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Linux/net/ipv4/tcp.c

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

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