
3039  * efficient secret rollover.  Each secret value has 4 states:
3040  *
3041  * Generating.  (tcp_secret_generating != tcp_secret_primary)
3042  *    Generates new Responder-Cookies, but not yet used for primary
3043  *    verification.  This is a short-term state, typically lasting only
3044  *    one round trip time (RTT).
3045  *
3046  * Primary.  (tcp_secret_generating == tcp_secret_primary)
3047  *    Used both for generation and primary verification.
3048  *
3049  * Retiring.  (tcp_secret_retiring != tcp_secret_secondary)
3050  *    Used for verification, until the first failure that can be
3051  *    verified by the newer Generating secret.  At that time, this
3052  *    cookie's state is changed to Secondary, and the Generating
3053  *    cookie's state is changed to Primary.  This is a short-term state,
3054  *    typically lasting only one round trip time (RTT).
3055  *
3056  * Secondary.  (tcp_secret_retiring == tcp_secret_secondary)
3057  *    Used for secondary verification, after primary verification