Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4

Linux/net/ipv4/tcp.c

  1 /*
  2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  3  *              operating system.  INET is implemented using the  BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  *              Implementation of the Transmission Control Protocol(TCP).
  7  *
  8  * Authors:     Ross Biro
  9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 10  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
 11  *              Corey Minyard <wf-rch!minyard@relay.EU.net>
 12  *              Florian La Roche, <flla@stud.uni-sb.de>
 13  *              Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
 14  *              Linus Torvalds, <torvalds@cs.helsinki.fi>
 15  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
 16  *              Matthew Dillon, <dillon@apollo.west.oic.com>
 17  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 18  *              Jorge Cwik, <jorge@laser.satlink.net>
 19  *
 20  * Fixes:
 21  *              Alan Cox        :       Numerous verify_area() calls
 22  *              Alan Cox        :       Set the ACK bit on a reset
 23  *              Alan Cox        :       Stopped it crashing if it closed while
 24  *                                      sk->inuse=1 and was trying to connect
 25  *                                      (tcp_err()).
 26  *              Alan Cox        :       All icmp error handling was broken
 27  *                                      pointers passed where wrong and the
 28  *                                      socket was looked up backwards. Nobody
 29  *                                      tested any icmp error code obviously.
 30  *              Alan Cox        :       tcp_err() now handled properly. It
 31  *                                      wakes people on errors. poll
 32  *                                      behaves and the icmp error race
 33  *                                      has gone by moving it into sock.c
 34  *              Alan Cox        :       tcp_send_reset() fixed to work for
 35  *                                      everything not just packets for
 36  *                                      unknown sockets.
 37  *              Alan Cox        :       tcp option processing.
 38  *              Alan Cox        :       Reset tweaked (still not 100%) [Had
 39  *                                      syn rule wrong]
 40  *              Herp Rosmanith  :       More reset fixes
 41  *              Alan Cox        :       No longer acks invalid rst frames.
 42  *                                      Acking any kind of RST is right out.
 43  *              Alan Cox        :       Sets an ignore me flag on an rst
 44  *                                      receive otherwise odd bits of prattle
 45  *                                      escape still
 46  *              Alan Cox        :       Fixed another acking RST frame bug.
 47  *                                      Should stop LAN workplace lockups.
 48  *              Alan Cox        :       Some tidyups using the new skb list
 49  *                                      facilities
 50  *              Alan Cox        :       sk->keepopen now seems to work
 51  *              Alan Cox        :       Pulls options out correctly on accepts
 52  *              Alan Cox        :       Fixed assorted sk->rqueue->next errors
 53  *              Alan Cox        :       PSH doesn't end a TCP read. Switched a
 54  *                                      bit to skb ops.
 55  *              Alan Cox        :       Tidied tcp_data to avoid a potential
 56  *                                      nasty.
 57  *              Alan Cox        :       Added some better commenting, as the
 58  *                                      tcp is hard to follow
 59  *              Alan Cox        :       Removed incorrect check for 20 * psh
 60  *      Michael O'Reilly        :       ack < copied bug fix.
 61  *      Johannes Stille         :       Misc tcp fixes (not all in yet).
 62  *              Alan Cox        :       FIN with no memory -> CRASH
 63  *              Alan Cox        :       Added socket option proto entries.
 64  *                                      Also added awareness of them to accept.
 65  *              Alan Cox        :       Added TCP options (SOL_TCP)
 66  *              Alan Cox        :       Switched wakeup calls to callbacks,
 67  *                                      so the kernel can layer network
 68  *                                      sockets.
 69  *              Alan Cox        :       Use ip_tos/ip_ttl settings.
 70  *              Alan Cox        :       Handle FIN (more) properly (we hope).
 71  *              Alan Cox        :       RST frames sent on unsynchronised
 72  *                                      state ack error.
 73  *              Alan Cox        :       Put in missing check for SYN bit.
 74  *              Alan Cox        :       Added tcp_select_window() aka NET2E
 75  *                                      window non shrink trick.
 76  *              Alan Cox        :       Added a couple of small NET2E timer
 77  *                                      fixes
 78  *              Charles Hedrick :       TCP fixes
 79  *              Toomas Tamm     :       TCP window fixes
 80  *              Alan Cox        :       Small URG fix to rlogin ^C ack fight
 81  *              Charles Hedrick :       Rewrote most of it to actually work
 82  *              Linus           :       Rewrote tcp_read() and URG handling
 83  *                                      completely
 84  *              Gerhard Koerting:       Fixed some missing timer handling
 85  *              Matthew Dillon  :       Reworked TCP machine states as per RFC
 86  *              Gerhard Koerting:       PC/TCP workarounds
 87  *              Adam Caldwell   :       Assorted timer/timing errors
 88  *              Matthew Dillon  :       Fixed another RST bug
 89  *              Alan Cox        :       Move to kernel side addressing changes.
 90  *              Alan Cox        :       Beginning work on TCP fastpathing
 91  *                                      (not yet usable)
 92  *              Arnt Gulbrandsen:       Turbocharged tcp_check() routine.
 93  *              Alan Cox        :       TCP fast path debugging
 94  *              Alan Cox        :       Window clamping
 95  *              Michael Riepe   :       Bug in tcp_check()
 96  *              Matt Dillon     :       More TCP improvements and RST bug fixes
 97  *              Matt Dillon     :       Yet more small nasties remove from the
 98  *                                      TCP code (Be very nice to this man if
 99  *                                      tcp finally works 100%) 8)
100  *              Alan Cox        :       BSD accept semantics.
101  *              Alan Cox        :       Reset on closedown bug.
102  *      Peter De Schrijver      :       ENOTCONN check missing in tcp_sendto().
103  *              Michael Pall    :       Handle poll() after URG properly in
104  *                                      all cases.
105  *              Michael Pall    :       Undo the last fix in tcp_read_urg()
106  *                                      (multi URG PUSH broke rlogin).
107  *              Michael Pall    :       Fix the multi URG PUSH problem in
108  *                                      tcp_readable(), poll() after URG
109  *                                      works now.
110  *              Michael Pall    :       recv(...,MSG_OOB) never blocks in the
111  *                                      BSD api.
112  *              Alan Cox        :       Changed the semantics of sk->socket to
113  *                                      fix a race and a signal problem with
114  *                                      accept() and async I/O.
115  *              Alan Cox        :       Relaxed the rules on tcp_sendto().
116  *              Yury Shevchuk   :       Really fixed accept() blocking problem.
117  *              Craig I. Hagan  :       Allow for BSD compatible TIME_WAIT for
118  *                                      clients/servers which listen in on
119  *                                      fixed ports.
120  *              Alan Cox        :       Cleaned the above up and shrank it to
121  *                                      a sensible code size.
122  *              Alan Cox        :       Self connect lockup fix.
123  *              Alan Cox        :       No connect to multicast.
124  *              Ross Biro       :       Close unaccepted children on master
125  *                                      socket close.
126  *              Alan Cox        :       Reset tracing code.
127  *              Alan Cox        :       Spurious resets on shutdown.
128  *              Alan Cox        :       Giant 15 minute/60 second timer error
129  *              Alan Cox        :       Small whoops in polling before an
130  *                                      accept.
131  *              Alan Cox        :       Kept the state trace facility since
132  *                                      it's handy for debugging.
133  *              Alan Cox        :       More reset handler fixes.
134  *              Alan Cox        :       Started rewriting the code based on
135  *                                      the RFC's for other useful protocol
136  *                                      references see: Comer, KA9Q NOS, and
137  *                                      for a reference on the difference
138  *                                      between specifications and how BSD
139  *                                      works see the 4.4lite source.
140  *              A.N.Kuznetsov   :       Don't time wait on completion of tidy
141  *                                      close.
142  *              Linus Torvalds  :       Fin/Shutdown & copied_seq changes.
143  *              Linus Torvalds  :       Fixed BSD port reuse to work first syn
144  *              Alan Cox        :       Reimplemented timers as per the RFC
145  *                                      and using multiple timers for sanity.
146  *              Alan Cox        :       Small bug fixes, and a lot of new
147  *                                      comments.
148  *              Alan Cox        :       Fixed dual reader crash by locking
149  *                                      the buffers (much like datagram.c)
150  *              Alan Cox        :       Fixed stuck sockets in probe. A probe
151  *                                      now gets fed up of retrying without
152  *                                      (even a no space) answer.
153  *              Alan Cox        :       Extracted closing code better
154  *              Alan Cox        :       Fixed the closing state machine to
155  *                                      resemble the RFC.
156  *              Alan Cox        :       More 'per spec' fixes.
157  *              Jorge Cwik      :       Even faster checksumming.
158  *              Alan Cox        :       tcp_data() doesn't ack illegal PSH
159  *                                      only frames. At least one pc tcp stack
160  *                                      generates them.
161  *              Alan Cox        :       Cache last socket.
162  *              Alan Cox        :       Per route irtt.
163  *              Matt Day        :       poll()->select() match BSD precisely on error
164  *              Alan Cox        :       New buffers
165  *              Marc Tamsky     :       Various sk->prot->retransmits and
166  *                                      sk->retransmits misupdating fixed.
167  *                                      Fixed tcp_write_timeout: stuck close,
168  *                                      and TCP syn retries gets used now.
169  *              Mark Yarvis     :       In tcp_read_wakeup(), don't send an
170  *                                      ack if state is TCP_CLOSED.
171  *              Alan Cox        :       Look up device on a retransmit - routes may
172  *                                      change. Doesn't yet cope with MSS shrink right
173  *                                      but it's a start!
174  *              Marc Tamsky     :       Closing in closing fixes.
175  *              Mike Shaver     :       RFC1122 verifications.
176  *              Alan Cox        :       rcv_saddr errors.
177  *              Alan Cox        :       Block double connect().
178  *              Alan Cox        :       Small hooks for enSKIP.
179  *              Alexey Kuznetsov:       Path MTU discovery.
180  *              Alan Cox        :       Support soft errors.
181  *              Alan Cox        :       Fix MTU discovery pathological case
182  *                                      when the remote claims no mtu!
183  *              Marc Tamsky     :       TCP_CLOSE fix.
184  *              Colin (G3TNE)   :       Send a reset on syn ack replies in
185  *                                      window but wrong (fixes NT lpd problems)
186  *              Pedro Roque     :       Better TCP window handling, delayed ack.
187  *              Joerg Reuter    :       No modification of locked buffers in
188  *                                      tcp_do_retransmit()
189  *              Eric Schenk     :       Changed receiver side silly window
190  *                                      avoidance algorithm to BSD style
191  *                                      algorithm. This doubles throughput
192  *                                      against machines running Solaris,
193  *                                      and seems to result in general
194  *                                      improvement.
195  *      Stefan Magdalinski      :       adjusted tcp_readable() to fix FIONREAD
196  *      Willy Konynenberg       :       Transparent proxying support.
197  *      Mike McLagan            :       Routing by source
198  *              Keith Owens     :       Do proper merging with partial SKB's in
199  *                                      tcp_do_sendmsg to avoid burstiness.
200  *              Eric Schenk     :       Fix fast close down bug with
201  *                                      shutdown() followed by close().
202  *              Andi Kleen      :       Make poll agree with SIGIO
203  *      Salvatore Sanfilippo    :       Support SO_LINGER with linger == 1 and
204  *                                      lingertime == 0 (RFC 793 ABORT Call)
205  *      Hirokazu Takahashi      :       Use copy_from_user() instead of
206  *                                      csum_and_copy_from_user() if possible.
207  *
208  *              This program is free software; you can redistribute it and/or
209  *              modify it under the terms of the GNU General Public License
210  *              as published by the Free Software Foundation; either version
211  *              2 of the License, or(at your option) any later version.
212  *
213  * Description of States:
214  *
215  *      TCP_SYN_SENT            sent a connection request, waiting for ack
216  *
217  *      TCP_SYN_RECV            received a connection request, sent ack,
218  *                              waiting for final ack in three-way handshake.
219  *
220  *      TCP_ESTABLISHED         connection established
221  *
222  *      TCP_FIN_WAIT1           our side has shutdown, waiting to complete
223  *                              transmission of remaining buffered data
224  *
225  *      TCP_FIN_WAIT2           all buffered data sent, waiting for remote
226  *                              to shutdown
227  *
228  *      TCP_CLOSING             both sides have shutdown but we still have
229  *                              data we have to finish sending
230  *
231  *      TCP_TIME_WAIT           timeout to catch resent junk before entering
232  *                              closed, can only be entered from FIN_WAIT2
233  *                              or CLOSING.  Required because the other end
234  *                              may not have gotten our last ACK causing it
235  *                              to retransmit the data packet (which we ignore)
236  *
237  *      TCP_CLOSE_WAIT          remote side has shutdown and is waiting for
238  *                              us to finish writing our data and to shutdown
239  *                              (we have to close() to move on to LAST_ACK)
240  *
241  *      TCP_LAST_ACK            out side has shutdown after remote has
242  *                              shutdown.  There may still be data in our
243  *                              buffer that we have to finish sending
244  *
245  *      TCP_CLOSE               socket is finished
246  */
247 
248 #define pr_fmt(fmt) "TCP: " fmt
249 
250 #include <linux/kernel.h>
251 #include <linux/module.h>
252 #include <linux/types.h>
253 #include <linux/fcntl.h>
254 #include <linux/poll.h>
255 #include <linux/inet_diag.h>
256 #include <linux/init.h>
257 #include <linux/fs.h>
258 #include <linux/skbuff.h>
259 #include <linux/scatterlist.h>
260 #include <linux/splice.h>
261 #include <linux/net.h>
262 #include <linux/socket.h>
263 #include <linux/random.h>
264 #include <linux/bootmem.h>
265 #include <linux/highmem.h>
266 #include <linux/swap.h>
267 #include <linux/cache.h>
268 #include <linux/err.h>
269 #include <linux/crypto.h>
270 #include <linux/time.h>
271 #include <linux/slab.h>
272 
273 #include <net/icmp.h>
274 #include <net/inet_common.h>
275 #include <net/tcp.h>
276 #include <net/xfrm.h>
277 #include <net/ip.h>
278 #include <net/sock.h>
279 
280 #include <asm/uaccess.h>
281 #include <asm/ioctls.h>
282 #include <net/busy_poll.h>
283 
284 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
285 
286 int sysctl_tcp_min_tso_segs __read_mostly = 2;
287 
288 int sysctl_tcp_autocorking __read_mostly = 1;
289 
290 struct percpu_counter tcp_orphan_count;
291 EXPORT_SYMBOL_GPL(tcp_orphan_count);
292 
293 long sysctl_tcp_mem[3] __read_mostly;
294 int sysctl_tcp_wmem[3] __read_mostly;
295 int sysctl_tcp_rmem[3] __read_mostly;
296 
297 EXPORT_SYMBOL(sysctl_tcp_mem);
298 EXPORT_SYMBOL(sysctl_tcp_rmem);
299 EXPORT_SYMBOL(sysctl_tcp_wmem);
300 
301 atomic_long_t tcp_memory_allocated;     /* Current allocated memory. */
302 EXPORT_SYMBOL(tcp_memory_allocated);
303 
304 /*
305  * Current number of TCP sockets.
306  */
307 struct percpu_counter tcp_sockets_allocated;
308 EXPORT_SYMBOL(tcp_sockets_allocated);
309 
310 /*
311  * TCP splice context
312  */
313 struct tcp_splice_state {
314         struct pipe_inode_info *pipe;
315         size_t len;
316         unsigned int flags;
317 };
318 
319 /*
320  * Pressure flag: try to collapse.
321  * Technical note: it is used by multiple contexts non atomically.
322  * All the __sk_mem_schedule() is of this nature: accounting
323  * is strict, actions are advisory and have some latency.
324  */
325 int tcp_memory_pressure __read_mostly;
326 EXPORT_SYMBOL(tcp_memory_pressure);
327 
328 void tcp_enter_memory_pressure(struct sock *sk)
329 {
330         if (!tcp_memory_pressure) {
331                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
332                 tcp_memory_pressure = 1;
333         }
334 }
335 EXPORT_SYMBOL(tcp_enter_memory_pressure);
336 
337 /* Convert seconds to retransmits based on initial and max timeout */
338 static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
339 {
340         u8 res = 0;
341 
342         if (seconds > 0) {
343                 int period = timeout;
344 
345                 res = 1;
346                 while (seconds > period && res < 255) {
347                         res++;
348                         timeout <<= 1;
349                         if (timeout > rto_max)
350                                 timeout = rto_max;
351                         period += timeout;
352                 }
353         }
354         return res;
355 }
356 
357 /* Convert retransmits to seconds based on initial and max timeout */
358 static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
359 {
360         int period = 0;
361 
362         if (retrans > 0) {
363                 period = timeout;
364                 while (--retrans) {
365                         timeout <<= 1;
366                         if (timeout > rto_max)
367                                 timeout = rto_max;
368                         period += timeout;
369                 }
370         }
371         return period;
372 }
373 
374 /* Address-family independent initialization for a tcp_sock.
375  *
376  * NOTE: A lot of things set to zero explicitly by call to
377  *       sk_alloc() so need not be done here.
378  */
379 void tcp_init_sock(struct sock *sk)
380 {
381         struct inet_connection_sock *icsk = inet_csk(sk);
382         struct tcp_sock *tp = tcp_sk(sk);
383 
384         __skb_queue_head_init(&tp->out_of_order_queue);
385         tcp_init_xmit_timers(sk);
386         tcp_prequeue_init(tp);
387         INIT_LIST_HEAD(&tp->tsq_node);
388 
389         icsk->icsk_rto = TCP_TIMEOUT_INIT;
390         tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
391         tp->rtt_min[0].rtt = ~0U;
392 
393         /* So many TCP implementations out there (incorrectly) count the
394          * initial SYN frame in their delayed-ACK and congestion control
395          * algorithms that we must have the following bandaid to talk
396          * efficiently to them.  -DaveM
397          */
398         tp->snd_cwnd = TCP_INIT_CWND;
399 
400         /* See draft-stevens-tcpca-spec-01 for discussion of the
401          * initialization of these values.
402          */
403         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
404         tp->snd_cwnd_clamp = ~0;
405         tp->mss_cache = TCP_MSS_DEFAULT;
406         u64_stats_init(&tp->syncp);
407 
408         tp->reordering = sysctl_tcp_reordering;
409         tcp_enable_early_retrans(tp);
410         tcp_assign_congestion_control(sk);
411 
412         tp->tsoffset = 0;
413 
414         sk->sk_state = TCP_CLOSE;
415 
416         sk->sk_write_space = sk_stream_write_space;
417         sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
418 
419         icsk->icsk_sync_mss = tcp_sync_mss;
420 
421         sk->sk_sndbuf = sysctl_tcp_wmem[1];
422         sk->sk_rcvbuf = sysctl_tcp_rmem[1];
423 
424         local_bh_disable();
425         sock_update_memcg(sk);
426         sk_sockets_allocated_inc(sk);
427         local_bh_enable();
428 }
429 EXPORT_SYMBOL(tcp_init_sock);
430 
431 static void tcp_tx_timestamp(struct sock *sk, struct sk_buff *skb)
432 {
433         if (sk->sk_tsflags) {
434                 struct skb_shared_info *shinfo = skb_shinfo(skb);
435 
436                 sock_tx_timestamp(sk, &shinfo->tx_flags);
437                 if (shinfo->tx_flags & SKBTX_ANY_TSTAMP)
438                         shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
439         }
440 }
441 
442 /*
443  *      Wait for a TCP event.
444  *
445  *      Note that we don't need to lock the socket, as the upper poll layers
446  *      take care of normal races (between the test and the event) and we don't
447  *      go look at any of the socket buffers directly.
448  */
449 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
450 {
451         unsigned int mask;
452         struct sock *sk = sock->sk;
453         const struct tcp_sock *tp = tcp_sk(sk);
454         int state;
455 
456         sock_rps_record_flow(sk);
457 
458         sock_poll_wait(file, sk_sleep(sk), wait);
459 
460         state = sk_state_load(sk);
461         if (state == TCP_LISTEN)
462                 return inet_csk_listen_poll(sk);
463 
464         /* Socket is not locked. We are protected from async events
465          * by poll logic and correct handling of state changes
466          * made by other threads is impossible in any case.
467          */
468 
469         mask = 0;
470 
471         /*
472          * POLLHUP is certainly not done right. But poll() doesn't
473          * have a notion of HUP in just one direction, and for a
474          * socket the read side is more interesting.
475          *
476          * Some poll() documentation says that POLLHUP is incompatible
477          * with the POLLOUT/POLLWR flags, so somebody should check this
478          * all. But careful, it tends to be safer to return too many
479          * bits than too few, and you can easily break real applications
480          * if you don't tell them that something has hung up!
481          *
482          * Check-me.
483          *
484          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
485          * our fs/select.c). It means that after we received EOF,
486          * poll always returns immediately, making impossible poll() on write()
487          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
488          * if and only if shutdown has been made in both directions.
489          * Actually, it is interesting to look how Solaris and DUX
490          * solve this dilemma. I would prefer, if POLLHUP were maskable,
491          * then we could set it on SND_SHUTDOWN. BTW examples given
492          * in Stevens' books assume exactly this behaviour, it explains
493          * why POLLHUP is incompatible with POLLOUT.    --ANK
494          *
495          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
496          * blocking on fresh not-connected or disconnected socket. --ANK
497          */
498         if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
499                 mask |= POLLHUP;
500         if (sk->sk_shutdown & RCV_SHUTDOWN)
501                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
502 
503         /* Connected or passive Fast Open socket? */
504         if (state != TCP_SYN_SENT &&
505             (state != TCP_SYN_RECV || tp->fastopen_rsk)) {
506                 int target = sock_rcvlowat(sk, 0, INT_MAX);
507 
508                 if (tp->urg_seq == tp->copied_seq &&
509                     !sock_flag(sk, SOCK_URGINLINE) &&
510                     tp->urg_data)
511                         target++;
512 
513                 if (tp->rcv_nxt - tp->copied_seq >= target)
514                         mask |= POLLIN | POLLRDNORM;
515 
516                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
517                         if (sk_stream_is_writeable(sk)) {
518                                 mask |= POLLOUT | POLLWRNORM;
519                         } else {  /* send SIGIO later */
520                                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
521                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
522 
523                                 /* Race breaker. If space is freed after
524                                  * wspace test but before the flags are set,
525                                  * IO signal will be lost. Memory barrier
526                                  * pairs with the input side.
527                                  */
528                                 smp_mb__after_atomic();
529                                 if (sk_stream_is_writeable(sk))
530                                         mask |= POLLOUT | POLLWRNORM;
531                         }
532                 } else
533                         mask |= POLLOUT | POLLWRNORM;
534 
535                 if (tp->urg_data & TCP_URG_VALID)
536                         mask |= POLLPRI;
537         }
538         /* This barrier is coupled with smp_wmb() in tcp_reset() */
539         smp_rmb();
540         if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
541                 mask |= POLLERR;
542 
543         return mask;
544 }
545 EXPORT_SYMBOL(tcp_poll);
546 
547 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
548 {
549         struct tcp_sock *tp = tcp_sk(sk);
550         int answ;
551         bool slow;
552 
553         switch (cmd) {
554         case SIOCINQ:
555                 if (sk->sk_state == TCP_LISTEN)
556                         return -EINVAL;
557 
558                 slow = lock_sock_fast(sk);
559                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
560                         answ = 0;
561                 else if (sock_flag(sk, SOCK_URGINLINE) ||
562                          !tp->urg_data ||
563                          before(tp->urg_seq, tp->copied_seq) ||
564                          !before(tp->urg_seq, tp->rcv_nxt)) {
565 
566                         answ = tp->rcv_nxt - tp->copied_seq;
567 
568                         /* Subtract 1, if FIN was received */
569                         if (answ && sock_flag(sk, SOCK_DONE))
570                                 answ--;
571                 } else
572                         answ = tp->urg_seq - tp->copied_seq;
573                 unlock_sock_fast(sk, slow);
574                 break;
575         case SIOCATMARK:
576                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
577                 break;
578         case SIOCOUTQ:
579                 if (sk->sk_state == TCP_LISTEN)
580                         return -EINVAL;
581 
582                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
583                         answ = 0;
584                 else
585                         answ = tp->write_seq - tp->snd_una;
586                 break;
587         case SIOCOUTQNSD:
588                 if (sk->sk_state == TCP_LISTEN)
589                         return -EINVAL;
590 
591                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
592                         answ = 0;
593                 else
594                         answ = tp->write_seq - tp->snd_nxt;
595                 break;
596         default:
597                 return -ENOIOCTLCMD;
598         }
599 
600         return put_user(answ, (int __user *)arg);
601 }
602 EXPORT_SYMBOL(tcp_ioctl);
603 
604 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
605 {
606         TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
607         tp->pushed_seq = tp->write_seq;
608 }
609 
610 static inline bool forced_push(const struct tcp_sock *tp)
611 {
612         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
613 }
614 
615 static void skb_entail(struct sock *sk, struct sk_buff *skb)
616 {
617         struct tcp_sock *tp = tcp_sk(sk);
618         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
619 
620         skb->csum    = 0;
621         tcb->seq     = tcb->end_seq = tp->write_seq;
622         tcb->tcp_flags = TCPHDR_ACK;
623         tcb->sacked  = 0;
624         __skb_header_release(skb);
625         tcp_add_write_queue_tail(sk, skb);
626         sk->sk_wmem_queued += skb->truesize;
627         sk_mem_charge(sk, skb->truesize);
628         if (tp->nonagle & TCP_NAGLE_PUSH)
629                 tp->nonagle &= ~TCP_NAGLE_PUSH;
630 
631         tcp_slow_start_after_idle_check(sk);
632 }
633 
634 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
635 {
636         if (flags & MSG_OOB)
637                 tp->snd_up = tp->write_seq;
638 }
639 
640 /* If a not yet filled skb is pushed, do not send it if
641  * we have data packets in Qdisc or NIC queues :
642  * Because TX completion will happen shortly, it gives a chance
643  * to coalesce future sendmsg() payload into this skb, without
644  * need for a timer, and with no latency trade off.
645  * As packets containing data payload have a bigger truesize
646  * than pure acks (dataless) packets, the last checks prevent
647  * autocorking if we only have an ACK in Qdisc/NIC queues,
648  * or if TX completion was delayed after we processed ACK packet.
649  */
650 static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
651                                 int size_goal)
652 {
653         return skb->len < size_goal &&
654                sysctl_tcp_autocorking &&
655                skb != tcp_write_queue_head(sk) &&
656                atomic_read(&sk->sk_wmem_alloc) > skb->truesize;
657 }
658 
659 static void tcp_push(struct sock *sk, int flags, int mss_now,
660                      int nonagle, int size_goal)
661 {
662         struct tcp_sock *tp = tcp_sk(sk);
663         struct sk_buff *skb;
664 
665         if (!tcp_send_head(sk))
666                 return;
667 
668         skb = tcp_write_queue_tail(sk);
669         if (!(flags & MSG_MORE) || forced_push(tp))
670                 tcp_mark_push(tp, skb);
671 
672         tcp_mark_urg(tp, flags);
673 
674         if (tcp_should_autocork(sk, skb, size_goal)) {
675 
676                 /* avoid atomic op if TSQ_THROTTLED bit is already set */
677                 if (!test_bit(TSQ_THROTTLED, &tp->tsq_flags)) {
678                         NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTOCORKING);
679                         set_bit(TSQ_THROTTLED, &tp->tsq_flags);
680                 }
681                 /* It is possible TX completion already happened
682                  * before we set TSQ_THROTTLED.
683                  */
684                 if (atomic_read(&sk->sk_wmem_alloc) > skb->truesize)
685                         return;
686         }
687 
688         if (flags & MSG_MORE)
689                 nonagle = TCP_NAGLE_CORK;
690 
691         __tcp_push_pending_frames(sk, mss_now, nonagle);
692 }
693 
694 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
695                                 unsigned int offset, size_t len)
696 {
697         struct tcp_splice_state *tss = rd_desc->arg.data;
698         int ret;
699 
700         ret = skb_splice_bits(skb, skb->sk, offset, tss->pipe,
701                               min(rd_desc->count, len), tss->flags,
702                               skb_socket_splice);
703         if (ret > 0)
704                 rd_desc->count -= ret;
705         return ret;
706 }
707 
708 static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
709 {
710         /* Store TCP splice context information in read_descriptor_t. */
711         read_descriptor_t rd_desc = {
712                 .arg.data = tss,
713                 .count    = tss->len,
714         };
715 
716         return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
717 }
718 
719 /**
720  *  tcp_splice_read - splice data from TCP socket to a pipe
721  * @sock:       socket to splice from
722  * @ppos:       position (not valid)
723  * @pipe:       pipe to splice to
724  * @len:        number of bytes to splice
725  * @flags:      splice modifier flags
726  *
727  * Description:
728  *    Will read pages from given socket and fill them into a pipe.
729  *
730  **/
731 ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
732                         struct pipe_inode_info *pipe, size_t len,
733                         unsigned int flags)
734 {
735         struct sock *sk = sock->sk;
736         struct tcp_splice_state tss = {
737                 .pipe = pipe,
738                 .len = len,
739                 .flags = flags,
740         };
741         long timeo;
742         ssize_t spliced;
743         int ret;
744 
745         sock_rps_record_flow(sk);
746         /*
747          * We can't seek on a socket input
748          */
749         if (unlikely(*ppos))
750                 return -ESPIPE;
751 
752         ret = spliced = 0;
753 
754         lock_sock(sk);
755 
756         timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
757         while (tss.len) {
758                 ret = __tcp_splice_read(sk, &tss);
759                 if (ret < 0)
760                         break;
761                 else if (!ret) {
762                         if (spliced)
763                                 break;
764                         if (sock_flag(sk, SOCK_DONE))
765                                 break;
766                         if (sk->sk_err) {
767                                 ret = sock_error(sk);
768                                 break;
769                         }
770                         if (sk->sk_shutdown & RCV_SHUTDOWN)
771                                 break;
772                         if (sk->sk_state == TCP_CLOSE) {
773                                 /*
774                                  * This occurs when user tries to read
775                                  * from never connected socket.
776                                  */
777                                 if (!sock_flag(sk, SOCK_DONE))
778                                         ret = -ENOTCONN;
779                                 break;
780                         }
781                         if (!timeo) {
782                                 ret = -EAGAIN;
783                                 break;
784                         }
785                         sk_wait_data(sk, &timeo, NULL);
786                         if (signal_pending(current)) {
787                                 ret = sock_intr_errno(timeo);
788                                 break;
789                         }
790                         continue;
791                 }
792                 tss.len -= ret;
793                 spliced += ret;
794 
795                 if (!timeo)
796                         break;
797                 release_sock(sk);
798                 lock_sock(sk);
799 
800                 if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
801                     (sk->sk_shutdown & RCV_SHUTDOWN) ||
802                     signal_pending(current))
803                         break;
804         }
805 
806         release_sock(sk);
807 
808         if (spliced)
809                 return spliced;
810 
811         return ret;
812 }
813 EXPORT_SYMBOL(tcp_splice_read);
814 
815 struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
816                                     bool force_schedule)
817 {
818         struct sk_buff *skb;
819 
820         /* The TCP header must be at least 32-bit aligned.  */
821         size = ALIGN(size, 4);
822 
823         if (unlikely(tcp_under_memory_pressure(sk)))
824                 sk_mem_reclaim_partial(sk);
825 
826         skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
827         if (likely(skb)) {
828                 bool mem_scheduled;
829 
830                 if (force_schedule) {
831                         mem_scheduled = true;
832                         sk_forced_mem_schedule(sk, skb->truesize);
833                 } else {
834                         mem_scheduled = sk_wmem_schedule(sk, skb->truesize);
835                 }
836                 if (likely(mem_scheduled)) {
837                         skb_reserve(skb, sk->sk_prot->max_header);
838                         /*
839                          * Make sure that we have exactly size bytes
840                          * available to the caller, no more, no less.
841                          */
842                         skb->reserved_tailroom = skb->end - skb->tail - size;
843                         return skb;
844                 }
845                 __kfree_skb(skb);
846         } else {
847                 sk->sk_prot->enter_memory_pressure(sk);
848                 sk_stream_moderate_sndbuf(sk);
849         }
850         return NULL;
851 }
852 
853 static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
854                                        int large_allowed)
855 {
856         struct tcp_sock *tp = tcp_sk(sk);
857         u32 new_size_goal, size_goal;
858 
859         if (!large_allowed || !sk_can_gso(sk))
860                 return mss_now;
861 
862         /* Note : tcp_tso_autosize() will eventually split this later */
863         new_size_goal = sk->sk_gso_max_size - 1 - MAX_TCP_HEADER;
864         new_size_goal = tcp_bound_to_half_wnd(tp, new_size_goal);
865 
866         /* We try hard to avoid divides here */
867         size_goal = tp->gso_segs * mss_now;
868         if (unlikely(new_size_goal < size_goal ||
869                      new_size_goal >= size_goal + mss_now)) {
870                 tp->gso_segs = min_t(u16, new_size_goal / mss_now,
871                                      sk->sk_gso_max_segs);
872                 size_goal = tp->gso_segs * mss_now;
873         }
874 
875         return max(size_goal, mss_now);
876 }
877 
878 static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
879 {
880         int mss_now;
881 
882         mss_now = tcp_current_mss(sk);
883         *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
884 
885         return mss_now;
886 }
887 
888 static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
889                                 size_t size, int flags)
890 {
891         struct tcp_sock *tp = tcp_sk(sk);
892         int mss_now, size_goal;
893         int err;
894         ssize_t copied;
895         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
896 
897         /* Wait for a connection to finish. One exception is TCP Fast Open
898          * (passive side) where data is allowed to be sent before a connection
899          * is fully established.
900          */
901         if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
902             !tcp_passive_fastopen(sk)) {
903                 err = sk_stream_wait_connect(sk, &timeo);
904                 if (err != 0)
905                         goto out_err;
906         }
907 
908         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
909 
910         mss_now = tcp_send_mss(sk, &size_goal, flags);
911         copied = 0;
912 
913         err = -EPIPE;
914         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
915                 goto out_err;
916 
917         while (size > 0) {
918                 struct sk_buff *skb = tcp_write_queue_tail(sk);
919                 int copy, i;
920                 bool can_coalesce;
921 
922                 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
923 new_segment:
924                         if (!sk_stream_memory_free(sk))
925                                 goto wait_for_sndbuf;
926 
927                         skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation,
928                                                   skb_queue_empty(&sk->sk_write_queue));
929                         if (!skb)
930                                 goto wait_for_memory;
931 
932                         skb_entail(sk, skb);
933                         copy = size_goal;
934                 }
935 
936                 if (copy > size)
937                         copy = size;
938 
939                 i = skb_shinfo(skb)->nr_frags;
940                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
941                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
942                         tcp_mark_push(tp, skb);
943                         goto new_segment;
944                 }
945                 if (!sk_wmem_schedule(sk, copy))
946                         goto wait_for_memory;
947 
948                 if (can_coalesce) {
949                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
950                 } else {
951                         get_page(page);
952                         skb_fill_page_desc(skb, i, page, offset, copy);
953                 }
954                 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
955 
956                 skb->len += copy;
957                 skb->data_len += copy;
958                 skb->truesize += copy;
959                 sk->sk_wmem_queued += copy;
960                 sk_mem_charge(sk, copy);
961                 skb->ip_summed = CHECKSUM_PARTIAL;
962                 tp->write_seq += copy;
963                 TCP_SKB_CB(skb)->end_seq += copy;
964                 tcp_skb_pcount_set(skb, 0);
965 
966                 if (!copied)
967                         TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
968 
969                 copied += copy;
970                 offset += copy;
971                 size -= copy;
972                 if (!size) {
973                         tcp_tx_timestamp(sk, skb);
974                         goto out;
975                 }
976 
977                 if (skb->len < size_goal || (flags & MSG_OOB))
978                         continue;
979 
980                 if (forced_push(tp)) {
981                         tcp_mark_push(tp, skb);
982                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
983                 } else if (skb == tcp_send_head(sk))
984                         tcp_push_one(sk, mss_now);
985                 continue;
986 
987 wait_for_sndbuf:
988                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
989 wait_for_memory:
990                 tcp_push(sk, flags & ~MSG_MORE, mss_now,
991                          TCP_NAGLE_PUSH, size_goal);
992 
993                 err = sk_stream_wait_memory(sk, &timeo);
994                 if (err != 0)
995                         goto do_error;
996 
997                 mss_now = tcp_send_mss(sk, &size_goal, flags);
998         }
999 
1000 out:
1001         if (copied && !(flags & MSG_SENDPAGE_NOTLAST))
1002                 tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
1003         return copied;
1004 
1005 do_error:
1006         if (copied)
1007                 goto out;
1008 out_err:
1009         /* make sure we wake any epoll edge trigger waiter */
1010         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1011                 sk->sk_write_space(sk);
1012         return sk_stream_error(sk, flags, err);
1013 }
1014 
1015 int tcp_sendpage(struct sock *sk, struct page *page, int offset,
1016                  size_t size, int flags)
1017 {
1018         ssize_t res;
1019 
1020         if (!(sk->sk_route_caps & NETIF_F_SG) ||
1021             !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
1022                 return sock_no_sendpage(sk->sk_socket, page, offset, size,
1023                                         flags);
1024 
1025         lock_sock(sk);
1026         res = do_tcp_sendpages(sk, page, offset, size, flags);
1027         release_sock(sk);
1028         return res;
1029 }
1030 EXPORT_SYMBOL(tcp_sendpage);
1031 
1032 static inline int select_size(const struct sock *sk, bool sg)
1033 {
1034         const struct tcp_sock *tp = tcp_sk(sk);
1035         int tmp = tp->mss_cache;
1036 
1037         if (sg) {
1038                 if (sk_can_gso(sk)) {
1039                         /* Small frames wont use a full page:
1040                          * Payload will immediately follow tcp header.
1041                          */
1042                         tmp = SKB_WITH_OVERHEAD(2048 - MAX_TCP_HEADER);
1043                 } else {
1044                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
1045 
1046                         if (tmp >= pgbreak &&
1047                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
1048                                 tmp = pgbreak;
1049                 }
1050         }
1051 
1052         return tmp;
1053 }
1054 
1055 void tcp_free_fastopen_req(struct tcp_sock *tp)
1056 {
1057         if (tp->fastopen_req) {
1058                 kfree(tp->fastopen_req);
1059                 tp->fastopen_req = NULL;
1060         }
1061 }
1062 
1063 static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
1064                                 int *copied, size_t size)
1065 {
1066         struct tcp_sock *tp = tcp_sk(sk);
1067         int err, flags;
1068 
1069         if (!(sysctl_tcp_fastopen & TFO_CLIENT_ENABLE))
1070                 return -EOPNOTSUPP;
1071         if (tp->fastopen_req)
1072                 return -EALREADY; /* Another Fast Open is in progress */
1073 
1074         tp->fastopen_req = kzalloc(sizeof(struct tcp_fastopen_request),
1075                                    sk->sk_allocation);
1076         if (unlikely(!tp->fastopen_req))
1077                 return -ENOBUFS;
1078         tp->fastopen_req->data = msg;
1079         tp->fastopen_req->size = size;
1080 
1081         flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
1082         err = __inet_stream_connect(sk->sk_socket, msg->msg_name,
1083                                     msg->msg_namelen, flags);
1084         *copied = tp->fastopen_req->copied;
1085         tcp_free_fastopen_req(tp);
1086         return err;
1087 }
1088 
1089 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
1090 {
1091         struct tcp_sock *tp = tcp_sk(sk);
1092         struct sk_buff *skb;
1093         int flags, err, copied = 0;
1094         int mss_now = 0, size_goal, copied_syn = 0;
1095         bool sg;
1096         long timeo;
1097 
1098         lock_sock(sk);
1099 
1100         flags = msg->msg_flags;
1101         if (flags & MSG_FASTOPEN) {
1102                 err = tcp_sendmsg_fastopen(sk, msg, &copied_syn, size);
1103                 if (err == -EINPROGRESS && copied_syn > 0)
1104                         goto out;
1105                 else if (err)
1106                         goto out_err;
1107         }
1108 
1109         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
1110 
1111         /* Wait for a connection to finish. One exception is TCP Fast Open
1112          * (passive side) where data is allowed to be sent before a connection
1113          * is fully established.
1114          */
1115         if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
1116             !tcp_passive_fastopen(sk)) {
1117                 err = sk_stream_wait_connect(sk, &timeo);
1118                 if (err != 0)
1119                         goto do_error;
1120         }
1121 
1122         if (unlikely(tp->repair)) {
1123                 if (tp->repair_queue == TCP_RECV_QUEUE) {
1124                         copied = tcp_send_rcvq(sk, msg, size);
1125                         goto out_nopush;
1126                 }
1127 
1128                 err = -EINVAL;
1129                 if (tp->repair_queue == TCP_NO_QUEUE)
1130                         goto out_err;
1131 
1132                 /* 'common' sending to sendq */
1133         }
1134 
1135         /* This should be in poll */
1136         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
1137 
1138         mss_now = tcp_send_mss(sk, &size_goal, flags);
1139 
1140         /* Ok commence sending. */
1141         copied = 0;
1142 
1143         err = -EPIPE;
1144         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
1145                 goto out_err;
1146 
1147         sg = !!(sk->sk_route_caps & NETIF_F_SG);
1148 
1149         while (msg_data_left(msg)) {
1150                 int copy = 0;
1151                 int max = size_goal;
1152 
1153                 skb = tcp_write_queue_tail(sk);
1154                 if (tcp_send_head(sk)) {
1155                         if (skb->ip_summed == CHECKSUM_NONE)
1156                                 max = mss_now;
1157                         copy = max - skb->len;
1158                 }
1159 
1160                 if (copy <= 0) {
1161 new_segment:
1162                         /* Allocate new segment. If the interface is SG,
1163                          * allocate skb fitting to single page.
1164                          */
1165                         if (!sk_stream_memory_free(sk))
1166                                 goto wait_for_sndbuf;
1167 
1168                         skb = sk_stream_alloc_skb(sk,
1169                                                   select_size(sk, sg),
1170                                                   sk->sk_allocation,
1171                                                   skb_queue_empty(&sk->sk_write_queue));
1172                         if (!skb)
1173                                 goto wait_for_memory;
1174 
1175                         /*
1176                          * Check whether we can use HW checksum.
1177                          */
1178                         if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
1179                                 skb->ip_summed = CHECKSUM_PARTIAL;
1180 
1181                         skb_entail(sk, skb);
1182                         copy = size_goal;
1183                         max = size_goal;
1184 
1185                         /* All packets are restored as if they have
1186                          * already been sent. skb_mstamp isn't set to
1187                          * avoid wrong rtt estimation.
1188                          */
1189                         if (tp->repair)
1190                                 TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
1191                 }
1192 
1193                 /* Try to append data to the end of skb. */
1194                 if (copy > msg_data_left(msg))
1195                         copy = msg_data_left(msg);
1196 
1197                 /* Where to copy to? */
1198                 if (skb_availroom(skb) > 0) {
1199                         /* We have some space in skb head. Superb! */
1200                         copy = min_t(int, copy, skb_availroom(skb));
1201                         err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);
1202                         if (err)
1203                                 goto do_fault;
1204                 } else {
1205                         bool merge = true;
1206                         int i = skb_shinfo(skb)->nr_frags;
1207                         struct page_frag *pfrag = sk_page_frag(sk);
1208 
1209                         if (!sk_page_frag_refill(sk, pfrag))
1210                                 goto wait_for_memory;
1211 
1212                         if (!skb_can_coalesce(skb, i, pfrag->page,
1213                                               pfrag->offset)) {
1214                                 if (i == MAX_SKB_FRAGS || !sg) {
1215                                         tcp_mark_push(tp, skb);
1216                                         goto new_segment;
1217                                 }
1218                                 merge = false;
1219                         }
1220 
1221                         copy = min_t(int, copy, pfrag->size - pfrag->offset);
1222 
1223                         if (!sk_wmem_schedule(sk, copy))
1224                                 goto wait_for_memory;
1225 
1226                         err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
1227                                                        pfrag->page,
1228                                                        pfrag->offset,
1229                                                        copy);
1230                         if (err)
1231                                 goto do_error;
1232 
1233                         /* Update the skb. */
1234                         if (merge) {
1235                                 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1236                         } else {
1237                                 skb_fill_page_desc(skb, i, pfrag->page,
1238                                                    pfrag->offset, copy);
1239                                 get_page(pfrag->page);
1240                         }
1241                         pfrag->offset += copy;
1242                 }
1243 
1244                 if (!copied)
1245                         TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1246 
1247                 tp->write_seq += copy;
1248                 TCP_SKB_CB(skb)->end_seq += copy;
1249                 tcp_skb_pcount_set(skb, 0);
1250 
1251                 copied += copy;
1252                 if (!msg_data_left(msg)) {
1253                         tcp_tx_timestamp(sk, skb);
1254                         goto out;
1255                 }
1256 
1257                 if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
1258                         continue;
1259 
1260                 if (forced_push(tp)) {
1261                         tcp_mark_push(tp, skb);
1262                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1263                 } else if (skb == tcp_send_head(sk))
1264                         tcp_push_one(sk, mss_now);
1265                 continue;
1266 
1267 wait_for_sndbuf:
1268                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1269 wait_for_memory:
1270                 if (copied)
1271                         tcp_push(sk, flags & ~MSG_MORE, mss_now,
1272                                  TCP_NAGLE_PUSH, size_goal);
1273 
1274                 err = sk_stream_wait_memory(sk, &timeo);
1275                 if (err != 0)
1276                         goto do_error;
1277 
1278                 mss_now = tcp_send_mss(sk, &size_goal, flags);
1279         }
1280 
1281 out:
1282         if (copied)
1283                 tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
1284 out_nopush:
1285         release_sock(sk);
1286         return copied + copied_syn;
1287 
1288 do_fault:
1289         if (!skb->len) {
1290                 tcp_unlink_write_queue(skb, sk);
1291                 /* It is the one place in all of TCP, except connection
1292                  * reset, where we can be unlinking the send_head.
1293                  */
1294                 tcp_check_send_head(sk, skb);
1295                 sk_wmem_free_skb(sk, skb);
1296         }
1297 
1298 do_error:
1299         if (copied + copied_syn)
1300                 goto out;
1301 out_err:
1302         err = sk_stream_error(sk, flags, err);
1303         /* make sure we wake any epoll edge trigger waiter */
1304         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1305                 sk->sk_write_space(sk);
1306         release_sock(sk);
1307         return err;
1308 }
1309 EXPORT_SYMBOL(tcp_sendmsg);
1310 
1311 /*
1312  *      Handle reading urgent data. BSD has very simple semantics for
1313  *      this, no blocking and very strange errors 8)
1314  */
1315 
1316 static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1317 {
1318         struct tcp_sock *tp = tcp_sk(sk);
1319 
1320         /* No URG data to read. */
1321         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1322             tp->urg_data == TCP_URG_READ)
1323                 return -EINVAL; /* Yes this is right ! */
1324 
1325         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1326                 return -ENOTCONN;
1327 
1328         if (tp->urg_data & TCP_URG_VALID) {
1329                 int err = 0;
1330                 char c = tp->urg_data;
1331 
1332                 if (!(flags & MSG_PEEK))
1333                         tp->urg_data = TCP_URG_READ;
1334 
1335                 /* Read urgent data. */
1336                 msg->msg_flags |= MSG_OOB;
1337 
1338                 if (len > 0) {
1339                         if (!(flags & MSG_TRUNC))
1340                                 err = memcpy_to_msg(msg, &c, 1);
1341                         len = 1;
1342                 } else
1343                         msg->msg_flags |= MSG_TRUNC;
1344 
1345                 return err ? -EFAULT : len;
1346         }
1347 
1348         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1349                 return 0;
1350 
1351         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1352          * the available implementations agree in this case:
1353          * this call should never block, independent of the
1354          * blocking state of the socket.
1355          * Mike <pall@rz.uni-karlsruhe.de>
1356          */
1357         return -EAGAIN;
1358 }
1359 
1360 static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len)
1361 {
1362         struct sk_buff *skb;
1363         int copied = 0, err = 0;
1364 
1365         /* XXX -- need to support SO_PEEK_OFF */
1366 
1367         skb_queue_walk(&sk->sk_write_queue, skb) {
1368                 err = skb_copy_datagram_msg(skb, 0, msg, skb->len);
1369                 if (err)
1370                         break;
1371 
1372                 copied += skb->len;
1373         }
1374 
1375         return err ?: copied;
1376 }
1377 
1378 /* Clean up the receive buffer for full frames taken by the user,
1379  * then send an ACK if necessary.  COPIED is the number of bytes
1380  * tcp_recvmsg has given to the user so far, it speeds up the
1381  * calculation of whether or not we must ACK for the sake of
1382  * a window update.
1383  */
1384 static void tcp_cleanup_rbuf(struct sock *sk, int copied)
1385 {
1386         struct tcp_sock *tp = tcp_sk(sk);
1387         bool time_to_ack = false;
1388 
1389         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1390 
1391         WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1392              "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1393              tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1394 
1395         if (inet_csk_ack_scheduled(sk)) {
1396                 const struct inet_connection_sock *icsk = inet_csk(sk);
1397                    /* Delayed ACKs frequently hit locked sockets during bulk
1398                     * receive. */
1399                 if (icsk->icsk_ack.blocked ||
1400                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
1401                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1402                     /*
1403                      * If this read emptied read buffer, we send ACK, if
1404                      * connection is not bidirectional, user drained
1405                      * receive buffer and there was a small segment
1406                      * in queue.
1407                      */
1408                     (copied > 0 &&
1409                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1410                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1411                        !icsk->icsk_ack.pingpong)) &&
1412                       !atomic_read(&sk->sk_rmem_alloc)))
1413                         time_to_ack = true;
1414         }
1415 
1416         /* We send an ACK if we can now advertise a non-zero window
1417          * which has been raised "significantly".
1418          *
1419          * Even if window raised up to infinity, do not send window open ACK
1420          * in states, where we will not receive more. It is useless.
1421          */
1422         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1423                 __u32 rcv_window_now = tcp_receive_window(tp);
1424 
1425                 /* Optimize, __tcp_select_window() is not cheap. */
1426                 if (2*rcv_window_now <= tp->window_clamp) {
1427                         __u32 new_window = __tcp_select_window(sk);
1428 
1429                         /* Send ACK now, if this read freed lots of space
1430                          * in our buffer. Certainly, new_window is new window.
1431                          * We can advertise it now, if it is not less than current one.
1432                          * "Lots" means "at least twice" here.
1433                          */
1434                         if (new_window && new_window >= 2 * rcv_window_now)
1435                                 time_to_ack = true;
1436                 }
1437         }
1438         if (time_to_ack)
1439                 tcp_send_ack(sk);
1440 }
1441 
1442 static void tcp_prequeue_process(struct sock *sk)
1443 {
1444         struct sk_buff *skb;
1445         struct tcp_sock *tp = tcp_sk(sk);
1446 
1447         NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1448 
1449         /* RX process wants to run with disabled BHs, though it is not
1450          * necessary */
1451         local_bh_disable();
1452         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1453                 sk_backlog_rcv(sk, skb);
1454         local_bh_enable();
1455 
1456         /* Clear memory counter. */
1457         tp->ucopy.memory = 0;
1458 }
1459 
1460 static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1461 {
1462         struct sk_buff *skb;
1463         u32 offset;
1464 
1465         while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
1466                 offset = seq - TCP_SKB_CB(skb)->seq;
1467                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
1468                         offset--;
1469                 if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {
1470                         *off = offset;
1471                         return skb;
1472                 }
1473                 /* This looks weird, but this can happen if TCP collapsing
1474                  * splitted a fat GRO packet, while we released socket lock
1475                  * in skb_splice_bits()
1476                  */
1477                 sk_eat_skb(sk, skb);
1478         }
1479         return NULL;
1480 }
1481 
1482 /*
1483  * This routine provides an alternative to tcp_recvmsg() for routines
1484  * that would like to handle copying from skbuffs directly in 'sendfile'
1485  * fashion.
1486  * Note:
1487  *      - It is assumed that the socket was locked by the caller.
1488  *      - The routine does not block.
1489  *      - At present, there is no support for reading OOB data
1490  *        or for 'peeking' the socket using this routine
1491  *        (although both would be easy to implement).
1492  */
1493 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1494                   sk_read_actor_t recv_actor)
1495 {
1496         struct sk_buff *skb;
1497         struct tcp_sock *tp = tcp_sk(sk);
1498         u32 seq = tp->copied_seq;
1499         u32 offset;
1500         int copied = 0;
1501 
1502         if (sk->sk_state == TCP_LISTEN)
1503                 return -ENOTCONN;
1504         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1505                 if (offset < skb->len) {
1506                         int used;
1507                         size_t len;
1508 
1509                         len = skb->len - offset;
1510                         /* Stop reading if we hit a patch of urgent data */
1511                         if (tp->urg_data) {
1512                                 u32 urg_offset = tp->urg_seq - seq;
1513                                 if (urg_offset < len)
1514                                         len = urg_offset;
1515                                 if (!len)
1516                                         break;
1517                         }
1518                         used = recv_actor(desc, skb, offset, len);
1519                         if (used <= 0) {
1520                                 if (!copied)
1521                                         copied = used;
1522                                 break;
1523                         } else if (used <= len) {
1524                                 seq += used;
1525                                 copied += used;
1526                                 offset += used;
1527                         }
1528                         /* If recv_actor drops the lock (e.g. TCP splice
1529                          * receive) the skb pointer might be invalid when
1530                          * getting here: tcp_collapse might have deleted it
1531                          * while aggregating skbs from the socket queue.
1532                          */
1533                         skb = tcp_recv_skb(sk, seq - 1, &offset);
1534                         if (!skb)
1535                                 break;
1536                         /* TCP coalescing might have appended data to the skb.
1537                          * Try to splice more frags
1538                          */
1539                         if (offset + 1 != skb->len)
1540                                 continue;
1541                 }
1542                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
1543                         sk_eat_skb(sk, skb);
1544                         ++seq;
1545                         break;
1546                 }
1547                 sk_eat_skb(sk, skb);
1548                 if (!desc->count)
1549                         break;
1550                 tp->copied_seq = seq;
1551         }
1552         tp->copied_seq = seq;
1553 
1554         tcp_rcv_space_adjust(sk);
1555 
1556         /* Clean up data we have read: This will do ACK frames. */
1557         if (copied > 0) {
1558                 tcp_recv_skb(sk, seq, &offset);
1559                 tcp_cleanup_rbuf(sk, copied);
1560         }
1561         return copied;
1562 }
1563 EXPORT_SYMBOL(tcp_read_sock);
1564 
1565 /*
1566  *      This routine copies from a sock struct into the user buffer.
1567  *
1568  *      Technical note: in 2.3 we work on _locked_ socket, so that
1569  *      tricks with *seq access order and skb->users are not required.
1570  *      Probably, code can be easily improved even more.
1571  */
1572 
1573 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
1574                 int flags, int *addr_len)
1575 {
1576         struct tcp_sock *tp = tcp_sk(sk);
1577         int copied = 0;
1578         u32 peek_seq;
1579         u32 *seq;
1580         unsigned long used;
1581         int err;
1582         int target;             /* Read at least this many bytes */
1583         long timeo;
1584         struct task_struct *user_recv = NULL;
1585         struct sk_buff *skb, *last;
1586         u32 urg_hole = 0;
1587 
1588         if (unlikely(flags & MSG_ERRQUEUE))
1589                 return inet_recv_error(sk, msg, len, addr_len);
1590 
1591         if (sk_can_busy_loop(sk) && skb_queue_empty(&sk->sk_receive_queue) &&
1592             (sk->sk_state == TCP_ESTABLISHED))
1593                 sk_busy_loop(sk, nonblock);
1594 
1595         lock_sock(sk);
1596 
1597         err = -ENOTCONN;
1598         if (sk->sk_state == TCP_LISTEN)
1599                 goto out;
1600 
1601         timeo = sock_rcvtimeo(sk, nonblock);
1602 
1603         /* Urgent data needs to be handled specially. */
1604         if (flags & MSG_OOB)
1605                 goto recv_urg;
1606 
1607         if (unlikely(tp->repair)) {
1608                 err = -EPERM;
1609                 if (!(flags & MSG_PEEK))
1610                         goto out;
1611 
1612                 if (tp->repair_queue == TCP_SEND_QUEUE)
1613                         goto recv_sndq;
1614 
1615                 err = -EINVAL;
1616                 if (tp->repair_queue == TCP_NO_QUEUE)
1617                         goto out;
1618 
1619                 /* 'common' recv queue MSG_PEEK-ing */
1620         }
1621 
1622         seq = &tp->copied_seq;
1623         if (flags & MSG_PEEK) {
1624                 peek_seq = tp->copied_seq;
1625                 seq = &peek_seq;
1626         }
1627 
1628         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1629 
1630         do {
1631                 u32 offset;
1632 
1633                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1634                 if (tp->urg_data && tp->urg_seq == *seq) {
1635                         if (copied)
1636                                 break;
1637                         if (signal_pending(current)) {
1638                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1639                                 break;
1640                         }
1641                 }
1642 
1643                 /* Next get a buffer. */
1644 
1645                 last = skb_peek_tail(&sk->sk_receive_queue);
1646                 skb_queue_walk(&sk->sk_receive_queue, skb) {
1647                         last = skb;
1648                         /* Now that we have two receive queues this
1649                          * shouldn't happen.
1650                          */
1651                         if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
1652                                  "recvmsg bug: copied %X seq %X rcvnxt %X fl %X\n",
1653                                  *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
1654                                  flags))
1655                                 break;
1656 
1657                         offset = *seq - TCP_SKB_CB(skb)->seq;
1658                         if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
1659                                 offset--;
1660                         if (offset < skb->len)
1661                                 goto found_ok_skb;
1662                         if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
1663                                 goto found_fin_ok;
1664                         WARN(!(flags & MSG_PEEK),
1665                              "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n",
1666                              *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
1667                 }
1668 
1669                 /* Well, if we have backlog, try to process it now yet. */
1670 
1671                 if (copied >= target && !sk->sk_backlog.tail)
1672                         break;
1673 
1674                 if (copied) {
1675                         if (sk->sk_err ||
1676                             sk->sk_state == TCP_CLOSE ||
1677                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1678                             !timeo ||
1679                             signal_pending(current))
1680                                 break;
1681                 } else {
1682                         if (sock_flag(sk, SOCK_DONE))
1683                                 break;
1684 
1685                         if (sk->sk_err) {
1686                                 copied = sock_error(sk);
1687                                 break;
1688                         }
1689 
1690                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1691                                 break;
1692 
1693                         if (sk->sk_state == TCP_CLOSE) {
1694                                 if (!sock_flag(sk, SOCK_DONE)) {
1695                                         /* This occurs when user tries to read
1696                                          * from never connected socket.
1697                                          */
1698                                         copied = -ENOTCONN;
1699                                         break;
1700                                 }
1701                                 break;
1702                         }
1703 
1704                         if (!timeo) {
1705                                 copied = -EAGAIN;
1706                                 break;
1707                         }
1708 
1709                         if (signal_pending(current)) {
1710                                 copied = sock_intr_errno(timeo);
1711                                 break;
1712                         }
1713                 }
1714 
1715                 tcp_cleanup_rbuf(sk, copied);
1716 
1717                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1718                         /* Install new reader */
1719                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1720                                 user_recv = current;
1721                                 tp->ucopy.task = user_recv;
1722                                 tp->ucopy.msg = msg;
1723                         }
1724 
1725                         tp->ucopy.len = len;
1726 
1727                         WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1728                                 !(flags & (MSG_PEEK | MSG_TRUNC)));
1729 
1730                         /* Ugly... If prequeue is not empty, we have to
1731                          * process it before releasing socket, otherwise
1732                          * order will be broken at second iteration.
1733                          * More elegant solution is required!!!
1734                          *
1735                          * Look: we have the following (pseudo)queues:
1736                          *
1737                          * 1. packets in flight
1738                          * 2. backlog
1739                          * 3. prequeue
1740                          * 4. receive_queue
1741                          *
1742                          * Each queue can be processed only if the next ones
1743                          * are empty. At this point we have empty receive_queue.
1744                          * But prequeue _can_ be not empty after 2nd iteration,
1745                          * when we jumped to start of loop because backlog
1746                          * processing added something to receive_queue.
1747                          * We cannot release_sock(), because backlog contains
1748                          * packets arrived _after_ prequeued ones.
1749                          *
1750                          * Shortly, algorithm is clear --- to process all
1751                          * the queues in order. We could make it more directly,
1752                          * requeueing packets from backlog to prequeue, if
1753                          * is not empty. It is more elegant, but eats cycles,
1754                          * unfortunately.
1755                          */
1756                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1757                                 goto do_prequeue;
1758 
1759                         /* __ Set realtime policy in scheduler __ */
1760                 }
1761 
1762                 if (copied >= target) {
1763                         /* Do not sleep, just process backlog. */
1764                         release_sock(sk);
1765                         lock_sock(sk);
1766                 } else {
1767                         sk_wait_data(sk, &timeo, last);
1768                 }
1769 
1770                 if (user_recv) {
1771                         int chunk;
1772 
1773                         /* __ Restore normal policy in scheduler __ */
1774 
1775                         chunk = len - tp->ucopy.len;
1776                         if (chunk != 0) {
1777                                 NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1778                                 len -= chunk;
1779                                 copied += chunk;
1780                         }
1781 
1782                         if (tp->rcv_nxt == tp->copied_seq &&
1783                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1784 do_prequeue:
1785                                 tcp_prequeue_process(sk);
1786 
1787                                 chunk = len - tp->ucopy.len;
1788                                 if (chunk != 0) {
1789                                         NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1790                                         len -= chunk;
1791                                         copied += chunk;
1792                                 }
1793                         }
1794                 }
1795                 if ((flags & MSG_PEEK) &&
1796                     (peek_seq - copied - urg_hole != tp->copied_seq)) {
1797                         net_dbg_ratelimited("TCP(%s:%d): Application bug, race in MSG_PEEK\n",
1798                                             current->comm,
1799                                             task_pid_nr(current));
1800                         peek_seq = tp->copied_seq;
1801                 }
1802                 continue;
1803 
1804         found_ok_skb:
1805                 /* Ok so how much can we use? */
1806                 used = skb->len - offset;
1807                 if (len < used)
1808                         used = len;
1809 
1810                 /* Do we have urgent data here? */
1811                 if (tp->urg_data) {
1812                         u32 urg_offset = tp->urg_seq - *seq;
1813                         if (urg_offset < used) {
1814                                 if (!urg_offset) {
1815                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1816                                                 ++*seq;
1817                                                 urg_hole++;
1818                                                 offset++;
1819                                                 used--;
1820                                                 if (!used)
1821                                                         goto skip_copy;
1822                                         }
1823                                 } else
1824                                         used = urg_offset;
1825                         }
1826                 }
1827 
1828                 if (!(flags & MSG_TRUNC)) {
1829                         err = skb_copy_datagram_msg(skb, offset, msg, used);
1830                         if (err) {
1831                                 /* Exception. Bailout! */
1832                                 if (!copied)
1833                                         copied = -EFAULT;
1834                                 break;
1835                         }
1836                 }
1837 
1838                 *seq += used;
1839                 copied += used;
1840                 len -= used;
1841 
1842                 tcp_rcv_space_adjust(sk);
1843 
1844 skip_copy:
1845                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1846                         tp->urg_data = 0;
1847                         tcp_fast_path_check(sk);
1848                 }
1849                 if (used + offset < skb->len)
1850                         continue;
1851 
1852                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
1853                         goto found_fin_ok;
1854                 if (!(flags & MSG_PEEK))
1855                         sk_eat_skb(sk, skb);
1856                 continue;
1857 
1858         found_fin_ok:
1859                 /* Process the FIN. */
1860                 ++*seq;
1861                 if (!(flags & MSG_PEEK))
1862                         sk_eat_skb(sk, skb);
1863                 break;
1864         } while (len > 0);
1865 
1866         if (user_recv) {
1867                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1868                         int chunk;
1869 
1870                         tp->ucopy.len = copied > 0 ? len : 0;
1871 
1872                         tcp_prequeue_process(sk);
1873 
1874                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1875                                 NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1876                                 len -= chunk;
1877                                 copied += chunk;
1878                         }
1879                 }
1880 
1881                 tp->ucopy.task = NULL;
1882                 tp->ucopy.len = 0;
1883         }
1884 
1885         /* According to UNIX98, msg_name/msg_namelen are ignored
1886          * on connected socket. I was just happy when found this 8) --ANK
1887          */
1888 
1889         /* Clean up data we have read: This will do ACK frames. */
1890         tcp_cleanup_rbuf(sk, copied);
1891 
1892         release_sock(sk);
1893         return copied;
1894 
1895 out:
1896         release_sock(sk);
1897         return err;
1898 
1899 recv_urg:
1900         err = tcp_recv_urg(sk, msg, len, flags);
1901         goto out;
1902 
1903 recv_sndq:
1904         err = tcp_peek_sndq(sk, msg, len);
1905         goto out;
1906 }
1907 EXPORT_SYMBOL(tcp_recvmsg);
1908 
1909 void tcp_set_state(struct sock *sk, int state)
1910 {
1911         int oldstate = sk->sk_state;
1912 
1913         switch (state) {
1914         case TCP_ESTABLISHED:
1915                 if (oldstate != TCP_ESTABLISHED)
1916                         TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1917                 break;
1918 
1919         case TCP_CLOSE:
1920                 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1921                         TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1922 
1923                 sk->sk_prot->unhash(sk);
1924                 if (inet_csk(sk)->icsk_bind_hash &&
1925                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1926                         inet_put_port(sk);
1927                 /* fall through */
1928         default:
1929                 if (oldstate == TCP_ESTABLISHED)
1930                         TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1931         }
1932 
1933         /* Change state AFTER socket is unhashed to avoid closed
1934          * socket sitting in hash tables.
1935          */
1936         sk_state_store(sk, state);
1937 
1938 #ifdef STATE_TRACE
1939         SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1940 #endif
1941 }
1942 EXPORT_SYMBOL_GPL(tcp_set_state);
1943 
1944 /*
1945  *      State processing on a close. This implements the state shift for
1946  *      sending our FIN frame. Note that we only send a FIN for some
1947  *      states. A shutdown() may have already sent the FIN, or we may be
1948  *      closed.
1949  */
1950 
1951 static const unsigned char new_state[16] = {
1952   /* current state:        new state:      action:      */
1953   [0 /* (Invalid) */]   = TCP_CLOSE,
1954   [TCP_ESTABLISHED]     = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1955   [TCP_SYN_SENT]        = TCP_CLOSE,
1956   [TCP_SYN_RECV]        = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1957   [TCP_FIN_WAIT1]       = TCP_FIN_WAIT1,
1958   [TCP_FIN_WAIT2]       = TCP_FIN_WAIT2,
1959   [TCP_TIME_WAIT]       = TCP_CLOSE,
1960   [TCP_CLOSE]           = TCP_CLOSE,
1961   [TCP_CLOSE_WAIT]      = TCP_LAST_ACK  | TCP_ACTION_FIN,
1962   [TCP_LAST_ACK]        = TCP_LAST_ACK,
1963   [TCP_LISTEN]          = TCP_CLOSE,
1964   [TCP_CLOSING]         = TCP_CLOSING,
1965   [TCP_NEW_SYN_RECV]    = TCP_CLOSE,    /* should not happen ! */
1966 };
1967 
1968 static int tcp_close_state(struct sock *sk)
1969 {
1970         int next = (int)new_state[sk->sk_state];
1971         int ns = next & TCP_STATE_MASK;
1972 
1973         tcp_set_state(sk, ns);
1974 
1975         return next & TCP_ACTION_FIN;
1976 }
1977 
1978 /*
1979  *      Shutdown the sending side of a connection. Much like close except
1980  *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1981  */
1982 
1983 void tcp_shutdown(struct sock *sk, int how)
1984 {
1985         /*      We need to grab some memory, and put together a FIN,
1986          *      and then put it into the queue to be sent.
1987          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1988          */
1989         if (!(how & SEND_SHUTDOWN))
1990                 return;
1991 
1992         /* If we've already sent a FIN, or it's a closed state, skip this. */
1993         if ((1 << sk->sk_state) &
1994             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1995              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1996                 /* Clear out any half completed packets.  FIN if needed. */
1997                 if (tcp_close_state(sk))
1998                         tcp_send_fin(sk);
1999         }
2000 }
2001 EXPORT_SYMBOL(tcp_shutdown);
2002 
2003 bool tcp_check_oom(struct sock *sk, int shift)
2004 {
2005         bool too_many_orphans, out_of_socket_memory;
2006 
2007         too_many_orphans = tcp_too_many_orphans(sk, shift);
2008         out_of_socket_memory = tcp_out_of_memory(sk);
2009 
2010         if (too_many_orphans)
2011                 net_info_ratelimited("too many orphaned sockets\n");
2012         if (out_of_socket_memory)
2013                 net_info_ratelimited("out of memory -- consider tuning tcp_mem\n");
2014         return too_many_orphans || out_of_socket_memory;
2015 }
2016 
2017 void tcp_close(struct sock *sk, long timeout)
2018 {
2019         struct sk_buff *skb;
2020         int data_was_unread = 0;
2021         int state;
2022 
2023         lock_sock(sk);
2024         sk->sk_shutdown = SHUTDOWN_MASK;
2025 
2026         if (sk->sk_state == TCP_LISTEN) {
2027                 tcp_set_state(sk, TCP_CLOSE);
2028 
2029                 /* Special case. */
2030                 inet_csk_listen_stop(sk);
2031 
2032                 goto adjudge_to_death;
2033         }
2034 
2035         /*  We need to flush the recv. buffs.  We do this only on the
2036          *  descriptor close, not protocol-sourced closes, because the
2037          *  reader process may not have drained the data yet!
2038          */
2039         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
2040                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq;
2041 
2042                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
2043                         len--;
2044                 data_was_unread += len;
2045                 __kfree_skb(skb);
2046         }
2047 
2048         sk_mem_reclaim(sk);
2049 
2050         /* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
2051         if (sk->sk_state == TCP_CLOSE)
2052                 goto adjudge_to_death;
2053 
2054         /* As outlined in RFC 2525, section 2.17, we send a RST here because
2055          * data was lost. To witness the awful effects of the old behavior of
2056          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
2057          * GET in an FTP client, suspend the process, wait for the client to
2058          * advertise a zero window, then kill -9 the FTP client, wheee...
2059          * Note: timeout is always zero in such a case.
2060          */
2061         if (unlikely(tcp_sk(sk)->repair)) {
2062                 sk->sk_prot->disconnect(sk, 0);
2063         } else if (data_was_unread) {
2064                 /* Unread data was tossed, zap the connection. */
2065                 NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
2066                 tcp_set_state(sk, TCP_CLOSE);
2067                 tcp_send_active_reset(sk, sk->sk_allocation);
2068         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
2069                 /* Check zero linger _after_ checking for unread data. */
2070                 sk->sk_prot->disconnect(sk, 0);
2071                 NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
2072         } else if (tcp_close_state(sk)) {
2073                 /* We FIN if the application ate all the data before
2074                  * zapping the connection.
2075                  */
2076 
2077                 /* RED-PEN. Formally speaking, we have broken TCP state
2078                  * machine. State transitions:
2079                  *
2080                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
2081                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
2082                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
2083                  *
2084                  * are legal only when FIN has been sent (i.e. in window),
2085                  * rather than queued out of window. Purists blame.
2086                  *
2087                  * F.e. "RFC state" is ESTABLISHED,
2088                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
2089                  *
2090                  * The visible declinations are that sometimes
2091                  * we enter time-wait state, when it is not required really
2092                  * (harmless), do not send active resets, when they are
2093                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
2094                  * they look as CLOSING or LAST_ACK for Linux)
2095                  * Probably, I missed some more holelets.
2096                  *                                              --ANK
2097                  * XXX (TFO) - To start off we don't support SYN+ACK+FIN
2098                  * in a single packet! (May consider it later but will
2099                  * probably need API support or TCP_CORK SYN-ACK until
2100                  * data is written and socket is closed.)
2101                  */
2102                 tcp_send_fin(sk);
2103         }
2104 
2105         sk_stream_wait_close(sk, timeout);
2106 
2107 adjudge_to_death:
2108         state = sk->sk_state;
2109         sock_hold(sk);
2110         sock_orphan(sk);
2111 
2112         /* It is the last release_sock in its life. It will remove backlog. */
2113         release_sock(sk);
2114 
2115 
2116         /* Now socket is owned by kernel and we acquire BH lock
2117            to finish close. No need to check for user refs.
2118          */
2119         local_bh_disable();
2120         bh_lock_sock(sk);
2121         WARN_ON(sock_owned_by_user(sk));
2122 
2123         percpu_counter_inc(sk->sk_prot->orphan_count);
2124 
2125         /* Have we already been destroyed by a softirq or backlog? */
2126         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
2127                 goto out;
2128 
2129         /*      This is a (useful) BSD violating of the RFC. There is a
2130          *      problem with TCP as specified in that the other end could
2131          *      keep a socket open forever with no application left this end.
2132          *      We use a 1 minute timeout (about the same as BSD) then kill
2133          *      our end. If they send after that then tough - BUT: long enough
2134          *      that we won't make the old 4*rto = almost no time - whoops
2135          *      reset mistake.
2136          *
2137          *      Nope, it was not mistake. It is really desired behaviour
2138          *      f.e. on http servers, when such sockets are useless, but
2139          *      consume significant resources. Let's do it with special
2140          *      linger2 option.                                 --ANK
2141          */
2142 
2143         if (sk->sk_state == TCP_FIN_WAIT2) {
2144                 struct tcp_sock *tp = tcp_sk(sk);
2145                 if (tp->linger2 < 0) {
2146                         tcp_set_state(sk, TCP_CLOSE);
2147                         tcp_send_active_reset(sk, GFP_ATOMIC);
2148                         NET_INC_STATS_BH(sock_net(sk),
2149                                         LINUX_MIB_TCPABORTONLINGER);
2150                 } else {
2151                         const int tmo = tcp_fin_time(sk);
2152 
2153                         if (tmo > TCP_TIMEWAIT_LEN) {
2154                                 inet_csk_reset_keepalive_timer(sk,
2155                                                 tmo - TCP_TIMEWAIT_LEN);
2156                         } else {
2157                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2158                                 goto out;
2159                         }
2160                 }
2161         }
2162         if (sk->sk_state != TCP_CLOSE) {
2163                 sk_mem_reclaim(sk);
2164                 if (tcp_check_oom(sk, 0)) {
2165                         tcp_set_state(sk, TCP_CLOSE);
2166                         tcp_send_active_reset(sk, GFP_ATOMIC);
2167                         NET_INC_STATS_BH(sock_net(sk),
2168                                         LINUX_MIB_TCPABORTONMEMORY);
2169                 }
2170         }
2171 
2172         if (sk->sk_state == TCP_CLOSE) {
2173                 struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
2174                 /* We could get here with a non-NULL req if the socket is
2175                  * aborted (e.g., closed with unread data) before 3WHS
2176                  * finishes.
2177                  */
2178                 if (req)
2179                         reqsk_fastopen_remove(sk, req, false);
2180                 inet_csk_destroy_sock(sk);
2181         }
2182         /* Otherwise, socket is reprieved until protocol close. */
2183 
2184 out:
2185         bh_unlock_sock(sk);
2186         local_bh_enable();
2187         sock_put(sk);
2188 }
2189 EXPORT_SYMBOL(tcp_close);
2190 
2191 /* These states need RST on ABORT according to RFC793 */
2192 
2193 static inline bool tcp_need_reset(int state)
2194 {
2195         return (1 << state) &
2196                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2197                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2198 }
2199 
2200 int tcp_disconnect(struct sock *sk, int flags)
2201 {
2202         struct inet_sock *inet = inet_sk(sk);
2203         struct inet_connection_sock *icsk = inet_csk(sk);
2204         struct tcp_sock *tp = tcp_sk(sk);
2205         int err = 0;
2206         int old_state = sk->sk_state;
2207 
2208         if (old_state != TCP_CLOSE)
2209                 tcp_set_state(sk, TCP_CLOSE);
2210 
2211         /* ABORT function of RFC793 */
2212         if (old_state == TCP_LISTEN) {
2213                 inet_csk_listen_stop(sk);
2214         } else if (unlikely(tp->repair)) {
2215                 sk->sk_err = ECONNABORTED;
2216         } else if (tcp_need_reset(old_state) ||
2217                    (tp->snd_nxt != tp->write_seq &&
2218                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2219                 /* The last check adjusts for discrepancy of Linux wrt. RFC
2220                  * states
2221                  */
2222                 tcp_send_active_reset(sk, gfp_any());
2223                 sk->sk_err = ECONNRESET;
2224         } else if (old_state == TCP_SYN_SENT)
2225                 sk->sk_err = ECONNRESET;
2226 
2227         tcp_clear_xmit_timers(sk);
2228         __skb_queue_purge(&sk->sk_receive_queue);
2229         tcp_write_queue_purge(sk);
2230         __skb_queue_purge(&tp->out_of_order_queue);
2231 
2232         inet->inet_dport = 0;
2233 
2234         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2235                 inet_reset_saddr(sk);
2236 
2237         sk->sk_shutdown = 0;
2238         sock_reset_flag(sk, SOCK_DONE);
2239         tp->srtt_us = 0;
2240         tp->write_seq += tp->max_window + 2;
2241         if (tp->write_seq == 0)
2242                 tp->write_seq = 1;
2243         icsk->icsk_backoff = 0;
2244         tp->snd_cwnd = 2;
2245         icsk->icsk_probes_out = 0;
2246         tp->packets_out = 0;
2247         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2248         tp->snd_cwnd_cnt = 0;
2249         tp->window_clamp = 0;
2250         tcp_set_ca_state(sk, TCP_CA_Open);
2251         tcp_clear_retrans(tp);
2252         inet_csk_delack_init(sk);
2253         tcp_init_send_head(sk);
2254         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2255         __sk_dst_reset(sk);
2256 
2257         WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
2258 
2259         sk->sk_error_report(sk);
2260         return err;
2261 }
2262 EXPORT_SYMBOL(tcp_disconnect);
2263 
2264 static inline bool tcp_can_repair_sock(const struct sock *sk)
2265 {
2266         return ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) &&
2267                 ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
2268 }
2269 
2270 static int tcp_repair_options_est(struct tcp_sock *tp,
2271                 struct tcp_repair_opt __user *optbuf, unsigned int len)
2272 {
2273         struct tcp_repair_opt opt;
2274 
2275         while (len >= sizeof(opt)) {
2276                 if (copy_from_user(&opt, optbuf, sizeof(opt)))
2277                         return -EFAULT;
2278 
2279                 optbuf++;
2280                 len -= sizeof(opt);
2281 
2282                 switch (opt.opt_code) {
2283                 case TCPOPT_MSS:
2284                         tp->rx_opt.mss_clamp = opt.opt_val;
2285                         break;
2286                 case TCPOPT_WINDOW:
2287                         {
2288                                 u16 snd_wscale = opt.opt_val & 0xFFFF;
2289                                 u16 rcv_wscale = opt.opt_val >> 16;
2290 
2291                                 if (snd_wscale > 14 || rcv_wscale > 14)
2292                                         return -EFBIG;
2293 
2294                                 tp->rx_opt.snd_wscale = snd_wscale;
2295                                 tp->rx_opt.rcv_wscale = rcv_wscale;
2296                                 tp->rx_opt.wscale_ok = 1;
2297                         }
2298                         break;
2299                 case TCPOPT_SACK_PERM:
2300                         if (opt.opt_val != 0)
2301                                 return -EINVAL;
2302 
2303                         tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
2304                         if (sysctl_tcp_fack)
2305                                 tcp_enable_fack(tp);
2306                         break;
2307                 case TCPOPT_TIMESTAMP:
2308                         if (opt.opt_val != 0)
2309                                 return -EINVAL;
2310 
2311                         tp->rx_opt.tstamp_ok = 1;
2312                         break;
2313                 }
2314         }
2315 
2316         return 0;
2317 }
2318 
2319 /*
2320  *      Socket option code for TCP.
2321  */
2322 static int do_tcp_setsockopt(struct sock *sk, int level,
2323                 int optname, char __user *optval, unsigned int optlen)
2324 {
2325         struct tcp_sock *tp = tcp_sk(sk);
2326         struct inet_connection_sock *icsk = inet_csk(sk);
2327         int val;
2328         int err = 0;
2329 
2330         /* These are data/string values, all the others are ints */
2331         switch (optname) {
2332         case TCP_CONGESTION: {
2333                 char name[TCP_CA_NAME_MAX];
2334 
2335                 if (optlen < 1)
2336                         return -EINVAL;
2337 
2338                 val = strncpy_from_user(name, optval,
2339                                         min_t(long, TCP_CA_NAME_MAX-1, optlen));
2340                 if (val < 0)
2341                         return -EFAULT;
2342                 name[val] = 0;
2343 
2344                 lock_sock(sk);
2345                 err = tcp_set_congestion_control(sk, name);
2346                 release_sock(sk);
2347                 return err;
2348         }
2349         default:
2350                 /* fallthru */
2351                 break;
2352         }
2353 
2354         if (optlen < sizeof(int))
2355                 return -EINVAL;
2356 
2357         if (get_user(val, (int __user *)optval))
2358                 return -EFAULT;
2359 
2360         lock_sock(sk);
2361 
2362         switch (optname) {
2363         case TCP_MAXSEG:
2364                 /* Values greater than interface MTU won't take effect. However
2365                  * at the point when this call is done we typically don't yet
2366                  * know which interface is going to be used */
2367                 if (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW) {
2368                         err = -EINVAL;
2369                         break;
2370                 }
2371                 tp->rx_opt.user_mss = val;
2372                 break;
2373 
2374         case TCP_NODELAY:
2375                 if (val) {
2376                         /* TCP_NODELAY is weaker than TCP_CORK, so that
2377                          * this option on corked socket is remembered, but
2378                          * it is not activated until cork is cleared.
2379                          *
2380                          * However, when TCP_NODELAY is set we make
2381                          * an explicit push, which overrides even TCP_CORK
2382                          * for currently queued segments.
2383                          */
2384                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2385                         tcp_push_pending_frames(sk);
2386                 } else {
2387                         tp->nonagle &= ~TCP_NAGLE_OFF;
2388                 }
2389                 break;
2390 
2391         case TCP_THIN_LINEAR_TIMEOUTS:
2392                 if (val < 0 || val > 1)
2393                         err = -EINVAL;
2394                 else
2395                         tp->thin_lto = val;
2396                 break;
2397 
2398         case TCP_THIN_DUPACK:
2399                 if (val < 0 || val > 1)
2400                         err = -EINVAL;
2401                 else {
2402                         tp->thin_dupack = val;
2403                         if (tp->thin_dupack)
2404                                 tcp_disable_early_retrans(tp);
2405                 }
2406                 break;
2407 
2408         case TCP_REPAIR:
2409                 if (!tcp_can_repair_sock(sk))
2410                         err = -EPERM;
2411                 else if (val == 1) {
2412                         tp->repair = 1;
2413                         sk->sk_reuse = SK_FORCE_REUSE;
2414                         tp->repair_queue = TCP_NO_QUEUE;
2415                 } else if (val == 0) {
2416                         tp->repair = 0;
2417                         sk->sk_reuse = SK_NO_REUSE;
2418                         tcp_send_window_probe(sk);
2419                 } else
2420                         err = -EINVAL;
2421 
2422                 break;
2423 
2424         case TCP_REPAIR_QUEUE:
2425                 if (!tp->repair)
2426                         err = -EPERM;
2427                 else if (val < TCP_QUEUES_NR)
2428                         tp->repair_queue = val;
2429                 else
2430                         err = -EINVAL;
2431                 break;
2432 
2433         case TCP_QUEUE_SEQ:
2434                 if (sk->sk_state != TCP_CLOSE)
2435                         err = -EPERM;
2436                 else if (tp->repair_queue == TCP_SEND_QUEUE)
2437                         tp->write_seq = val;
2438                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2439                         tp->rcv_nxt = val;
2440                 else
2441                         err = -EINVAL;
2442                 break;
2443 
2444         case TCP_REPAIR_OPTIONS:
2445                 if (!tp->repair)
2446                         err = -EINVAL;
2447                 else if (sk->sk_state == TCP_ESTABLISHED)
2448                         err = tcp_repair_options_est(tp,
2449                                         (struct tcp_repair_opt __user *)optval,
2450                                         optlen);
2451                 else
2452                         err = -EPERM;
2453                 break;
2454 
2455         case TCP_CORK:
2456                 /* When set indicates to always queue non-full frames.
2457                  * Later the user clears this option and we transmit
2458                  * any pending partial frames in the queue.  This is
2459                  * meant to be used alongside sendfile() to get properly
2460                  * filled frames when the user (for example) must write
2461                  * out headers with a write() call first and then use
2462                  * sendfile to send out the data parts.
2463                  *
2464                  * TCP_CORK can be set together with TCP_NODELAY and it is
2465                  * stronger than TCP_NODELAY.
2466                  */
2467                 if (val) {
2468                         tp->nonagle |= TCP_NAGLE_CORK;
2469                 } else {
2470                         tp->nonagle &= ~TCP_NAGLE_CORK;
2471                         if (tp->nonagle&TCP_NAGLE_OFF)
2472                                 tp->nonagle |= TCP_NAGLE_PUSH;
2473                         tcp_push_pending_frames(sk);
2474                 }
2475                 break;
2476 
2477         case TCP_KEEPIDLE:
2478                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
2479                         err = -EINVAL;
2480                 else {
2481                         tp->keepalive_time = val * HZ;
2482                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
2483                             !((1 << sk->sk_state) &
2484                               (TCPF_CLOSE | TCPF_LISTEN))) {
2485                                 u32 elapsed = keepalive_time_elapsed(tp);
2486                                 if (tp->keepalive_time > elapsed)
2487                                         elapsed = tp->keepalive_time - elapsed;
2488                                 else
2489                                         elapsed = 0;
2490                                 inet_csk_reset_keepalive_timer(sk, elapsed);
2491                         }
2492                 }
2493                 break;
2494         case TCP_KEEPINTVL:
2495                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
2496                         err = -EINVAL;
2497                 else
2498                         tp->keepalive_intvl = val * HZ;
2499                 break;
2500         case TCP_KEEPCNT:
2501                 if (val < 1 || val > MAX_TCP_KEEPCNT)
2502                         err = -EINVAL;
2503                 else
2504                         tp->keepalive_probes = val;
2505                 break;
2506         case TCP_SYNCNT:
2507                 if (val < 1 || val > MAX_TCP_SYNCNT)
2508                         err = -EINVAL;
2509                 else
2510                         icsk->icsk_syn_retries = val;
2511                 break;
2512 
2513         case TCP_SAVE_SYN:
2514                 if (val < 0 || val > 1)
2515                         err = -EINVAL;
2516                 else
2517                         tp->save_syn = val;
2518                 break;
2519 
2520         case TCP_LINGER2:
2521                 if (val < 0)
2522                         tp->linger2 = -1;
2523                 else if (val > sysctl_tcp_fin_timeout / HZ)
2524                         tp->linger2 = 0;
2525                 else
2526                         tp->linger2 = val * HZ;
2527                 break;
2528 
2529         case TCP_DEFER_ACCEPT:
2530                 /* Translate value in seconds to number of retransmits */
2531                 icsk->icsk_accept_queue.rskq_defer_accept =
2532                         secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
2533                                         TCP_RTO_MAX / HZ);
2534                 break;
2535 
2536         case TCP_WINDOW_CLAMP:
2537                 if (!val) {
2538                         if (sk->sk_state != TCP_CLOSE) {
2539                                 err = -EINVAL;
2540                                 break;
2541                         }
2542                         tp->window_clamp = 0;
2543                 } else
2544                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2545                                                 SOCK_MIN_RCVBUF / 2 : val;
2546                 break;
2547 
2548         case TCP_QUICKACK:
2549                 if (!val) {
2550                         icsk->icsk_ack.pingpong = 1;
2551                 } else {
2552                         icsk->icsk_ack.pingpong = 0;
2553                         if ((1 << sk->sk_state) &
2554                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2555                             inet_csk_ack_scheduled(sk)) {
2556                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2557                                 tcp_cleanup_rbuf(sk, 1);
2558                                 if (!(val & 1))
2559                                         icsk->icsk_ack.pingpong = 1;
2560                         }
2561                 }
2562                 break;
2563 
2564 #ifdef CONFIG_TCP_MD5SIG
2565         case TCP_MD5SIG:
2566                 /* Read the IP->Key mappings from userspace */
2567                 err = tp->af_specific->md5_parse(sk, optval, optlen);
2568                 break;
2569 #endif
2570         case TCP_USER_TIMEOUT:
2571                 /* Cap the max time in ms TCP will retry or probe the window
2572                  * before giving up and aborting (ETIMEDOUT) a connection.
2573                  */
2574                 if (val < 0)
2575                         err = -EINVAL;
2576                 else
2577                         icsk->icsk_user_timeout = msecs_to_jiffies(val);
2578                 break;
2579 
2580         case TCP_FASTOPEN:
2581                 if (val >= 0 && ((1 << sk->sk_state) & (TCPF_CLOSE |
2582                     TCPF_LISTEN))) {
2583                         tcp_fastopen_init_key_once(true);
2584 
2585                         fastopen_queue_tune(sk, val);
2586                 } else {
2587                         err = -EINVAL;
2588                 }
2589                 break;
2590         case TCP_TIMESTAMP:
2591                 if (!tp->repair)
2592                         err = -EPERM;
2593                 else
2594                         tp->tsoffset = val - tcp_time_stamp;
2595                 break;
2596         case TCP_NOTSENT_LOWAT:
2597                 tp->notsent_lowat = val;
2598                 sk->sk_write_space(sk);
2599                 break;
2600         default:
2601                 err = -ENOPROTOOPT;
2602                 break;
2603         }
2604 
2605         release_sock(sk);
2606         return err;
2607 }
2608 
2609 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2610                    unsigned int optlen)
2611 {
2612         const struct inet_connection_sock *icsk = inet_csk(sk);
2613 
2614         if (level != SOL_TCP)
2615                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2616                                                      optval, optlen);
2617         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2618 }
2619 EXPORT_SYMBOL(tcp_setsockopt);
2620 
2621 #ifdef CONFIG_COMPAT
2622 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2623                           char __user *optval, unsigned int optlen)
2624 {
2625         if (level != SOL_TCP)
2626                 return inet_csk_compat_setsockopt(sk, level, optname,
2627                                                   optval, optlen);
2628         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2629 }
2630 EXPORT_SYMBOL(compat_tcp_setsockopt);
2631 #endif
2632 
2633 /* Return information about state of tcp endpoint in API format. */
2634 void tcp_get_info(struct sock *sk, struct tcp_info *info)
2635 {
2636         const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
2637         const struct inet_connection_sock *icsk = inet_csk(sk);
2638         u32 now = tcp_time_stamp;
2639         unsigned int start;
2640         u32 rate;
2641 
2642         memset(info, 0, sizeof(*info));
2643         if (sk->sk_type != SOCK_STREAM)
2644                 return;
2645 
2646         info->tcpi_state = sk_state_load(sk);
2647 
2648         info->tcpi_ca_state = icsk->icsk_ca_state;
2649         info->tcpi_retransmits = icsk->icsk_retransmits;
2650         info->tcpi_probes = icsk->icsk_probes_out;
2651         info->tcpi_backoff = icsk->icsk_backoff;
2652 
2653         if (tp->rx_opt.tstamp_ok)
2654                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2655         if (tcp_is_sack(tp))
2656                 info->tcpi_options |= TCPI_OPT_SACK;
2657         if (tp->rx_opt.wscale_ok) {
2658                 info->tcpi_options |= TCPI_OPT_WSCALE;
2659                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2660                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2661         }
2662 
2663         if (tp->ecn_flags & TCP_ECN_OK)
2664                 info->tcpi_options |= TCPI_OPT_ECN;
2665         if (tp->ecn_flags & TCP_ECN_SEEN)
2666                 info->tcpi_options |= TCPI_OPT_ECN_SEEN;
2667         if (tp->syn_data_acked)
2668                 info->tcpi_options |= TCPI_OPT_SYN_DATA;
2669 
2670         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2671         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2672         info->tcpi_snd_mss = tp->mss_cache;
2673         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2674 
2675         if (info->tcpi_state == TCP_LISTEN) {
2676                 info->tcpi_unacked = sk->sk_ack_backlog;
2677                 info->tcpi_sacked = sk->sk_max_ack_backlog;
2678         } else {
2679                 info->tcpi_unacked = tp->packets_out;
2680                 info->tcpi_sacked = tp->sacked_out;
2681         }
2682         info->tcpi_lost = tp->lost_out;
2683         info->tcpi_retrans = tp->retrans_out;
2684         info->tcpi_fackets = tp->fackets_out;
2685 
2686         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2687         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2688         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2689 
2690         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2691         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2692         info->tcpi_rtt = tp->srtt_us >> 3;
2693         info->tcpi_rttvar = tp->mdev_us >> 2;
2694         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2695         info->tcpi_snd_cwnd = tp->snd_cwnd;
2696         info->tcpi_advmss = tp->advmss;
2697         info->tcpi_reordering = tp->reordering;
2698 
2699         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2700         info->tcpi_rcv_space = tp->rcvq_space.space;
2701 
2702         info->tcpi_total_retrans = tp->total_retrans;
2703 
2704         rate = READ_ONCE(sk->sk_pacing_rate);
2705         info->tcpi_pacing_rate = rate != ~0U ? rate : ~0ULL;
2706 
2707         rate = READ_ONCE(sk->sk_max_pacing_rate);
2708         info->tcpi_max_pacing_rate = rate != ~0U ? rate : ~0ULL;
2709 
2710         do {
2711                 start = u64_stats_fetch_begin_irq(&tp->syncp);
2712                 info->tcpi_bytes_acked = tp->bytes_acked;
2713                 info->tcpi_bytes_received = tp->bytes_received;
2714         } while (u64_stats_fetch_retry_irq(&tp->syncp, start));
2715         info->tcpi_segs_out = tp->segs_out;
2716         info->tcpi_segs_in = tp->segs_in;
2717 }
2718 EXPORT_SYMBOL_GPL(tcp_get_info);
2719 
2720 static int do_tcp_getsockopt(struct sock *sk, int level,
2721                 int optname, char __user *optval, int __user *optlen)
2722 {
2723         struct inet_connection_sock *icsk = inet_csk(sk);
2724         struct tcp_sock *tp = tcp_sk(sk);
2725         int val, len;
2726 
2727         if (get_user(len, optlen))
2728                 return -EFAULT;
2729 
2730         len = min_t(unsigned int, len, sizeof(int));
2731 
2732         if (len < 0)
2733                 return -EINVAL;
2734 
2735         switch (optname) {
2736         case TCP_MAXSEG:
2737                 val = tp->mss_cache;
2738                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2739                         val = tp->rx_opt.user_mss;
2740                 if (tp->repair)
2741                         val = tp->rx_opt.mss_clamp;
2742                 break;
2743         case TCP_NODELAY:
2744                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2745                 break;
2746         case TCP_CORK:
2747                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2748                 break;
2749         case TCP_KEEPIDLE:
2750                 val = keepalive_time_when(tp) / HZ;
2751                 break;
2752         case TCP_KEEPINTVL:
2753                 val = keepalive_intvl_when(tp) / HZ;
2754                 break;
2755         case TCP_KEEPCNT:
2756                 val = keepalive_probes(tp);
2757                 break;
2758         case TCP_SYNCNT:
2759                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2760                 break;
2761         case TCP_LINGER2:
2762                 val = tp->linger2;
2763                 if (val >= 0)
2764                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2765                 break;
2766         case TCP_DEFER_ACCEPT:
2767                 val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
2768                                       TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
2769                 break;
2770         case TCP_WINDOW_CLAMP:
2771                 val = tp->window_clamp;
2772                 break;
2773         case TCP_INFO: {
2774                 struct tcp_info info;
2775 
2776                 if (get_user(len, optlen))
2777                         return -EFAULT;
2778 
2779                 tcp_get_info(sk, &info);
2780 
2781                 len = min_t(unsigned int, len, sizeof(info));
2782                 if (put_user(len, optlen))
2783                         return -EFAULT;
2784                 if (copy_to_user(optval, &info, len))
2785                         return -EFAULT;
2786                 return 0;
2787         }
2788         case TCP_CC_INFO: {
2789                 const struct tcp_congestion_ops *ca_ops;
2790                 union tcp_cc_info info;
2791                 size_t sz = 0;
2792                 int attr;
2793 
2794                 if (get_user(len, optlen))
2795                         return -EFAULT;
2796 
2797                 ca_ops = icsk->icsk_ca_ops;
2798                 if (ca_ops && ca_ops->get_info)
2799                         sz = ca_ops->get_info(sk, ~0U, &attr, &info);
2800 
2801                 len = min_t(unsigned int, len, sz);
2802                 if (put_user(len, optlen))
2803                         return -EFAULT;
2804                 if (copy_to_user(optval, &info, len))
2805                         return -EFAULT;
2806                 return 0;
2807         }
2808         case TCP_QUICKACK:
2809                 val = !icsk->icsk_ack.pingpong;
2810                 break;
2811 
2812         case TCP_CONGESTION:
2813                 if (get_user(len, optlen))
2814                         return -EFAULT;
2815                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2816                 if (put_user(len, optlen))
2817                         return -EFAULT;
2818                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2819                         return -EFAULT;
2820                 return 0;
2821 
2822         case TCP_THIN_LINEAR_TIMEOUTS:
2823                 val = tp->thin_lto;
2824                 break;
2825         case TCP_THIN_DUPACK:
2826                 val = tp->thin_dupack;
2827                 break;
2828 
2829         case TCP_REPAIR:
2830                 val = tp->repair;
2831                 break;
2832 
2833         case TCP_REPAIR_QUEUE:
2834                 if (tp->repair)
2835                         val = tp->repair_queue;
2836                 else
2837                         return -EINVAL;
2838                 break;
2839 
2840         case TCP_QUEUE_SEQ:
2841                 if (tp->repair_queue == TCP_SEND_QUEUE)
2842                         val = tp->write_seq;
2843                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2844                         val = tp->rcv_nxt;
2845                 else
2846                         return -EINVAL;
2847                 break;
2848 
2849         case TCP_USER_TIMEOUT:
2850                 val = jiffies_to_msecs(icsk->icsk_user_timeout);
2851                 break;
2852 
2853         case TCP_FASTOPEN:
2854                 val = icsk->icsk_accept_queue.fastopenq.max_qlen;
2855                 break;
2856 
2857         case TCP_TIMESTAMP:
2858                 val = tcp_time_stamp + tp->tsoffset;
2859                 break;
2860         case TCP_NOTSENT_LOWAT:
2861                 val = tp->notsent_lowat;
2862                 break;
2863         case TCP_SAVE_SYN:
2864                 val = tp->save_syn;
2865                 break;
2866         case TCP_SAVED_SYN: {
2867                 if (get_user(len, optlen))
2868                         return -EFAULT;
2869 
2870                 lock_sock(sk);
2871                 if (tp->saved_syn) {
2872                         if (len < tp->saved_syn[0]) {
2873                                 if (put_user(tp->saved_syn[0], optlen)) {
2874                                         release_sock(sk);
2875                                         return -EFAULT;
2876                                 }
2877                                 release_sock(sk);
2878                                 return -EINVAL;
2879                         }
2880                         len = tp->saved_syn[0];
2881                         if (put_user(len, optlen)) {
2882                                 release_sock(sk);
2883                                 return -EFAULT;
2884                         }
2885                         if (copy_to_user(optval, tp->saved_syn + 1, len)) {
2886                                 release_sock(sk);
2887                                 return -EFAULT;
2888                         }
2889                         tcp_saved_syn_free(tp);
2890                         release_sock(sk);
2891                 } else {
2892                         release_sock(sk);
2893                         len = 0;
2894                         if (put_user(len, optlen))
2895                                 return -EFAULT;
2896                 }
2897                 return 0;
2898         }
2899         default:
2900                 return -ENOPROTOOPT;
2901         }
2902 
2903         if (put_user(len, optlen))
2904                 return -EFAULT;
2905         if (copy_to_user(optval, &val, len))
2906                 return -EFAULT;
2907         return 0;
2908 }
2909 
2910 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2911                    int __user *optlen)
2912 {
2913         struct inet_connection_sock *icsk = inet_csk(sk);
2914 
2915         if (level != SOL_TCP)
2916                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2917                                                      optval, optlen);
2918         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2919 }
2920 EXPORT_SYMBOL(tcp_getsockopt);
2921 
2922 #ifdef CONFIG_COMPAT
2923 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2924                           char __user *optval, int __user *optlen)
2925 {
2926         if (level != SOL_TCP)
2927                 return inet_csk_compat_getsockopt(sk, level, optname,
2928                                                   optval, optlen);
2929         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2930 }
2931 EXPORT_SYMBOL(compat_tcp_getsockopt);
2932 #endif
2933 
2934 #ifdef CONFIG_TCP_MD5SIG
2935 static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool);
2936 static DEFINE_MUTEX(tcp_md5sig_mutex);
2937 static bool tcp_md5sig_pool_populated = false;
2938 
2939 static void __tcp_alloc_md5sig_pool(void)
2940 {
2941         int cpu;
2942 
2943         for_each_possible_cpu(cpu) {
2944                 if (!per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm) {
2945                         struct crypto_hash *hash;
2946 
2947                         hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2948                         if (IS_ERR_OR_NULL(hash))
2949                                 return;
2950                         per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm = hash;
2951                 }
2952         }
2953         /* before setting tcp_md5sig_pool_populated, we must commit all writes
2954          * to memory. See smp_rmb() in tcp_get_md5sig_pool()
2955          */
2956         smp_wmb();
2957         tcp_md5sig_pool_populated = true;
2958 }
2959 
2960 bool tcp_alloc_md5sig_pool(void)
2961 {
2962         if (unlikely(!tcp_md5sig_pool_populated)) {
2963                 mutex_lock(&tcp_md5sig_mutex);
2964 
2965                 if (!tcp_md5sig_pool_populated)
2966                         __tcp_alloc_md5sig_pool();
2967 
2968                 mutex_unlock(&tcp_md5sig_mutex);
2969         }
2970         return tcp_md5sig_pool_populated;
2971 }
2972 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2973 
2974 
2975 /**
2976  *      tcp_get_md5sig_pool - get md5sig_pool for this user
2977  *
2978  *      We use percpu structure, so if we succeed, we exit with preemption
2979  *      and BH disabled, to make sure another thread or softirq handling
2980  *      wont try to get same context.
2981  */
2982 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
2983 {
2984         local_bh_disable();
2985 
2986         if (tcp_md5sig_pool_populated) {
2987                 /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
2988                 smp_rmb();
2989                 return this_cpu_ptr(&tcp_md5sig_pool);
2990         }
2991         local_bh_enable();
2992         return NULL;
2993 }
2994 EXPORT_SYMBOL(tcp_get_md5sig_pool);
2995 
2996 int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
2997                         const struct tcphdr *th)
2998 {
2999         struct scatterlist sg;
3000         struct tcphdr hdr;
3001         int err;
3002 
3003         /* We are not allowed to change tcphdr, make a local copy */
3004         memcpy(&hdr, th, sizeof(hdr));
3005         hdr.check = 0;
3006 
3007         /* options aren't included in the hash */
3008         sg_init_one(&sg, &hdr, sizeof(hdr));
3009         err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(hdr));
3010         return err;
3011 }
3012 EXPORT_SYMBOL(tcp_md5_hash_header);
3013 
3014 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
3015                           const struct sk_buff *skb, unsigned int header_len)
3016 {
3017         struct scatterlist sg;
3018         const struct tcphdr *tp = tcp_hdr(skb);
3019         struct hash_desc *desc = &hp->md5_desc;
3020         unsigned int i;
3021         const unsigned int head_data_len = skb_headlen(skb) > header_len ?
3022                                            skb_headlen(skb) - header_len : 0;
3023         const struct skb_shared_info *shi = skb_shinfo(skb);
3024         struct sk_buff *frag_iter;
3025 
3026         sg_init_table(&sg, 1);
3027 
3028         sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
3029         if (crypto_hash_update(desc, &sg, head_data_len))
3030                 return 1;
3031 
3032         for (i = 0; i < shi->nr_frags; ++i) {
3033                 const struct skb_frag_struct *f = &shi->frags[i];
3034                 unsigned int offset = f->page_offset;
3035                 struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
3036 
3037                 sg_set_page(&sg, page, skb_frag_size(f),
3038                             offset_in_page(offset));
3039                 if (crypto_hash_update(desc, &sg, skb_frag_size(f)))
3040                         return 1;
3041         }
3042 
3043         skb_walk_frags(skb, frag_iter)
3044                 if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
3045                         return 1;
3046 
3047         return 0;
3048 }
3049 EXPORT_SYMBOL(tcp_md5_hash_skb_data);
3050 
3051 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key)
3052 {
3053         struct scatterlist sg;
3054 
3055         sg_init_one(&sg, key->key, key->keylen);
3056         return crypto_hash_update(&hp->md5_desc, &sg, key->keylen);
3057 }
3058 EXPORT_SYMBOL(tcp_md5_hash_key);
3059 
3060 #endif
3061 
3062 void tcp_done(struct sock *sk)
3063 {
3064         struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
3065 
3066         if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
3067                 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
3068 
3069         tcp_set_state(sk, TCP_CLOSE);
3070         tcp_clear_xmit_timers(sk);
3071         if (req)
3072                 reqsk_fastopen_remove(sk, req, false);
3073 
3074         sk->sk_shutdown = SHUTDOWN_MASK;
3075 
3076         if (!sock_flag(sk, SOCK_DEAD))
3077                 sk->sk_state_change(sk);
3078         else
3079                 inet_csk_destroy_sock(sk);
3080 }
3081 EXPORT_SYMBOL_GPL(tcp_done);
3082 
3083 extern struct tcp_congestion_ops tcp_reno;
3084 
3085 static __initdata unsigned long thash_entries;
3086 static int __init set_thash_entries(char *str)
3087 {
3088         ssize_t ret;
3089 
3090         if (!str)
3091                 return 0;
3092 
3093         ret = kstrtoul(str, 0, &thash_entries);
3094         if (ret)
3095                 return 0;
3096 
3097         return 1;
3098 }
3099 __setup("thash_entries=", set_thash_entries);
3100 
3101 static void __init tcp_init_mem(void)
3102 {
3103         unsigned long limit = nr_free_buffer_pages() / 16;
3104 
3105         limit = max(limit, 128UL);
3106         sysctl_tcp_mem[0] = limit / 4 * 3;              /* 4.68 % */
3107         sysctl_tcp_mem[1] = limit;                      /* 6.25 % */
3108         sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;      /* 9.37 % */
3109 }
3110 
3111 void __init tcp_init(void)
3112 {
3113         unsigned long limit;
3114         int max_rshare, max_wshare, cnt;
3115         unsigned int i;
3116 
3117         sock_skb_cb_check_size(sizeof(struct tcp_skb_cb));
3118 
3119         percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
3120         percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL);
3121         tcp_hashinfo.bind_bucket_cachep =
3122                 kmem_cache_create("tcp_bind_bucket",
3123                                   sizeof(struct inet_bind_bucket), 0,
3124                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3125 
3126         /* Size and allocate the main established and bind bucket
3127          * hash tables.
3128          *
3129          * The methodology is similar to that of the buffer cache.
3130          */
3131         tcp_hashinfo.ehash =
3132                 alloc_large_system_hash("TCP established",
3133                                         sizeof(struct inet_ehash_bucket),
3134                                         thash_entries,
3135                                         17, /* one slot per 128 KB of memory */
3136                                         0,
3137                                         NULL,
3138                                         &tcp_hashinfo.ehash_mask,
3139                                         0,
3140                                         thash_entries ? 0 : 512 * 1024);
3141         for (i = 0; i <= tcp_hashinfo.ehash_mask; i++)
3142                 INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
3143 
3144         if (inet_ehash_locks_alloc(&tcp_hashinfo))
3145                 panic("TCP: failed to alloc ehash_locks");
3146         tcp_hashinfo.bhash =
3147                 alloc_large_system_hash("TCP bind",
3148                                         sizeof(struct inet_bind_hashbucket),
3149                                         tcp_hashinfo.ehash_mask + 1,
3150                                         17, /* one slot per 128 KB of memory */
3151                                         0,
3152                                         &tcp_hashinfo.bhash_size,
3153                                         NULL,
3154                                         0,
3155                                         64 * 1024);
3156         tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
3157         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
3158                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
3159                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
3160         }
3161 
3162 
3163         cnt = tcp_hashinfo.ehash_mask + 1;
3164 
3165         tcp_death_row.sysctl_max_tw_buckets = cnt / 2;
3166         sysctl_tcp_max_orphans = cnt / 2;
3167         sysctl_max_syn_backlog = max(128, cnt / 256);
3168 
3169         tcp_init_mem();
3170         /* Set per-socket limits to no more than 1/128 the pressure threshold */
3171         limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
3172         max_wshare = min(4UL*1024*1024, limit);
3173         max_rshare = min(6UL*1024*1024, limit);
3174 
3175         sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
3176         sysctl_tcp_wmem[1] = 16*1024;
3177         sysctl_tcp_wmem[2] = max(64*1024, max_wshare);
3178 
3179         sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
3180         sysctl_tcp_rmem[1] = 87380;
3181         sysctl_tcp_rmem[2] = max(87380, max_rshare);
3182 
3183         pr_info("Hash tables configured (established %u bind %u)\n",
3184                 tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
3185 
3186         tcp_metrics_init();
3187         BUG_ON(tcp_register_congestion_control(&tcp_reno) != 0);
3188         tcp_tasklet_init();
3189 }
3190 

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