Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18

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

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