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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 <crypto/hash.h>
251 #include <linux/kernel.h>
252 #include <linux/module.h>
253 #include <linux/types.h>
254 #include <linux/fcntl.h>
255 #include <linux/poll.h>
256 #include <linux/inet_diag.h>
257 #include <linux/init.h>
258 #include <linux/fs.h>
259 #include <linux/skbuff.h>
260 #include <linux/scatterlist.h>
261 #include <linux/splice.h>
262 #include <linux/net.h>
263 #include <linux/socket.h>
264 #include <linux/random.h>
265 #include <linux/bootmem.h>
266 #include <linux/highmem.h>
267 #include <linux/swap.h>
268 #include <linux/cache.h>
269 #include <linux/err.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 <asm/unaligned.h>
283 #include <net/busy_poll.h>
284 
285 int sysctl_tcp_min_tso_segs __read_mostly = 2;
286 
287 int sysctl_tcp_autocorking __read_mostly = 1;
288 
289 struct percpu_counter tcp_orphan_count;
290 EXPORT_SYMBOL_GPL(tcp_orphan_count);
291 
292 long sysctl_tcp_mem[3] __read_mostly;
293 int sysctl_tcp_wmem[3] __read_mostly;
294 int sysctl_tcp_rmem[3] __read_mostly;
295 
296 EXPORT_SYMBOL(sysctl_tcp_mem);
297 EXPORT_SYMBOL(sysctl_tcp_rmem);
298 EXPORT_SYMBOL(sysctl_tcp_wmem);
299 
300 atomic_long_t tcp_memory_allocated;     /* Current allocated memory. */
301 EXPORT_SYMBOL(tcp_memory_allocated);
302 
303 /*
304  * Current number of TCP sockets.
305  */
306 struct percpu_counter tcp_sockets_allocated;
307 EXPORT_SYMBOL(tcp_sockets_allocated);
308 
309 /*
310  * TCP splice context
311  */
312 struct tcp_splice_state {
313         struct pipe_inode_info *pipe;
314         size_t len;
315         unsigned int flags;
316 };
317 
318 /*
319  * Pressure flag: try to collapse.
320  * Technical note: it is used by multiple contexts non atomically.
321  * All the __sk_mem_schedule() is of this nature: accounting
322  * is strict, actions are advisory and have some latency.
323  */
324 int tcp_memory_pressure __read_mostly;
325 EXPORT_SYMBOL(tcp_memory_pressure);
326 
327 void tcp_enter_memory_pressure(struct sock *sk)
328 {
329         if (!tcp_memory_pressure) {
330                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
331                 tcp_memory_pressure = 1;
332         }
333 }
334 EXPORT_SYMBOL(tcp_enter_memory_pressure);
335 
336 /* Convert seconds to retransmits based on initial and max timeout */
337 static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
338 {
339         u8 res = 0;
340 
341         if (seconds > 0) {
342                 int period = timeout;
343 
344                 res = 1;
345                 while (seconds > period && res < 255) {
346                         res++;
347                         timeout <<= 1;
348                         if (timeout > rto_max)
349                                 timeout = rto_max;
350                         period += timeout;
351                 }
352         }
353         return res;
354 }
355 
356 /* Convert retransmits to seconds based on initial and max timeout */
357 static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
358 {
359         int period = 0;
360 
361         if (retrans > 0) {
362                 period = timeout;
363                 while (--retrans) {
364                         timeout <<= 1;
365                         if (timeout > rto_max)
366                                 timeout = rto_max;
367                         period += timeout;
368                 }
369         }
370         return period;
371 }
372 
373 /* Address-family independent initialization for a tcp_sock.
374  *
375  * NOTE: A lot of things set to zero explicitly by call to
376  *       sk_alloc() so need not be done here.
377  */
378 void tcp_init_sock(struct sock *sk)
379 {
380         struct inet_connection_sock *icsk = inet_csk(sk);
381         struct tcp_sock *tp = tcp_sk(sk);
382 
383         __skb_queue_head_init(&tp->out_of_order_queue);
384         tcp_init_xmit_timers(sk);
385         tcp_prequeue_init(tp);
386         INIT_LIST_HEAD(&tp->tsq_node);
387 
388         icsk->icsk_rto = TCP_TIMEOUT_INIT;
389         tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
390         tp->rtt_min[0].rtt = ~0U;
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 = sock_net(sk)->ipv4.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         if (mem_cgroup_sockets_enabled)
425                 sock_update_memcg(sk);
426         sk_sockets_allocated_inc(sk);
427         local_bh_enable();
428 }
429 EXPORT_SYMBOL(tcp_init_sock);
430 
431 static void tcp_tx_timestamp(struct sock *sk, u16 tsflags, struct sk_buff *skb)
432 {
433         if (tsflags) {
434                 struct skb_shared_info *shinfo = skb_shinfo(skb);
435                 struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
436 
437                 sock_tx_timestamp(sk, tsflags, &shinfo->tx_flags);
438                 if (tsflags & SOF_TIMESTAMPING_TX_ACK)
439                         tcb->txstamp_ack = 1;
440                 if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
441                         shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
442         }
443 }
444 
445 /*
446  *      Wait for a TCP event.
447  *
448  *      Note that we don't need to lock the socket, as the upper poll layers
449  *      take care of normal races (between the test and the event) and we don't
450  *      go look at any of the socket buffers directly.
451  */
452 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
453 {
454         unsigned int mask;
455         struct sock *sk = sock->sk;
456         const struct tcp_sock *tp = tcp_sk(sk);
457         int state;
458 
459         sock_rps_record_flow(sk);
460 
461         sock_poll_wait(file, sk_sleep(sk), wait);
462 
463         state = sk_state_load(sk);
464         if (state == TCP_LISTEN)
465                 return inet_csk_listen_poll(sk);
466 
467         /* Socket is not locked. We are protected from async events
468          * by poll logic and correct handling of state changes
469          * made by other threads is impossible in any case.
470          */
471 
472         mask = 0;
473 
474         /*
475          * POLLHUP is certainly not done right. But poll() doesn't
476          * have a notion of HUP in just one direction, and for a
477          * socket the read side is more interesting.
478          *
479          * Some poll() documentation says that POLLHUP is incompatible
480          * with the POLLOUT/POLLWR flags, so somebody should check this
481          * all. But careful, it tends to be safer to return too many
482          * bits than too few, and you can easily break real applications
483          * if you don't tell them that something has hung up!
484          *
485          * Check-me.
486          *
487          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
488          * our fs/select.c). It means that after we received EOF,
489          * poll always returns immediately, making impossible poll() on write()
490          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
491          * if and only if shutdown has been made in both directions.
492          * Actually, it is interesting to look how Solaris and DUX
493          * solve this dilemma. I would prefer, if POLLHUP were maskable,
494          * then we could set it on SND_SHUTDOWN. BTW examples given
495          * in Stevens' books assume exactly this behaviour, it explains
496          * why POLLHUP is incompatible with POLLOUT.    --ANK
497          *
498          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
499          * blocking on fresh not-connected or disconnected socket. --ANK
500          */
501         if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
502                 mask |= POLLHUP;
503         if (sk->sk_shutdown & RCV_SHUTDOWN)
504                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
505 
506         /* Connected or passive Fast Open socket? */
507         if (state != TCP_SYN_SENT &&
508             (state != TCP_SYN_RECV || tp->fastopen_rsk)) {
509                 int target = sock_rcvlowat(sk, 0, INT_MAX);
510 
511                 if (tp->urg_seq == tp->copied_seq &&
512                     !sock_flag(sk, SOCK_URGINLINE) &&
513                     tp->urg_data)
514                         target++;
515 
516                 if (tp->rcv_nxt - tp->copied_seq >= target)
517                         mask |= POLLIN | POLLRDNORM;
518 
519                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
520                         if (sk_stream_is_writeable(sk)) {
521                                 mask |= POLLOUT | POLLWRNORM;
522                         } else {  /* send SIGIO later */
523                                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
524                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
525 
526                                 /* Race breaker. If space is freed after
527                                  * wspace test but before the flags are set,
528                                  * IO signal will be lost. Memory barrier
529                                  * pairs with the input side.
530                                  */
531                                 smp_mb__after_atomic();
532                                 if (sk_stream_is_writeable(sk))
533                                         mask |= POLLOUT | POLLWRNORM;
534                         }
535                 } else
536                         mask |= POLLOUT | POLLWRNORM;
537 
538                 if (tp->urg_data & TCP_URG_VALID)
539                         mask |= POLLPRI;
540         }
541         /* This barrier is coupled with smp_wmb() in tcp_reset() */
542         smp_rmb();
543         if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
544                 mask |= POLLERR;
545 
546         return mask;
547 }
548 EXPORT_SYMBOL(tcp_poll);
549 
550 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
551 {
552         struct tcp_sock *tp = tcp_sk(sk);
553         int answ;
554         bool slow;
555 
556         switch (cmd) {
557         case SIOCINQ:
558                 if (sk->sk_state == TCP_LISTEN)
559                         return -EINVAL;
560 
561                 slow = lock_sock_fast(sk);
562                 answ = tcp_inq(sk);
563                 unlock_sock_fast(sk, slow);
564                 break;
565         case SIOCATMARK:
566                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
567                 break;
568         case SIOCOUTQ:
569                 if (sk->sk_state == TCP_LISTEN)
570                         return -EINVAL;
571 
572                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
573                         answ = 0;
574                 else
575                         answ = tp->write_seq - tp->snd_una;
576                 break;
577         case SIOCOUTQNSD:
578                 if (sk->sk_state == TCP_LISTEN)
579                         return -EINVAL;
580 
581                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
582                         answ = 0;
583                 else
584                         answ = tp->write_seq - tp->snd_nxt;
585                 break;
586         default:
587                 return -ENOIOCTLCMD;
588         }
589 
590         return put_user(answ, (int __user *)arg);
591 }
592 EXPORT_SYMBOL(tcp_ioctl);
593 
594 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
595 {
596         TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
597         tp->pushed_seq = tp->write_seq;
598 }
599 
600 static inline bool forced_push(const struct tcp_sock *tp)
601 {
602         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
603 }
604 
605 static void skb_entail(struct sock *sk, struct sk_buff *skb)
606 {
607         struct tcp_sock *tp = tcp_sk(sk);
608         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
609 
610         skb->csum    = 0;
611         tcb->seq     = tcb->end_seq = tp->write_seq;
612         tcb->tcp_flags = TCPHDR_ACK;
613         tcb->sacked  = 0;
614         __skb_header_release(skb);
615         tcp_add_write_queue_tail(sk, skb);
616         sk->sk_wmem_queued += skb->truesize;
617         sk_mem_charge(sk, skb->truesize);
618         if (tp->nonagle & TCP_NAGLE_PUSH)
619                 tp->nonagle &= ~TCP_NAGLE_PUSH;
620 
621         tcp_slow_start_after_idle_check(sk);
622 }
623 
624 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
625 {
626         if (flags & MSG_OOB)
627                 tp->snd_up = tp->write_seq;
628 }
629 
630 /* If a not yet filled skb is pushed, do not send it if
631  * we have data packets in Qdisc or NIC queues :
632  * Because TX completion will happen shortly, it gives a chance
633  * to coalesce future sendmsg() payload into this skb, without
634  * need for a timer, and with no latency trade off.
635  * As packets containing data payload have a bigger truesize
636  * than pure acks (dataless) packets, the last checks prevent
637  * autocorking if we only have an ACK in Qdisc/NIC queues,
638  * or if TX completion was delayed after we processed ACK packet.
639  */
640 static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
641                                 int size_goal)
642 {
643         return skb->len < size_goal &&
644                sysctl_tcp_autocorking &&
645                skb != tcp_write_queue_head(sk) &&
646                atomic_read(&sk->sk_wmem_alloc) > skb->truesize;
647 }
648 
649 static void tcp_push(struct sock *sk, int flags, int mss_now,
650                      int nonagle, int size_goal)
651 {
652         struct tcp_sock *tp = tcp_sk(sk);
653         struct sk_buff *skb;
654 
655         if (!tcp_send_head(sk))
656                 return;
657 
658         skb = tcp_write_queue_tail(sk);
659         if (!(flags & MSG_MORE) || forced_push(tp))
660                 tcp_mark_push(tp, skb);
661 
662         tcp_mark_urg(tp, flags);
663 
664         if (tcp_should_autocork(sk, skb, size_goal)) {
665 
666                 /* avoid atomic op if TSQ_THROTTLED bit is already set */
667                 if (!test_bit(TSQ_THROTTLED, &tp->tsq_flags)) {
668                         NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTOCORKING);
669                         set_bit(TSQ_THROTTLED, &tp->tsq_flags);
670                 }
671                 /* It is possible TX completion already happened
672                  * before we set TSQ_THROTTLED.
673                  */
674                 if (atomic_read(&sk->sk_wmem_alloc) > skb->truesize)
675                         return;
676         }
677 
678         if (flags & MSG_MORE)
679                 nonagle = TCP_NAGLE_CORK;
680 
681         __tcp_push_pending_frames(sk, mss_now, nonagle);
682 }
683 
684 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
685                                 unsigned int offset, size_t len)
686 {
687         struct tcp_splice_state *tss = rd_desc->arg.data;
688         int ret;
689 
690         ret = skb_splice_bits(skb, skb->sk, offset, tss->pipe,
691                               min(rd_desc->count, len), tss->flags,
692                               skb_socket_splice);
693         if (ret > 0)
694                 rd_desc->count -= ret;
695         return ret;
696 }
697 
698 static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
699 {
700         /* Store TCP splice context information in read_descriptor_t. */
701         read_descriptor_t rd_desc = {
702                 .arg.data = tss,
703                 .count    = tss->len,
704         };
705 
706         return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
707 }
708 
709 /**
710  *  tcp_splice_read - splice data from TCP socket to a pipe
711  * @sock:       socket to splice from
712  * @ppos:       position (not valid)
713  * @pipe:       pipe to splice to
714  * @len:        number of bytes to splice
715  * @flags:      splice modifier flags
716  *
717  * Description:
718  *    Will read pages from given socket and fill them into a pipe.
719  *
720  **/
721 ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
722                         struct pipe_inode_info *pipe, size_t len,
723                         unsigned int flags)
724 {
725         struct sock *sk = sock->sk;
726         struct tcp_splice_state tss = {
727                 .pipe = pipe,
728                 .len = len,
729                 .flags = flags,
730         };
731         long timeo;
732         ssize_t spliced;
733         int ret;
734 
735         sock_rps_record_flow(sk);
736         /*
737          * We can't seek on a socket input
738          */
739         if (unlikely(*ppos))
740                 return -ESPIPE;
741 
742         ret = spliced = 0;
743 
744         lock_sock(sk);
745 
746         timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
747         while (tss.len) {
748                 ret = __tcp_splice_read(sk, &tss);
749                 if (ret < 0)
750                         break;
751                 else if (!ret) {
752                         if (spliced)
753                                 break;
754                         if (sock_flag(sk, SOCK_DONE))
755                                 break;
756                         if (sk->sk_err) {
757                                 ret = sock_error(sk);
758                                 break;
759                         }
760                         if (sk->sk_shutdown & RCV_SHUTDOWN)
761                                 break;
762                         if (sk->sk_state == TCP_CLOSE) {
763                                 /*
764                                  * This occurs when user tries to read
765                                  * from never connected socket.
766                                  */
767                                 if (!sock_flag(sk, SOCK_DONE))
768                                         ret = -ENOTCONN;
769                                 break;
770                         }
771                         if (!timeo) {
772                                 ret = -EAGAIN;
773                                 break;
774                         }
775                         sk_wait_data(sk, &timeo, NULL);
776                         if (signal_pending(current)) {
777                                 ret = sock_intr_errno(timeo);
778                                 break;
779                         }
780                         continue;
781                 }
782                 tss.len -= ret;
783                 spliced += ret;
784 
785                 if (!timeo)
786                         break;
787                 release_sock(sk);
788                 lock_sock(sk);
789 
790                 if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
791                     (sk->sk_shutdown & RCV_SHUTDOWN) ||
792                     signal_pending(current))
793                         break;
794         }
795 
796         release_sock(sk);
797 
798         if (spliced)
799                 return spliced;
800 
801         return ret;
802 }
803 EXPORT_SYMBOL(tcp_splice_read);
804 
805 struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
806                                     bool force_schedule)
807 {
808         struct sk_buff *skb;
809 
810         /* The TCP header must be at least 32-bit aligned.  */
811         size = ALIGN(size, 4);
812 
813         if (unlikely(tcp_under_memory_pressure(sk)))
814                 sk_mem_reclaim_partial(sk);
815 
816         skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
817         if (likely(skb)) {
818                 bool mem_scheduled;
819 
820                 if (force_schedule) {
821                         mem_scheduled = true;
822                         sk_forced_mem_schedule(sk, skb->truesize);
823                 } else {
824                         mem_scheduled = sk_wmem_schedule(sk, skb->truesize);
825                 }
826                 if (likely(mem_scheduled)) {
827                         skb_reserve(skb, sk->sk_prot->max_header);
828                         /*
829                          * Make sure that we have exactly size bytes
830                          * available to the caller, no more, no less.
831                          */
832                         skb->reserved_tailroom = skb->end - skb->tail - size;
833                         return skb;
834                 }
835                 __kfree_skb(skb);
836         } else {
837                 sk->sk_prot->enter_memory_pressure(sk);
838                 sk_stream_moderate_sndbuf(sk);
839         }
840         return NULL;
841 }
842 
843 static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
844                                        int large_allowed)
845 {
846         struct tcp_sock *tp = tcp_sk(sk);
847         u32 new_size_goal, size_goal;
848 
849         if (!large_allowed || !sk_can_gso(sk))
850                 return mss_now;
851 
852         /* Note : tcp_tso_autosize() will eventually split this later */
853         new_size_goal = sk->sk_gso_max_size - 1 - MAX_TCP_HEADER;
854         new_size_goal = tcp_bound_to_half_wnd(tp, new_size_goal);
855 
856         /* We try hard to avoid divides here */
857         size_goal = tp->gso_segs * mss_now;
858         if (unlikely(new_size_goal < size_goal ||
859                      new_size_goal >= size_goal + mss_now)) {
860                 tp->gso_segs = min_t(u16, new_size_goal / mss_now,
861                                      sk->sk_gso_max_segs);
862                 size_goal = tp->gso_segs * mss_now;
863         }
864 
865         return max(size_goal, mss_now);
866 }
867 
868 static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
869 {
870         int mss_now;
871 
872         mss_now = tcp_current_mss(sk);
873         *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
874 
875         return mss_now;
876 }
877 
878 static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
879                                 size_t size, int flags)
880 {
881         struct tcp_sock *tp = tcp_sk(sk);
882         int mss_now, size_goal;
883         int err;
884         ssize_t copied;
885         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
886 
887         /* Wait for a connection to finish. One exception is TCP Fast Open
888          * (passive side) where data is allowed to be sent before a connection
889          * is fully established.
890          */
891         if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
892             !tcp_passive_fastopen(sk)) {
893                 err = sk_stream_wait_connect(sk, &timeo);
894                 if (err != 0)
895                         goto out_err;
896         }
897 
898         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
899 
900         mss_now = tcp_send_mss(sk, &size_goal, flags);
901         copied = 0;
902 
903         err = -EPIPE;
904         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
905                 goto out_err;
906 
907         while (size > 0) {
908                 struct sk_buff *skb = tcp_write_queue_tail(sk);
909                 int copy, i;
910                 bool can_coalesce;
911 
912                 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0 ||
913                     !tcp_skb_can_collapse_to(skb)) {
914 new_segment:
915                         if (!sk_stream_memory_free(sk))
916                                 goto wait_for_sndbuf;
917 
918                         skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation,
919                                                   skb_queue_empty(&sk->sk_write_queue));
920                         if (!skb)
921                                 goto wait_for_memory;
922 
923                         skb_entail(sk, skb);
924                         copy = size_goal;
925                 }
926 
927                 if (copy > size)
928                         copy = size;
929 
930                 i = skb_shinfo(skb)->nr_frags;
931                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
932                 if (!can_coalesce && i >= sysctl_max_skb_frags) {
933                         tcp_mark_push(tp, skb);
934                         goto new_segment;
935                 }
936                 if (!sk_wmem_schedule(sk, copy))
937                         goto wait_for_memory;
938 
939                 if (can_coalesce) {
940                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
941                 } else {
942                         get_page(page);
943                         skb_fill_page_desc(skb, i, page, offset, copy);
944                 }
945                 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
946 
947                 skb->len += copy;
948                 skb->data_len += copy;
949                 skb->truesize += copy;
950                 sk->sk_wmem_queued += copy;
951                 sk_mem_charge(sk, copy);
952                 skb->ip_summed = CHECKSUM_PARTIAL;
953                 tp->write_seq += copy;
954                 TCP_SKB_CB(skb)->end_seq += copy;
955                 tcp_skb_pcount_set(skb, 0);
956 
957                 if (!copied)
958                         TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
959 
960                 copied += copy;
961                 offset += copy;
962                 size -= copy;
963                 if (!size) {
964                         tcp_tx_timestamp(sk, sk->sk_tsflags, skb);
965                         goto out;
966                 }
967 
968                 if (skb->len < size_goal || (flags & MSG_OOB))
969                         continue;
970 
971                 if (forced_push(tp)) {
972                         tcp_mark_push(tp, skb);
973                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
974                 } else if (skb == tcp_send_head(sk))
975                         tcp_push_one(sk, mss_now);
976                 continue;
977 
978 wait_for_sndbuf:
979                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
980 wait_for_memory:
981                 tcp_push(sk, flags & ~MSG_MORE, mss_now,
982                          TCP_NAGLE_PUSH, size_goal);
983 
984                 err = sk_stream_wait_memory(sk, &timeo);
985                 if (err != 0)
986                         goto do_error;
987 
988                 mss_now = tcp_send_mss(sk, &size_goal, flags);
989         }
990 
991 out:
992         if (copied && !(flags & MSG_SENDPAGE_NOTLAST))
993                 tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
994         return copied;
995 
996 do_error:
997         if (copied)
998                 goto out;
999 out_err:
1000         /* make sure we wake any epoll edge trigger waiter */
1001         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1002                 sk->sk_write_space(sk);
1003         return sk_stream_error(sk, flags, err);
1004 }
1005 
1006 int tcp_sendpage(struct sock *sk, struct page *page, int offset,
1007                  size_t size, int flags)
1008 {
1009         ssize_t res;
1010 
1011         if (!(sk->sk_route_caps & NETIF_F_SG) ||
1012             !sk_check_csum_caps(sk))
1013                 return sock_no_sendpage(sk->sk_socket, page, offset, size,
1014                                         flags);
1015 
1016         lock_sock(sk);
1017         res = do_tcp_sendpages(sk, page, offset, size, flags);
1018         release_sock(sk);
1019         return res;
1020 }
1021 EXPORT_SYMBOL(tcp_sendpage);
1022 
1023 static inline int select_size(const struct sock *sk, bool sg)
1024 {
1025         const struct tcp_sock *tp = tcp_sk(sk);
1026         int tmp = tp->mss_cache;
1027 
1028         if (sg) {
1029                 if (sk_can_gso(sk)) {
1030                         /* Small frames wont use a full page:
1031                          * Payload will immediately follow tcp header.
1032                          */
1033                         tmp = SKB_WITH_OVERHEAD(2048 - MAX_TCP_HEADER);
1034                 } else {
1035                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
1036 
1037                         if (tmp >= pgbreak &&
1038                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
1039                                 tmp = pgbreak;
1040                 }
1041         }
1042 
1043         return tmp;
1044 }
1045 
1046 void tcp_free_fastopen_req(struct tcp_sock *tp)
1047 {
1048         if (tp->fastopen_req) {
1049                 kfree(tp->fastopen_req);
1050                 tp->fastopen_req = NULL;
1051         }
1052 }
1053 
1054 static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
1055                                 int *copied, size_t size)
1056 {
1057         struct tcp_sock *tp = tcp_sk(sk);
1058         int err, flags;
1059 
1060         if (!(sysctl_tcp_fastopen & TFO_CLIENT_ENABLE))
1061                 return -EOPNOTSUPP;
1062         if (tp->fastopen_req)
1063                 return -EALREADY; /* Another Fast Open is in progress */
1064 
1065         tp->fastopen_req = kzalloc(sizeof(struct tcp_fastopen_request),
1066                                    sk->sk_allocation);
1067         if (unlikely(!tp->fastopen_req))
1068                 return -ENOBUFS;
1069         tp->fastopen_req->data = msg;
1070         tp->fastopen_req->size = size;
1071 
1072         flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
1073         err = __inet_stream_connect(sk->sk_socket, msg->msg_name,
1074                                     msg->msg_namelen, flags);
1075         *copied = tp->fastopen_req->copied;
1076         tcp_free_fastopen_req(tp);
1077         return err;
1078 }
1079 
1080 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
1081 {
1082         struct tcp_sock *tp = tcp_sk(sk);
1083         struct sk_buff *skb;
1084         struct sockcm_cookie sockc;
1085         int flags, err, copied = 0;
1086         int mss_now = 0, size_goal, copied_syn = 0;
1087         bool process_backlog = false;
1088         bool sg;
1089         long timeo;
1090 
1091         lock_sock(sk);
1092 
1093         flags = msg->msg_flags;
1094         if (flags & MSG_FASTOPEN) {
1095                 err = tcp_sendmsg_fastopen(sk, msg, &copied_syn, size);
1096                 if (err == -EINPROGRESS && copied_syn > 0)
1097                         goto out;
1098                 else if (err)
1099                         goto out_err;
1100         }
1101 
1102         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
1103 
1104         /* Wait for a connection to finish. One exception is TCP Fast Open
1105          * (passive side) where data is allowed to be sent before a connection
1106          * is fully established.
1107          */
1108         if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
1109             !tcp_passive_fastopen(sk)) {
1110                 err = sk_stream_wait_connect(sk, &timeo);
1111                 if (err != 0)
1112                         goto do_error;
1113         }
1114 
1115         if (unlikely(tp->repair)) {
1116                 if (tp->repair_queue == TCP_RECV_QUEUE) {
1117                         copied = tcp_send_rcvq(sk, msg, size);
1118                         goto out_nopush;
1119                 }
1120 
1121                 err = -EINVAL;
1122                 if (tp->repair_queue == TCP_NO_QUEUE)
1123                         goto out_err;
1124 
1125                 /* 'common' sending to sendq */
1126         }
1127 
1128         sockc.tsflags = sk->sk_tsflags;
1129         if (msg->msg_controllen) {
1130                 err = sock_cmsg_send(sk, msg, &sockc);
1131                 if (unlikely(err)) {
1132                         err = -EINVAL;
1133                         goto out_err;
1134                 }
1135         }
1136 
1137         /* This should be in poll */
1138         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
1139 
1140         /* Ok commence sending. */
1141         copied = 0;
1142 
1143 restart:
1144         mss_now = tcp_send_mss(sk, &size_goal, flags);
1145 
1146         err = -EPIPE;
1147         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
1148                 goto out_err;
1149 
1150         sg = !!(sk->sk_route_caps & NETIF_F_SG);
1151 
1152         while (msg_data_left(msg)) {
1153                 int copy = 0;
1154                 int max = size_goal;
1155 
1156                 skb = tcp_write_queue_tail(sk);
1157                 if (tcp_send_head(sk)) {
1158                         if (skb->ip_summed == CHECKSUM_NONE)
1159                                 max = mss_now;
1160                         copy = max - skb->len;
1161                 }
1162 
1163                 if (copy <= 0 || !tcp_skb_can_collapse_to(skb)) {
1164 new_segment:
1165                         /* Allocate new segment. If the interface is SG,
1166                          * allocate skb fitting to single page.
1167                          */
1168                         if (!sk_stream_memory_free(sk))
1169                                 goto wait_for_sndbuf;
1170 
1171                         if (process_backlog && sk_flush_backlog(sk)) {
1172                                 process_backlog = false;
1173                                 goto restart;
1174                         }
1175                         skb = sk_stream_alloc_skb(sk,
1176                                                   select_size(sk, sg),
1177                                                   sk->sk_allocation,
1178                                                   skb_queue_empty(&sk->sk_write_queue));
1179                         if (!skb)
1180                                 goto wait_for_memory;
1181 
1182                         process_backlog = true;
1183                         /*
1184                          * Check whether we can use HW checksum.
1185                          */
1186                         if (sk_check_csum_caps(sk))
1187                                 skb->ip_summed = CHECKSUM_PARTIAL;
1188 
1189                         skb_entail(sk, skb);
1190                         copy = size_goal;
1191                         max = size_goal;
1192 
1193                         /* All packets are restored as if they have
1194                          * already been sent. skb_mstamp isn't set to
1195                          * avoid wrong rtt estimation.
1196                          */
1197                         if (tp->repair)
1198                                 TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
1199                 }
1200 
1201                 /* Try to append data to the end of skb. */
1202                 if (copy > msg_data_left(msg))
1203                         copy = msg_data_left(msg);
1204 
1205                 /* Where to copy to? */
1206                 if (skb_availroom(skb) > 0) {
1207                         /* We have some space in skb head. Superb! */
1208                         copy = min_t(int, copy, skb_availroom(skb));
1209                         err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);
1210                         if (err)
1211                                 goto do_fault;
1212                 } else {
1213                         bool merge = true;
1214                         int i = skb_shinfo(skb)->nr_frags;
1215                         struct page_frag *pfrag = sk_page_frag(sk);
1216 
1217                         if (!sk_page_frag_refill(sk, pfrag))
1218                                 goto wait_for_memory;
1219 
1220                         if (!skb_can_coalesce(skb, i, pfrag->page,
1221                                               pfrag->offset)) {
1222                                 if (i == sysctl_max_skb_frags || !sg) {
1223                                         tcp_mark_push(tp, skb);
1224                                         goto new_segment;
1225                                 }
1226                                 merge = false;
1227                         }
1228 
1229                         copy = min_t(int, copy, pfrag->size - pfrag->offset);
1230 
1231                         if (!sk_wmem_schedule(sk, copy))
1232                                 goto wait_for_memory;
1233 
1234                         err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
1235                                                        pfrag->page,
1236                                                        pfrag->offset,
1237                                                        copy);
1238                         if (err)
1239                                 goto do_error;
1240 
1241                         /* Update the skb. */
1242                         if (merge) {
1243                                 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1244                         } else {
1245                                 skb_fill_page_desc(skb, i, pfrag->page,
1246                                                    pfrag->offset, copy);
1247                                 get_page(pfrag->page);
1248                         }
1249                         pfrag->offset += copy;
1250                 }
1251 
1252                 if (!copied)
1253                         TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1254 
1255                 tp->write_seq += copy;
1256                 TCP_SKB_CB(skb)->end_seq += copy;
1257                 tcp_skb_pcount_set(skb, 0);
1258 
1259                 copied += copy;
1260                 if (!msg_data_left(msg)) {
1261                         tcp_tx_timestamp(sk, sockc.tsflags, skb);
1262                         if (unlikely(flags & MSG_EOR))
1263                                 TCP_SKB_CB(skb)->eor = 1;
1264                         goto out;
1265                 }
1266 
1267                 if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
1268                         continue;
1269 
1270                 if (forced_push(tp)) {
1271                         tcp_mark_push(tp, skb);
1272                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1273                 } else if (skb == tcp_send_head(sk))
1274                         tcp_push_one(sk, mss_now);
1275                 continue;
1276 
1277 wait_for_sndbuf:
1278                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1279 wait_for_memory:
1280                 if (copied)
1281                         tcp_push(sk, flags & ~MSG_MORE, mss_now,
1282                                  TCP_NAGLE_PUSH, size_goal);
1283 
1284                 err = sk_stream_wait_memory(sk, &timeo);
1285                 if (err != 0)
1286                         goto do_error;
1287 
1288                 mss_now = tcp_send_mss(sk, &size_goal, flags);
1289         }
1290 
1291 out:
1292         if (copied)
1293                 tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
1294 out_nopush:
1295         release_sock(sk);
1296         return copied + copied_syn;
1297 
1298 do_fault:
1299         if (!skb->len) {
1300                 tcp_unlink_write_queue(skb, sk);
1301                 /* It is the one place in all of TCP, except connection
1302                  * reset, where we can be unlinking the send_head.
1303                  */
1304                 tcp_check_send_head(sk, skb);
1305                 sk_wmem_free_skb(sk, skb);
1306         }
1307 
1308 do_error:
1309         if (copied + copied_syn)
1310                 goto out;
1311 out_err:
1312         err = sk_stream_error(sk, flags, err);
1313         /* make sure we wake any epoll edge trigger waiter */
1314         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1315                 sk->sk_write_space(sk);
1316         release_sock(sk);
1317         return err;
1318 }
1319 EXPORT_SYMBOL(tcp_sendmsg);
1320 
1321 /*
1322  *      Handle reading urgent data. BSD has very simple semantics for
1323  *      this, no blocking and very strange errors 8)
1324  */
1325 
1326 static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1327 {
1328         struct tcp_sock *tp = tcp_sk(sk);
1329 
1330         /* No URG data to read. */
1331         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1332             tp->urg_data == TCP_URG_READ)
1333                 return -EINVAL; /* Yes this is right ! */
1334 
1335         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1336                 return -ENOTCONN;
1337 
1338         if (tp->urg_data & TCP_URG_VALID) {
1339                 int err = 0;
1340                 char c = tp->urg_data;
1341 
1342                 if (!(flags & MSG_PEEK))
1343                         tp->urg_data = TCP_URG_READ;
1344 
1345                 /* Read urgent data. */
1346                 msg->msg_flags |= MSG_OOB;
1347 
1348                 if (len > 0) {
1349                         if (!(flags & MSG_TRUNC))
1350                                 err = memcpy_to_msg(msg, &c, 1);
1351                         len = 1;
1352                 } else
1353                         msg->msg_flags |= MSG_TRUNC;
1354 
1355                 return err ? -EFAULT : len;
1356         }
1357 
1358         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1359                 return 0;
1360 
1361         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1362          * the available implementations agree in this case:
1363          * this call should never block, independent of the
1364          * blocking state of the socket.
1365          * Mike <pall@rz.uni-karlsruhe.de>
1366          */
1367         return -EAGAIN;
1368 }
1369 
1370 static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len)
1371 {
1372         struct sk_buff *skb;
1373         int copied = 0, err = 0;
1374 
1375         /* XXX -- need to support SO_PEEK_OFF */
1376 
1377         skb_queue_walk(&sk->sk_write_queue, skb) {
1378                 err = skb_copy_datagram_msg(skb, 0, msg, skb->len);
1379                 if (err)
1380                         break;
1381 
1382                 copied += skb->len;
1383         }
1384 
1385         return err ?: copied;
1386 }
1387 
1388 /* Clean up the receive buffer for full frames taken by the user,
1389  * then send an ACK if necessary.  COPIED is the number of bytes
1390  * tcp_recvmsg has given to the user so far, it speeds up the
1391  * calculation of whether or not we must ACK for the sake of
1392  * a window update.
1393  */
1394 static void tcp_cleanup_rbuf(struct sock *sk, int copied)
1395 {
1396         struct tcp_sock *tp = tcp_sk(sk);
1397         bool time_to_ack = false;
1398 
1399         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1400 
1401         WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1402              "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1403              tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1404 
1405         if (inet_csk_ack_scheduled(sk)) {
1406                 const struct inet_connection_sock *icsk = inet_csk(sk);
1407                    /* Delayed ACKs frequently hit locked sockets during bulk
1408                     * receive. */
1409                 if (icsk->icsk_ack.blocked ||
1410                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
1411                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1412                     /*
1413                      * If this read emptied read buffer, we send ACK, if
1414                      * connection is not bidirectional, user drained
1415                      * receive buffer and there was a small segment
1416                      * in queue.
1417                      */
1418                     (copied > 0 &&
1419                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1420                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1421                        !icsk->icsk_ack.pingpong)) &&
1422                       !atomic_read(&sk->sk_rmem_alloc)))
1423                         time_to_ack = true;
1424         }
1425 
1426         /* We send an ACK if we can now advertise a non-zero window
1427          * which has been raised "significantly".
1428          *
1429          * Even if window raised up to infinity, do not send window open ACK
1430          * in states, where we will not receive more. It is useless.
1431          */
1432         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1433                 __u32 rcv_window_now = tcp_receive_window(tp);
1434 
1435                 /* Optimize, __tcp_select_window() is not cheap. */
1436                 if (2*rcv_window_now <= tp->window_clamp) {
1437                         __u32 new_window = __tcp_select_window(sk);
1438 
1439                         /* Send ACK now, if this read freed lots of space
1440                          * in our buffer. Certainly, new_window is new window.
1441                          * We can advertise it now, if it is not less than current one.
1442                          * "Lots" means "at least twice" here.
1443                          */
1444                         if (new_window && new_window >= 2 * rcv_window_now)
1445                                 time_to_ack = true;
1446                 }
1447         }
1448         if (time_to_ack)
1449                 tcp_send_ack(sk);
1450 }
1451 
1452 static void tcp_prequeue_process(struct sock *sk)
1453 {
1454         struct sk_buff *skb;
1455         struct tcp_sock *tp = tcp_sk(sk);
1456 
1457         NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1458 
1459         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1460                 sk_backlog_rcv(sk, skb);
1461 
1462         /* Clear memory counter. */
1463         tp->ucopy.memory = 0;
1464 }
1465 
1466 static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1467 {
1468         struct sk_buff *skb;
1469         u32 offset;
1470 
1471         while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
1472                 offset = seq - TCP_SKB_CB(skb)->seq;
1473                 if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
1474                         pr_err_once("%s: found a SYN, please report !\n", __func__);
1475                         offset--;
1476                 }
1477                 if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {
1478                         *off = offset;
1479                         return skb;
1480                 }
1481                 /* This looks weird, but this can happen if TCP collapsing
1482                  * splitted a fat GRO packet, while we released socket lock
1483                  * in skb_splice_bits()
1484                  */
1485                 sk_eat_skb(sk, skb);
1486         }
1487         return NULL;
1488 }
1489 
1490 /*
1491  * This routine provides an alternative to tcp_recvmsg() for routines
1492  * that would like to handle copying from skbuffs directly in 'sendfile'
1493  * fashion.
1494  * Note:
1495  *      - It is assumed that the socket was locked by the caller.
1496  *      - The routine does not block.
1497  *      - At present, there is no support for reading OOB data
1498  *        or for 'peeking' the socket using this routine
1499  *        (although both would be easy to implement).
1500  */
1501 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1502                   sk_read_actor_t recv_actor)
1503 {
1504         struct sk_buff *skb;
1505         struct tcp_sock *tp = tcp_sk(sk);
1506         u32 seq = tp->copied_seq;
1507         u32 offset;
1508         int copied = 0;
1509 
1510         if (sk->sk_state == TCP_LISTEN)
1511                 return -ENOTCONN;
1512         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1513                 if (offset < skb->len) {
1514                         int used;
1515                         size_t len;
1516 
1517                         len = skb->len - offset;
1518                         /* Stop reading if we hit a patch of urgent data */
1519                         if (tp->urg_data) {
1520                                 u32 urg_offset = tp->urg_seq - seq;
1521                                 if (urg_offset < len)
1522                                         len = urg_offset;
1523                                 if (!len)
1524                                         break;
1525                         }
1526                         used = recv_actor(desc, skb, offset, len);
1527                         if (used <= 0) {
1528                                 if (!copied)
1529                                         copied = used;
1530                                 break;
1531                         } else if (used <= len) {
1532                                 seq += used;
1533                                 copied += used;
1534                                 offset += used;
1535                         }
1536                         /* If recv_actor drops the lock (e.g. TCP splice
1537                          * receive) the skb pointer might be invalid when
1538                          * getting here: tcp_collapse might have deleted it
1539                          * while aggregating skbs from the socket queue.
1540                          */
1541                         skb = tcp_recv_skb(sk, seq - 1, &offset);
1542                         if (!skb)
1543                                 break;
1544                         /* TCP coalescing might have appended data to the skb.
1545                          * Try to splice more frags
1546                          */
1547                         if (offset + 1 != skb->len)
1548                                 continue;
1549                 }
1550                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
1551                         sk_eat_skb(sk, skb);
1552                         ++seq;
1553                         break;
1554                 }
1555                 sk_eat_skb(sk, skb);
1556                 if (!desc->count)
1557                         break;
1558                 tp->copied_seq = seq;
1559         }
1560         tp->copied_seq = seq;
1561 
1562         tcp_rcv_space_adjust(sk);
1563 
1564         /* Clean up data we have read: This will do ACK frames. */
1565         if (copied > 0) {
1566                 tcp_recv_skb(sk, seq, &offset);
1567                 tcp_cleanup_rbuf(sk, copied);
1568         }
1569         return copied;
1570 }
1571 EXPORT_SYMBOL(tcp_read_sock);
1572 
1573 /*
1574  *      This routine copies from a sock struct into the user buffer.
1575  *
1576  *      Technical note: in 2.3 we work on _locked_ socket, so that
1577  *      tricks with *seq access order and skb->users are not required.
1578  *      Probably, code can be easily improved even more.
1579  */
1580 
1581 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
1582                 int flags, int *addr_len)
1583 {
1584         struct tcp_sock *tp = tcp_sk(sk);
1585         int copied = 0;
1586         u32 peek_seq;
1587         u32 *seq;
1588         unsigned long used;
1589         int err;
1590         int target;             /* Read at least this many bytes */
1591         long timeo;
1592         struct task_struct *user_recv = NULL;
1593         struct sk_buff *skb, *last;
1594         u32 urg_hole = 0;
1595 
1596         if (unlikely(flags & MSG_ERRQUEUE))
1597                 return inet_recv_error(sk, msg, len, addr_len);
1598 
1599         if (sk_can_busy_loop(sk) && skb_queue_empty(&sk->sk_receive_queue) &&
1600             (sk->sk_state == TCP_ESTABLISHED))
1601                 sk_busy_loop(sk, nonblock);
1602 
1603         lock_sock(sk);
1604 
1605         err = -ENOTCONN;
1606         if (sk->sk_state == TCP_LISTEN)
1607                 goto out;
1608 
1609         timeo = sock_rcvtimeo(sk, nonblock);
1610 
1611         /* Urgent data needs to be handled specially. */
1612         if (flags & MSG_OOB)
1613                 goto recv_urg;
1614 
1615         if (unlikely(tp->repair)) {
1616                 err = -EPERM;
1617                 if (!(flags & MSG_PEEK))
1618                         goto out;
1619 
1620                 if (tp->repair_queue == TCP_SEND_QUEUE)
1621                         goto recv_sndq;
1622 
1623                 err = -EINVAL;
1624                 if (tp->repair_queue == TCP_NO_QUEUE)
1625                         goto out;
1626 
1627                 /* 'common' recv queue MSG_PEEK-ing */
1628         }
1629 
1630         seq = &tp->copied_seq;
1631         if (flags & MSG_PEEK) {
1632                 peek_seq = tp->copied_seq;
1633                 seq = &peek_seq;
1634         }
1635 
1636         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1637 
1638         do {
1639                 u32 offset;
1640 
1641                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1642                 if (tp->urg_data && tp->urg_seq == *seq) {
1643                         if (copied)
1644                                 break;
1645                         if (signal_pending(current)) {
1646                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1647                                 break;
1648                         }
1649                 }
1650 
1651                 /* Next get a buffer. */
1652 
1653                 last = skb_peek_tail(&sk->sk_receive_queue);
1654                 skb_queue_walk(&sk->sk_receive_queue, skb) {
1655                         last = skb;
1656                         /* Now that we have two receive queues this
1657                          * shouldn't happen.
1658                          */
1659                         if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
1660                                  "recvmsg bug: copied %X seq %X rcvnxt %X fl %X\n",
1661                                  *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
1662                                  flags))
1663                                 break;
1664 
1665                         offset = *seq - TCP_SKB_CB(skb)->seq;
1666                         if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
1667                                 pr_err_once("%s: found a SYN, please report !\n", __func__);
1668                                 offset--;
1669                         }
1670                         if (offset < skb->len)
1671                                 goto found_ok_skb;
1672                         if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
1673                                 goto found_fin_ok;
1674                         WARN(!(flags & MSG_PEEK),
1675                              "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n",
1676                              *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
1677                 }
1678 
1679                 /* Well, if we have backlog, try to process it now yet. */
1680 
1681                 if (copied >= target && !sk->sk_backlog.tail)
1682                         break;
1683 
1684                 if (copied) {
1685                         if (sk->sk_err ||
1686                             sk->sk_state == TCP_CLOSE ||
1687                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1688                             !timeo ||
1689                             signal_pending(current))
1690                                 break;
1691                 } else {
1692                         if (sock_flag(sk, SOCK_DONE))
1693                                 break;
1694 
1695                         if (sk->sk_err) {
1696                                 copied = sock_error(sk);
1697                                 break;
1698                         }
1699 
1700                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1701                                 break;
1702 
1703                         if (sk->sk_state == TCP_CLOSE) {
1704                                 if (!sock_flag(sk, SOCK_DONE)) {
1705                                         /* This occurs when user tries to read
1706                                          * from never connected socket.
1707                                          */
1708                                         copied = -ENOTCONN;
1709                                         break;
1710                                 }
1711                                 break;
1712                         }
1713 
1714                         if (!timeo) {
1715                                 copied = -EAGAIN;
1716                                 break;
1717                         }
1718 
1719                         if (signal_pending(current)) {
1720                                 copied = sock_intr_errno(timeo);
1721                                 break;
1722                         }
1723                 }
1724 
1725                 tcp_cleanup_rbuf(sk, copied);
1726 
1727                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1728                         /* Install new reader */
1729                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1730                                 user_recv = current;
1731                                 tp->ucopy.task = user_recv;
1732                                 tp->ucopy.msg = msg;
1733                         }
1734 
1735                         tp->ucopy.len = len;
1736 
1737                         WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1738                                 !(flags & (MSG_PEEK | MSG_TRUNC)));
1739 
1740                         /* Ugly... If prequeue is not empty, we have to
1741                          * process it before releasing socket, otherwise
1742                          * order will be broken at second iteration.
1743                          * More elegant solution is required!!!
1744                          *
1745                          * Look: we have the following (pseudo)queues:
1746                          *
1747                          * 1. packets in flight
1748                          * 2. backlog
1749                          * 3. prequeue
1750                          * 4. receive_queue
1751                          *
1752                          * Each queue can be processed only if the next ones
1753                          * are empty. At this point we have empty receive_queue.
1754                          * But prequeue _can_ be not empty after 2nd iteration,
1755                          * when we jumped to start of loop because backlog
1756                          * processing added something to receive_queue.
1757                          * We cannot release_sock(), because backlog contains
1758                          * packets arrived _after_ prequeued ones.
1759                          *
1760                          * Shortly, algorithm is clear --- to process all
1761                          * the queues in order. We could make it more directly,
1762                          * requeueing packets from backlog to prequeue, if
1763                          * is not empty. It is more elegant, but eats cycles,
1764                          * unfortunately.
1765                          */
1766                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1767                                 goto do_prequeue;
1768 
1769                         /* __ Set realtime policy in scheduler __ */
1770                 }
1771 
1772                 if (copied >= target) {
1773                         /* Do not sleep, just process backlog. */
1774                         release_sock(sk);
1775                         lock_sock(sk);
1776                 } else {
1777                         sk_wait_data(sk, &timeo, last);
1778                 }
1779 
1780                 if (user_recv) {
1781                         int chunk;
1782 
1783                         /* __ Restore normal policy in scheduler __ */
1784 
1785                         chunk = len - tp->ucopy.len;
1786                         if (chunk != 0) {
1787                                 NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1788                                 len -= chunk;
1789                                 copied += chunk;
1790                         }
1791 
1792                         if (tp->rcv_nxt == tp->copied_seq &&
1793                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1794 do_prequeue:
1795                                 tcp_prequeue_process(sk);
1796 
1797                                 chunk = len - tp->ucopy.len;
1798                                 if (chunk != 0) {
1799                                         NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1800                                         len -= chunk;
1801                                         copied += chunk;
1802                                 }
1803                         }
1804                 }
1805                 if ((flags & MSG_PEEK) &&
1806                     (peek_seq - copied - urg_hole != tp->copied_seq)) {
1807                         net_dbg_ratelimited("TCP(%s:%d): Application bug, race in MSG_PEEK\n",
1808                                             current->comm,
1809                                             task_pid_nr(current));
1810                         peek_seq = tp->copied_seq;
1811                 }
1812                 continue;
1813 
1814         found_ok_skb:
1815                 /* Ok so how much can we use? */
1816                 used = skb->len - offset;
1817                 if (len < used)
1818                         used = len;
1819 
1820                 /* Do we have urgent data here? */
1821                 if (tp->urg_data) {
1822                         u32 urg_offset = tp->urg_seq - *seq;
1823                         if (urg_offset < used) {
1824                                 if (!urg_offset) {
1825                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1826                                                 ++*seq;
1827                                                 urg_hole++;
1828                                                 offset++;
1829                                                 used--;
1830                                                 if (!used)
1831                                                         goto skip_copy;
1832                                         }
1833                                 } else
1834                                         used = urg_offset;
1835                         }
1836                 }
1837 
1838                 if (!(flags & MSG_TRUNC)) {
1839                         err = skb_copy_datagram_msg(skb, offset, msg, used);
1840                         if (err) {
1841                                 /* Exception. Bailout! */
1842                                 if (!copied)
1843                                         copied = -EFAULT;
1844                                 break;
1845                         }
1846                 }
1847 
1848                 *seq += used;
1849                 copied += used;
1850                 len -= used;
1851 
1852                 tcp_rcv_space_adjust(sk);
1853 
1854 skip_copy:
1855                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1856                         tp->urg_data = 0;
1857                         tcp_fast_path_check(sk);
1858                 }
1859                 if (used + offset < skb->len)
1860                         continue;
1861 
1862                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
1863                         goto found_fin_ok;
1864                 if (!(flags & MSG_PEEK))
1865                         sk_eat_skb(sk, skb);
1866                 continue;
1867 
1868         found_fin_ok:
1869                 /* Process the FIN. */
1870                 ++*seq;
1871                 if (!(flags & MSG_PEEK))
1872                         sk_eat_skb(sk, skb);
1873                 break;
1874         } while (len > 0);
1875 
1876         if (user_recv) {
1877                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1878                         int chunk;
1879 
1880                         tp->ucopy.len = copied > 0 ? len : 0;
1881 
1882                         tcp_prequeue_process(sk);
1883 
1884                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1885                                 NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1886                                 len -= chunk;
1887                                 copied += chunk;
1888                         }
1889                 }
1890 
1891                 tp->ucopy.task = NULL;
1892                 tp->ucopy.len = 0;
1893         }
1894 
1895         /* According to UNIX98, msg_name/msg_namelen are ignored
1896          * on connected socket. I was just happy when found this 8) --ANK
1897          */
1898 
1899         /* Clean up data we have read: This will do ACK frames. */
1900         tcp_cleanup_rbuf(sk, copied);
1901 
1902         release_sock(sk);
1903         return copied;
1904 
1905 out:
1906         release_sock(sk);
1907         return err;
1908 
1909 recv_urg:
1910         err = tcp_recv_urg(sk, msg, len, flags);
1911         goto out;
1912 
1913 recv_sndq:
1914         err = tcp_peek_sndq(sk, msg, len);
1915         goto out;
1916 }
1917 EXPORT_SYMBOL(tcp_recvmsg);
1918 
1919 void tcp_set_state(struct sock *sk, int state)
1920 {
1921         int oldstate = sk->sk_state;
1922 
1923         switch (state) {
1924         case TCP_ESTABLISHED:
1925                 if (oldstate != TCP_ESTABLISHED)
1926                         TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1927                 break;
1928 
1929         case TCP_CLOSE:
1930                 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1931                         TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1932 
1933                 sk->sk_prot->unhash(sk);
1934                 if (inet_csk(sk)->icsk_bind_hash &&
1935                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1936                         inet_put_port(sk);
1937                 /* fall through */
1938         default:
1939                 if (oldstate == TCP_ESTABLISHED)
1940                         TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1941         }
1942 
1943         /* Change state AFTER socket is unhashed to avoid closed
1944          * socket sitting in hash tables.
1945          */
1946         sk_state_store(sk, state);
1947 
1948 #ifdef STATE_TRACE
1949         SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1950 #endif
1951 }
1952 EXPORT_SYMBOL_GPL(tcp_set_state);
1953 
1954 /*
1955  *      State processing on a close. This implements the state shift for
1956  *      sending our FIN frame. Note that we only send a FIN for some
1957  *      states. A shutdown() may have already sent the FIN, or we may be
1958  *      closed.
1959  */
1960 
1961 static const unsigned char new_state[16] = {
1962   /* current state:        new state:      action:      */
1963   [0 /* (Invalid) */]   = TCP_CLOSE,
1964   [TCP_ESTABLISHED]     = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1965   [TCP_SYN_SENT]        = TCP_CLOSE,
1966   [TCP_SYN_RECV]        = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1967   [TCP_FIN_WAIT1]       = TCP_FIN_WAIT1,
1968   [TCP_FIN_WAIT2]       = TCP_FIN_WAIT2,
1969   [TCP_TIME_WAIT]       = TCP_CLOSE,
1970   [TCP_CLOSE]           = TCP_CLOSE,
1971   [TCP_CLOSE_WAIT]      = TCP_LAST_ACK  | TCP_ACTION_FIN,
1972   [TCP_LAST_ACK]        = TCP_LAST_ACK,
1973   [TCP_LISTEN]          = TCP_CLOSE,
1974   [TCP_CLOSING]         = TCP_CLOSING,
1975   [TCP_NEW_SYN_RECV]    = TCP_CLOSE,    /* should not happen ! */
1976 };
1977 
1978 static int tcp_close_state(struct sock *sk)
1979 {
1980         int next = (int)new_state[sk->sk_state];
1981         int ns = next & TCP_STATE_MASK;
1982 
1983         tcp_set_state(sk, ns);
1984 
1985         return next & TCP_ACTION_FIN;
1986 }
1987 
1988 /*
1989  *      Shutdown the sending side of a connection. Much like close except
1990  *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
1991  */
1992 
1993 void tcp_shutdown(struct sock *sk, int how)
1994 {
1995         /*      We need to grab some memory, and put together a FIN,
1996          *      and then put it into the queue to be sent.
1997          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1998          */
1999         if (!(how & SEND_SHUTDOWN))
2000                 return;
2001 
2002         /* If we've already sent a FIN, or it's a closed state, skip this. */
2003         if ((1 << sk->sk_state) &
2004             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
2005              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
2006                 /* Clear out any half completed packets.  FIN if needed. */
2007                 if (tcp_close_state(sk))
2008                         tcp_send_fin(sk);
2009         }
2010 }
2011 EXPORT_SYMBOL(tcp_shutdown);
2012 
2013 bool tcp_check_oom(struct sock *sk, int shift)
2014 {
2015         bool too_many_orphans, out_of_socket_memory;
2016 
2017         too_many_orphans = tcp_too_many_orphans(sk, shift);
2018         out_of_socket_memory = tcp_out_of_memory(sk);
2019 
2020         if (too_many_orphans)
2021                 net_info_ratelimited("too many orphaned sockets\n");
2022         if (out_of_socket_memory)
2023                 net_info_ratelimited("out of memory -- consider tuning tcp_mem\n");
2024         return too_many_orphans || out_of_socket_memory;
2025 }
2026 
2027 void tcp_close(struct sock *sk, long timeout)
2028 {
2029         struct sk_buff *skb;
2030         int data_was_unread = 0;
2031         int state;
2032 
2033         lock_sock(sk);
2034         sk->sk_shutdown = SHUTDOWN_MASK;
2035 
2036         if (sk->sk_state == TCP_LISTEN) {
2037                 tcp_set_state(sk, TCP_CLOSE);
2038 
2039                 /* Special case. */
2040                 inet_csk_listen_stop(sk);
2041 
2042                 goto adjudge_to_death;
2043         }
2044 
2045         /*  We need to flush the recv. buffs.  We do this only on the
2046          *  descriptor close, not protocol-sourced closes, because the
2047          *  reader process may not have drained the data yet!
2048          */
2049         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
2050                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq;
2051 
2052                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
2053                         len--;
2054                 data_was_unread += len;
2055                 __kfree_skb(skb);
2056         }
2057 
2058         sk_mem_reclaim(sk);
2059 
2060         /* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
2061         if (sk->sk_state == TCP_CLOSE)
2062                 goto adjudge_to_death;
2063 
2064         /* As outlined in RFC 2525, section 2.17, we send a RST here because
2065          * data was lost. To witness the awful effects of the old behavior of
2066          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
2067          * GET in an FTP client, suspend the process, wait for the client to
2068          * advertise a zero window, then kill -9 the FTP client, wheee...
2069          * Note: timeout is always zero in such a case.
2070          */
2071         if (unlikely(tcp_sk(sk)->repair)) {
2072                 sk->sk_prot->disconnect(sk, 0);
2073         } else if (data_was_unread) {
2074                 /* Unread data was tossed, zap the connection. */
2075                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
2076                 tcp_set_state(sk, TCP_CLOSE);
2077                 tcp_send_active_reset(sk, sk->sk_allocation);
2078         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
2079                 /* Check zero linger _after_ checking for unread data. */
2080                 sk->sk_prot->disconnect(sk, 0);
2081                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
2082         } else if (tcp_close_state(sk)) {
2083                 /* We FIN if the application ate all the data before
2084                  * zapping the connection.
2085                  */
2086 
2087                 /* RED-PEN. Formally speaking, we have broken TCP state
2088                  * machine. State transitions:
2089                  *
2090                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
2091                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
2092                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
2093                  *
2094                  * are legal only when FIN has been sent (i.e. in window),
2095                  * rather than queued out of window. Purists blame.
2096                  *
2097                  * F.e. "RFC state" is ESTABLISHED,
2098                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
2099                  *
2100                  * The visible declinations are that sometimes
2101                  * we enter time-wait state, when it is not required really
2102                  * (harmless), do not send active resets, when they are
2103                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
2104                  * they look as CLOSING or LAST_ACK for Linux)
2105                  * Probably, I missed some more holelets.
2106                  *                                              --ANK
2107                  * XXX (TFO) - To start off we don't support SYN+ACK+FIN
2108                  * in a single packet! (May consider it later but will
2109                  * probably need API support or TCP_CORK SYN-ACK until
2110                  * data is written and socket is closed.)
2111                  */
2112                 tcp_send_fin(sk);
2113         }
2114 
2115         sk_stream_wait_close(sk, timeout);
2116 
2117 adjudge_to_death:
2118         state = sk->sk_state;
2119         sock_hold(sk);
2120         sock_orphan(sk);
2121 
2122         /* It is the last release_sock in its life. It will remove backlog. */
2123         release_sock(sk);
2124 
2125 
2126         /* Now socket is owned by kernel and we acquire BH lock
2127            to finish close. No need to check for user refs.
2128          */
2129         local_bh_disable();
2130         bh_lock_sock(sk);
2131         WARN_ON(sock_owned_by_user(sk));
2132 
2133         percpu_counter_inc(sk->sk_prot->orphan_count);
2134 
2135         /* Have we already been destroyed by a softirq or backlog? */
2136         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
2137                 goto out;
2138 
2139         /*      This is a (useful) BSD violating of the RFC. There is a
2140          *      problem with TCP as specified in that the other end could
2141          *      keep a socket open forever with no application left this end.
2142          *      We use a 1 minute timeout (about the same as BSD) then kill
2143          *      our end. If they send after that then tough - BUT: long enough
2144          *      that we won't make the old 4*rto = almost no time - whoops
2145          *      reset mistake.
2146          *
2147          *      Nope, it was not mistake. It is really desired behaviour
2148          *      f.e. on http servers, when such sockets are useless, but
2149          *      consume significant resources. Let's do it with special
2150          *      linger2 option.                                 --ANK
2151          */
2152 
2153         if (sk->sk_state == TCP_FIN_WAIT2) {
2154                 struct tcp_sock *tp = tcp_sk(sk);
2155                 if (tp->linger2 < 0) {
2156                         tcp_set_state(sk, TCP_CLOSE);
2157                         tcp_send_active_reset(sk, GFP_ATOMIC);
2158                         __NET_INC_STATS(sock_net(sk),
2159                                         LINUX_MIB_TCPABORTONLINGER);
2160                 } else {
2161                         const int tmo = tcp_fin_time(sk);
2162 
2163                         if (tmo > TCP_TIMEWAIT_LEN) {
2164                                 inet_csk_reset_keepalive_timer(sk,
2165                                                 tmo - TCP_TIMEWAIT_LEN);
2166                         } else {
2167                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2168                                 goto out;
2169                         }
2170                 }
2171         }
2172         if (sk->sk_state != TCP_CLOSE) {
2173                 sk_mem_reclaim(sk);
2174                 if (tcp_check_oom(sk, 0)) {
2175                         tcp_set_state(sk, TCP_CLOSE);
2176                         tcp_send_active_reset(sk, GFP_ATOMIC);
2177                         __NET_INC_STATS(sock_net(sk),
2178                                         LINUX_MIB_TCPABORTONMEMORY);
2179                 }
2180         }
2181 
2182         if (sk->sk_state == TCP_CLOSE) {
2183                 struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
2184                 /* We could get here with a non-NULL req if the socket is
2185                  * aborted (e.g., closed with unread data) before 3WHS
2186                  * finishes.
2187                  */
2188                 if (req)
2189                         reqsk_fastopen_remove(sk, req, false);
2190                 inet_csk_destroy_sock(sk);
2191         }
2192         /* Otherwise, socket is reprieved until protocol close. */
2193 
2194 out:
2195         bh_unlock_sock(sk);
2196         local_bh_enable();
2197         sock_put(sk);
2198 }
2199 EXPORT_SYMBOL(tcp_close);
2200 
2201 /* These states need RST on ABORT according to RFC793 */
2202 
2203 static inline bool tcp_need_reset(int state)
2204 {
2205         return (1 << state) &
2206                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2207                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2208 }
2209 
2210 int tcp_disconnect(struct sock *sk, int flags)
2211 {
2212         struct inet_sock *inet = inet_sk(sk);
2213         struct inet_connection_sock *icsk = inet_csk(sk);
2214         struct tcp_sock *tp = tcp_sk(sk);
2215         int err = 0;
2216         int old_state = sk->sk_state;
2217 
2218         if (old_state != TCP_CLOSE)
2219                 tcp_set_state(sk, TCP_CLOSE);
2220 
2221         /* ABORT function of RFC793 */
2222         if (old_state == TCP_LISTEN) {
2223                 inet_csk_listen_stop(sk);
2224         } else if (unlikely(tp->repair)) {
2225                 sk->sk_err = ECONNABORTED;
2226         } else if (tcp_need_reset(old_state) ||
2227                    (tp->snd_nxt != tp->write_seq &&
2228                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2229                 /* The last check adjusts for discrepancy of Linux wrt. RFC
2230                  * states
2231                  */
2232                 tcp_send_active_reset(sk, gfp_any());
2233                 sk->sk_err = ECONNRESET;
2234         } else if (old_state == TCP_SYN_SENT)
2235                 sk->sk_err = ECONNRESET;
2236 
2237         tcp_clear_xmit_timers(sk);
2238         __skb_queue_purge(&sk->sk_receive_queue);
2239         tcp_write_queue_purge(sk);
2240         __skb_queue_purge(&tp->out_of_order_queue);
2241 
2242         inet->inet_dport = 0;
2243 
2244         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2245                 inet_reset_saddr(sk);
2246 
2247         sk->sk_shutdown = 0;
2248         sock_reset_flag(sk, SOCK_DONE);
2249         tp->srtt_us = 0;
2250         tp->write_seq += tp->max_window + 2;
2251         if (tp->write_seq == 0)
2252                 tp->write_seq = 1;
2253         icsk->icsk_backoff = 0;
2254         tp->snd_cwnd = 2;
2255         icsk->icsk_probes_out = 0;
2256         tp->packets_out = 0;
2257         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2258         tp->snd_cwnd_cnt = 0;
2259         tp->window_clamp = 0;
2260         tcp_set_ca_state(sk, TCP_CA_Open);
2261         tcp_clear_retrans(tp);
2262         inet_csk_delack_init(sk);
2263         tcp_init_send_head(sk);
2264         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2265         __sk_dst_reset(sk);
2266 
2267         WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
2268 
2269         sk->sk_error_report(sk);
2270         return err;
2271 }
2272 EXPORT_SYMBOL(tcp_disconnect);
2273 
2274 static inline bool tcp_can_repair_sock(const struct sock *sk)
2275 {
2276         return ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) &&
2277                 ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
2278 }
2279 
2280 static int tcp_repair_options_est(struct tcp_sock *tp,
2281                 struct tcp_repair_opt __user *optbuf, unsigned int len)
2282 {
2283         struct tcp_repair_opt opt;
2284 
2285         while (len >= sizeof(opt)) {
2286                 if (copy_from_user(&opt, optbuf, sizeof(opt)))
2287                         return -EFAULT;
2288 
2289                 optbuf++;
2290                 len -= sizeof(opt);
2291 
2292                 switch (opt.opt_code) {
2293                 case TCPOPT_MSS:
2294                         tp->rx_opt.mss_clamp = opt.opt_val;
2295                         break;
2296                 case TCPOPT_WINDOW:
2297                         {
2298                                 u16 snd_wscale = opt.opt_val & 0xFFFF;
2299                                 u16 rcv_wscale = opt.opt_val >> 16;
2300 
2301                                 if (snd_wscale > 14 || rcv_wscale > 14)
2302                                         return -EFBIG;
2303 
2304                                 tp->rx_opt.snd_wscale = snd_wscale;
2305                                 tp->rx_opt.rcv_wscale = rcv_wscale;
2306                                 tp->rx_opt.wscale_ok = 1;
2307                         }
2308                         break;
2309                 case TCPOPT_SACK_PERM:
2310                         if (opt.opt_val != 0)
2311                                 return -EINVAL;
2312 
2313                         tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
2314                         if (sysctl_tcp_fack)
2315                                 tcp_enable_fack(tp);
2316                         break;
2317                 case TCPOPT_TIMESTAMP:
2318                         if (opt.opt_val != 0)
2319                                 return -EINVAL;
2320 
2321                         tp->rx_opt.tstamp_ok = 1;
2322                         break;
2323                 }
2324         }
2325 
2326         return 0;
2327 }
2328 
2329 /*
2330  *      Socket option code for TCP.
2331  */
2332 static int do_tcp_setsockopt(struct sock *sk, int level,
2333                 int optname, char __user *optval, unsigned int optlen)
2334 {
2335         struct tcp_sock *tp = tcp_sk(sk);
2336         struct inet_connection_sock *icsk = inet_csk(sk);
2337         struct net *net = sock_net(sk);
2338         int val;
2339         int err = 0;
2340 
2341         /* These are data/string values, all the others are ints */
2342         switch (optname) {
2343         case TCP_CONGESTION: {
2344                 char name[TCP_CA_NAME_MAX];
2345 
2346                 if (optlen < 1)
2347                         return -EINVAL;
2348 
2349                 val = strncpy_from_user(name, optval,
2350                                         min_t(long, TCP_CA_NAME_MAX-1, optlen));
2351                 if (val < 0)
2352                         return -EFAULT;
2353                 name[val] = 0;
2354 
2355                 lock_sock(sk);
2356                 err = tcp_set_congestion_control(sk, name);
2357                 release_sock(sk);
2358                 return err;
2359         }
2360         default:
2361                 /* fallthru */
2362                 break;
2363         }
2364 
2365         if (optlen < sizeof(int))
2366                 return -EINVAL;
2367 
2368         if (get_user(val, (int __user *)optval))
2369                 return -EFAULT;
2370 
2371         lock_sock(sk);
2372 
2373         switch (optname) {
2374         case TCP_MAXSEG:
2375                 /* Values greater than interface MTU won't take effect. However
2376                  * at the point when this call is done we typically don't yet
2377                  * know which interface is going to be used */
2378                 if (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW) {
2379                         err = -EINVAL;
2380                         break;
2381                 }
2382                 tp->rx_opt.user_mss = val;
2383                 break;
2384 
2385         case TCP_NODELAY:
2386                 if (val) {
2387                         /* TCP_NODELAY is weaker than TCP_CORK, so that
2388                          * this option on corked socket is remembered, but
2389                          * it is not activated until cork is cleared.
2390                          *
2391                          * However, when TCP_NODELAY is set we make
2392                          * an explicit push, which overrides even TCP_CORK
2393                          * for currently queued segments.
2394                          */
2395                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2396                         tcp_push_pending_frames(sk);
2397                 } else {
2398                         tp->nonagle &= ~TCP_NAGLE_OFF;
2399                 }
2400                 break;
2401 
2402         case TCP_THIN_LINEAR_TIMEOUTS:
2403                 if (val < 0 || val > 1)
2404                         err = -EINVAL;
2405                 else
2406                         tp->thin_lto = val;
2407                 break;
2408 
2409         case TCP_THIN_DUPACK:
2410                 if (val < 0 || val > 1)
2411                         err = -EINVAL;
2412                 else {
2413                         tp->thin_dupack = val;
2414                         if (tp->thin_dupack)
2415                                 tcp_disable_early_retrans(tp);
2416                 }
2417                 break;
2418 
2419         case TCP_REPAIR:
2420                 if (!tcp_can_repair_sock(sk))
2421                         err = -EPERM;
2422                 else if (val == 1) {
2423                         tp->repair = 1;
2424                         sk->sk_reuse = SK_FORCE_REUSE;
2425                         tp->repair_queue = TCP_NO_QUEUE;
2426                 } else if (val == 0) {
2427                         tp->repair = 0;
2428                         sk->sk_reuse = SK_NO_REUSE;
2429                         tcp_send_window_probe(sk);
2430                 } else
2431                         err = -EINVAL;
2432 
2433                 break;
2434 
2435         case TCP_REPAIR_QUEUE:
2436                 if (!tp->repair)
2437                         err = -EPERM;
2438                 else if (val < TCP_QUEUES_NR)
2439                         tp->repair_queue = val;
2440                 else
2441                         err = -EINVAL;
2442                 break;
2443 
2444         case TCP_QUEUE_SEQ:
2445                 if (sk->sk_state != TCP_CLOSE)
2446                         err = -EPERM;
2447                 else if (tp->repair_queue == TCP_SEND_QUEUE)
2448                         tp->write_seq = val;
2449                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2450                         tp->rcv_nxt = val;
2451                 else
2452                         err = -EINVAL;
2453                 break;
2454 
2455         case TCP_REPAIR_OPTIONS:
2456                 if (!tp->repair)
2457                         err = -EINVAL;
2458                 else if (sk->sk_state == TCP_ESTABLISHED)
2459                         err = tcp_repair_options_est(tp,
2460                                         (struct tcp_repair_opt __user *)optval,
2461                                         optlen);
2462                 else
2463                         err = -EPERM;
2464                 break;
2465 
2466         case TCP_CORK:
2467                 /* When set indicates to always queue non-full frames.
2468                  * Later the user clears this option and we transmit
2469                  * any pending partial frames in the queue.  This is
2470                  * meant to be used alongside sendfile() to get properly
2471                  * filled frames when the user (for example) must write
2472                  * out headers with a write() call first and then use
2473                  * sendfile to send out the data parts.
2474                  *
2475                  * TCP_CORK can be set together with TCP_NODELAY and it is
2476                  * stronger than TCP_NODELAY.
2477                  */
2478                 if (val) {
2479                         tp->nonagle |= TCP_NAGLE_CORK;
2480                 } else {
2481                         tp->nonagle &= ~TCP_NAGLE_CORK;
2482                         if (tp->nonagle&TCP_NAGLE_OFF)
2483                                 tp->nonagle |= TCP_NAGLE_PUSH;
2484                         tcp_push_pending_frames(sk);
2485                 }
2486                 break;
2487 
2488         case TCP_KEEPIDLE:
2489                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
2490                         err = -EINVAL;
2491                 else {
2492                         tp->keepalive_time = val * HZ;
2493                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
2494                             !((1 << sk->sk_state) &
2495                               (TCPF_CLOSE | TCPF_LISTEN))) {
2496                                 u32 elapsed = keepalive_time_elapsed(tp);
2497                                 if (tp->keepalive_time > elapsed)
2498                                         elapsed = tp->keepalive_time - elapsed;
2499                                 else
2500                                         elapsed = 0;
2501                                 inet_csk_reset_keepalive_timer(sk, elapsed);
2502                         }
2503                 }
2504                 break;
2505         case TCP_KEEPINTVL:
2506                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
2507                         err = -EINVAL;
2508                 else
2509                         tp->keepalive_intvl = val * HZ;
2510                 break;
2511         case TCP_KEEPCNT:
2512                 if (val < 1 || val > MAX_TCP_KEEPCNT)
2513                         err = -EINVAL;
2514                 else
2515                         tp->keepalive_probes = val;
2516                 break;
2517         case TCP_SYNCNT:
2518                 if (val < 1 || val > MAX_TCP_SYNCNT)
2519                         err = -EINVAL;
2520                 else
2521                         icsk->icsk_syn_retries = val;
2522                 break;
2523 
2524         case TCP_SAVE_SYN:
2525                 if (val < 0 || val > 1)
2526                         err = -EINVAL;
2527                 else
2528                         tp->save_syn = val;
2529                 break;
2530 
2531         case TCP_LINGER2:
2532                 if (val < 0)
2533                         tp->linger2 = -1;
2534                 else if (val > net->ipv4.sysctl_tcp_fin_timeout / HZ)
2535                         tp->linger2 = 0;
2536                 else
2537                         tp->linger2 = val * HZ;
2538                 break;
2539 
2540         case TCP_DEFER_ACCEPT:
2541                 /* Translate value in seconds to number of retransmits */
2542                 icsk->icsk_accept_queue.rskq_defer_accept =
2543                         secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
2544                                         TCP_RTO_MAX / HZ);
2545                 break;
2546 
2547         case TCP_WINDOW_CLAMP:
2548                 if (!val) {
2549                         if (sk->sk_state != TCP_CLOSE) {
2550                                 err = -EINVAL;
2551                                 break;
2552                         }
2553                         tp->window_clamp = 0;
2554                 } else
2555                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2556                                                 SOCK_MIN_RCVBUF / 2 : val;
2557                 break;
2558 
2559         case TCP_QUICKACK:
2560                 if (!val) {
2561                         icsk->icsk_ack.pingpong = 1;
2562                 } else {
2563                         icsk->icsk_ack.pingpong = 0;
2564                         if ((1 << sk->sk_state) &
2565                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2566                             inet_csk_ack_scheduled(sk)) {
2567                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2568                                 tcp_cleanup_rbuf(sk, 1);
2569                                 if (!(val & 1))
2570                                         icsk->icsk_ack.pingpong = 1;
2571                         }
2572                 }
2573                 break;
2574 
2575 #ifdef CONFIG_TCP_MD5SIG
2576         case TCP_MD5SIG:
2577                 /* Read the IP->Key mappings from userspace */
2578                 err = tp->af_specific->md5_parse(sk, optval, optlen);
2579                 break;
2580 #endif
2581         case TCP_USER_TIMEOUT:
2582                 /* Cap the max time in ms TCP will retry or probe the window
2583                  * before giving up and aborting (ETIMEDOUT) a connection.
2584                  */
2585                 if (val < 0)
2586                         err = -EINVAL;
2587                 else
2588                         icsk->icsk_user_timeout = msecs_to_jiffies(val);
2589                 break;
2590 
2591         case TCP_FASTOPEN:
2592                 if (val >= 0 && ((1 << sk->sk_state) & (TCPF_CLOSE |
2593                     TCPF_LISTEN))) {
2594                         tcp_fastopen_init_key_once(true);
2595 
2596                         fastopen_queue_tune(sk, val);
2597                 } else {
2598                         err = -EINVAL;
2599                 }
2600                 break;
2601         case TCP_TIMESTAMP:
2602                 if (!tp->repair)
2603                         err = -EPERM;
2604                 else
2605                         tp->tsoffset = val - tcp_time_stamp;
2606                 break;
2607         case TCP_NOTSENT_LOWAT:
2608                 tp->notsent_lowat = val;
2609                 sk->sk_write_space(sk);
2610                 break;
2611         default:
2612                 err = -ENOPROTOOPT;
2613                 break;
2614         }
2615 
2616         release_sock(sk);
2617         return err;
2618 }
2619 
2620 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2621                    unsigned int optlen)
2622 {
2623         const struct inet_connection_sock *icsk = inet_csk(sk);
2624 
2625         if (level != SOL_TCP)
2626                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2627                                                      optval, optlen);
2628         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2629 }
2630 EXPORT_SYMBOL(tcp_setsockopt);
2631 
2632 #ifdef CONFIG_COMPAT
2633 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2634                           char __user *optval, unsigned int optlen)
2635 {
2636         if (level != SOL_TCP)
2637                 return inet_csk_compat_setsockopt(sk, level, optname,
2638                                                   optval, optlen);
2639         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2640 }
2641 EXPORT_SYMBOL(compat_tcp_setsockopt);
2642 #endif
2643 
2644 /* Return information about state of tcp endpoint in API format. */
2645 void tcp_get_info(struct sock *sk, struct tcp_info *info)
2646 {
2647         const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
2648         const struct inet_connection_sock *icsk = inet_csk(sk);
2649         u32 now = tcp_time_stamp;
2650         unsigned int start;
2651         int notsent_bytes;
2652         u64 rate64;
2653         u32 rate;
2654 
2655         memset(info, 0, sizeof(*info));
2656         if (sk->sk_type != SOCK_STREAM)
2657                 return;
2658 
2659         info->tcpi_state = sk_state_load(sk);
2660 
2661         info->tcpi_ca_state = icsk->icsk_ca_state;
2662         info->tcpi_retransmits = icsk->icsk_retransmits;
2663         info->tcpi_probes = icsk->icsk_probes_out;
2664         info->tcpi_backoff = icsk->icsk_backoff;
2665 
2666         if (tp->rx_opt.tstamp_ok)
2667                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2668         if (tcp_is_sack(tp))
2669                 info->tcpi_options |= TCPI_OPT_SACK;
2670         if (tp->rx_opt.wscale_ok) {
2671                 info->tcpi_options |= TCPI_OPT_WSCALE;
2672                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2673                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2674         }
2675 
2676         if (tp->ecn_flags & TCP_ECN_OK)
2677                 info->tcpi_options |= TCPI_OPT_ECN;
2678         if (tp->ecn_flags & TCP_ECN_SEEN)
2679                 info->tcpi_options |= TCPI_OPT_ECN_SEEN;
2680         if (tp->syn_data_acked)
2681                 info->tcpi_options |= TCPI_OPT_SYN_DATA;
2682 
2683         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2684         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2685         info->tcpi_snd_mss = tp->mss_cache;
2686         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2687 
2688         if (info->tcpi_state == TCP_LISTEN) {
2689                 info->tcpi_unacked = sk->sk_ack_backlog;
2690                 info->tcpi_sacked = sk->sk_max_ack_backlog;
2691         } else {
2692                 info->tcpi_unacked = tp->packets_out;
2693                 info->tcpi_sacked = tp->sacked_out;
2694         }
2695         info->tcpi_lost = tp->lost_out;
2696         info->tcpi_retrans = tp->retrans_out;
2697         info->tcpi_fackets = tp->fackets_out;
2698 
2699         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2700         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2701         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2702 
2703         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2704         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2705         info->tcpi_rtt = tp->srtt_us >> 3;
2706         info->tcpi_rttvar = tp->mdev_us >> 2;
2707         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2708         info->tcpi_snd_cwnd = tp->snd_cwnd;
2709         info->tcpi_advmss = tp->advmss;
2710         info->tcpi_reordering = tp->reordering;
2711 
2712         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2713         info->tcpi_rcv_space = tp->rcvq_space.space;
2714 
2715         info->tcpi_total_retrans = tp->total_retrans;
2716 
2717         rate = READ_ONCE(sk->sk_pacing_rate);
2718         rate64 = rate != ~0U ? rate : ~0ULL;
2719         put_unaligned(rate64, &info->tcpi_pacing_rate);
2720 
2721         rate = READ_ONCE(sk->sk_max_pacing_rate);
2722         rate64 = rate != ~0U ? rate : ~0ULL;
2723         put_unaligned(rate64, &info->tcpi_max_pacing_rate);
2724 
2725         do {
2726                 start = u64_stats_fetch_begin_irq(&tp->syncp);
2727                 put_unaligned(tp->bytes_acked, &info->tcpi_bytes_acked);
2728                 put_unaligned(tp->bytes_received, &info->tcpi_bytes_received);
2729         } while (u64_stats_fetch_retry_irq(&tp->syncp, start));
2730         info->tcpi_segs_out = tp->segs_out;
2731         info->tcpi_segs_in = tp->segs_in;
2732 
2733         notsent_bytes = READ_ONCE(tp->write_seq) - READ_ONCE(tp->snd_nxt);
2734         info->tcpi_notsent_bytes = max(0, notsent_bytes);
2735 
2736         info->tcpi_min_rtt = tcp_min_rtt(tp);
2737         info->tcpi_data_segs_in = tp->data_segs_in;
2738         info->tcpi_data_segs_out = tp->data_segs_out;
2739 }
2740 EXPORT_SYMBOL_GPL(tcp_get_info);
2741 
2742 static int do_tcp_getsockopt(struct sock *sk, int level,
2743                 int optname, char __user *optval, int __user *optlen)
2744 {
2745         struct inet_connection_sock *icsk = inet_csk(sk);
2746         struct tcp_sock *tp = tcp_sk(sk);
2747         struct net *net = sock_net(sk);
2748         int val, len;
2749 
2750         if (get_user(len, optlen))
2751                 return -EFAULT;
2752 
2753         len = min_t(unsigned int, len, sizeof(int));
2754 
2755         if (len < 0)
2756                 return -EINVAL;
2757 
2758         switch (optname) {
2759         case TCP_MAXSEG:
2760                 val = tp->mss_cache;
2761                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2762                         val = tp->rx_opt.user_mss;
2763                 if (tp->repair)
2764                         val = tp->rx_opt.mss_clamp;
2765                 break;
2766         case TCP_NODELAY:
2767                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2768                 break;
2769         case TCP_CORK:
2770                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2771                 break;
2772         case TCP_KEEPIDLE:
2773                 val = keepalive_time_when(tp) / HZ;
2774                 break;
2775         case TCP_KEEPINTVL:
2776                 val = keepalive_intvl_when(tp) / HZ;
2777                 break;
2778         case TCP_KEEPCNT:
2779                 val = keepalive_probes(tp);
2780                 break;
2781         case TCP_SYNCNT:
2782                 val = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
2783                 break;
2784         case TCP_LINGER2:
2785                 val = tp->linger2;
2786                 if (val >= 0)
2787                         val = (val ? : net->ipv4.sysctl_tcp_fin_timeout) / HZ;
2788                 break;
2789         case TCP_DEFER_ACCEPT:
2790                 val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
2791                                       TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
2792                 break;
2793         case TCP_WINDOW_CLAMP:
2794                 val = tp->window_clamp;
2795                 break;
2796         case TCP_INFO: {
2797                 struct tcp_info info;
2798 
2799                 if (get_user(len, optlen))
2800                         return -EFAULT;
2801 
2802                 tcp_get_info(sk, &info);
2803 
2804                 len = min_t(unsigned int, len, sizeof(info));
2805                 if (put_user(len, optlen))
2806                         return -EFAULT;
2807                 if (copy_to_user(optval, &info, len))
2808                         return -EFAULT;
2809                 return 0;
2810         }
2811         case TCP_CC_INFO: {
2812                 const struct tcp_congestion_ops *ca_ops;
2813                 union tcp_cc_info info;
2814                 size_t sz = 0;
2815                 int attr;
2816 
2817                 if (get_user(len, optlen))
2818                         return -EFAULT;
2819 
2820                 ca_ops = icsk->icsk_ca_ops;
2821                 if (ca_ops && ca_ops->get_info)
2822                         sz = ca_ops->get_info(sk, ~0U, &attr, &info);
2823 
2824                 len = min_t(unsigned int, len, sz);
2825                 if (put_user(len, optlen))
2826                         return -EFAULT;
2827                 if (copy_to_user(optval, &info, len))
2828                         return -EFAULT;
2829                 return 0;
2830         }
2831         case TCP_QUICKACK:
2832                 val = !icsk->icsk_ack.pingpong;
2833                 break;
2834 
2835         case TCP_CONGESTION:
2836                 if (get_user(len, optlen))
2837                         return -EFAULT;
2838                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2839                 if (put_user(len, optlen))
2840                         return -EFAULT;
2841                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2842                         return -EFAULT;
2843                 return 0;
2844 
2845         case TCP_THIN_LINEAR_TIMEOUTS:
2846                 val = tp->thin_lto;
2847                 break;
2848         case TCP_THIN_DUPACK:
2849                 val = tp->thin_dupack;
2850                 break;
2851 
2852         case TCP_REPAIR:
2853                 val = tp->repair;
2854                 break;
2855 
2856         case TCP_REPAIR_QUEUE:
2857                 if (tp->repair)
2858                         val = tp->repair_queue;
2859                 else
2860                         return -EINVAL;
2861                 break;
2862 
2863         case TCP_QUEUE_SEQ:
2864                 if (tp->repair_queue == TCP_SEND_QUEUE)
2865                         val = tp->write_seq;
2866                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2867                         val = tp->rcv_nxt;
2868                 else
2869                         return -EINVAL;
2870                 break;
2871 
2872         case TCP_USER_TIMEOUT:
2873                 val = jiffies_to_msecs(icsk->icsk_user_timeout);
2874                 break;
2875 
2876         case TCP_FASTOPEN:
2877                 val = icsk->icsk_accept_queue.fastopenq.max_qlen;
2878                 break;
2879 
2880         case TCP_TIMESTAMP:
2881                 val = tcp_time_stamp + tp->tsoffset;
2882                 break;
2883         case TCP_NOTSENT_LOWAT:
2884                 val = tp->notsent_lowat;
2885                 break;
2886         case TCP_SAVE_SYN:
2887                 val = tp->save_syn;
2888                 break;
2889         case TCP_SAVED_SYN: {
2890                 if (get_user(len, optlen))
2891                         return -EFAULT;
2892 
2893                 lock_sock(sk);
2894                 if (tp->saved_syn) {
2895                         if (len < tp->saved_syn[0]) {
2896                                 if (put_user(tp->saved_syn[0], optlen)) {
2897                                         release_sock(sk);
2898                                         return -EFAULT;
2899                                 }
2900                                 release_sock(sk);
2901                                 return -EINVAL;
2902                         }
2903                         len = tp->saved_syn[0];
2904                         if (put_user(len, optlen)) {
2905                                 release_sock(sk);
2906                                 return -EFAULT;
2907                         }
2908                         if (copy_to_user(optval, tp->saved_syn + 1, len)) {
2909                                 release_sock(sk);
2910                                 return -EFAULT;
2911                         }
2912                         tcp_saved_syn_free(tp);
2913                         release_sock(sk);
2914                 } else {
2915                         release_sock(sk);
2916                         len = 0;
2917                         if (put_user(len, optlen))
2918                                 return -EFAULT;
2919                 }
2920                 return 0;
2921         }
2922         default:
2923                 return -ENOPROTOOPT;
2924         }
2925 
2926         if (put_user(len, optlen))
2927                 return -EFAULT;
2928         if (copy_to_user(optval, &val, len))
2929                 return -EFAULT;
2930         return 0;
2931 }
2932 
2933 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2934                    int __user *optlen)
2935 {
2936         struct inet_connection_sock *icsk = inet_csk(sk);
2937 
2938         if (level != SOL_TCP)
2939                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2940                                                      optval, optlen);
2941         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2942 }
2943 EXPORT_SYMBOL(tcp_getsockopt);
2944 
2945 #ifdef CONFIG_COMPAT
2946 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2947                           char __user *optval, int __user *optlen)
2948 {
2949         if (level != SOL_TCP)
2950                 return inet_csk_compat_getsockopt(sk, level, optname,
2951                                                   optval, optlen);
2952         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2953 }
2954 EXPORT_SYMBOL(compat_tcp_getsockopt);
2955 #endif
2956 
2957 #ifdef CONFIG_TCP_MD5SIG
2958 static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool);
2959 static DEFINE_MUTEX(tcp_md5sig_mutex);
2960 static bool tcp_md5sig_pool_populated = false;
2961 
2962 static void __tcp_alloc_md5sig_pool(void)
2963 {
2964         struct crypto_ahash *hash;
2965         int cpu;
2966 
2967         hash = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
2968         if (IS_ERR(hash))
2969                 return;
2970 
2971         for_each_possible_cpu(cpu) {
2972                 struct ahash_request *req;
2973 
2974                 if (per_cpu(tcp_md5sig_pool, cpu).md5_req)
2975                         continue;
2976 
2977                 req = ahash_request_alloc(hash, GFP_KERNEL);
2978                 if (!req)
2979                         return;
2980 
2981                 ahash_request_set_callback(req, 0, NULL, NULL);
2982 
2983                 per_cpu(tcp_md5sig_pool, cpu).md5_req = req;
2984         }
2985         /* before setting tcp_md5sig_pool_populated, we must commit all writes
2986          * to memory. See smp_rmb() in tcp_get_md5sig_pool()
2987          */
2988         smp_wmb();
2989         tcp_md5sig_pool_populated = true;
2990 }
2991 
2992 bool tcp_alloc_md5sig_pool(void)
2993 {
2994         if (unlikely(!tcp_md5sig_pool_populated)) {
2995                 mutex_lock(&tcp_md5sig_mutex);
2996 
2997                 if (!tcp_md5sig_pool_populated)
2998                         __tcp_alloc_md5sig_pool();
2999 
3000                 mutex_unlock(&tcp_md5sig_mutex);
3001         }
3002         return tcp_md5sig_pool_populated;
3003 }
3004 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
3005 
3006 
3007 /**
3008  *      tcp_get_md5sig_pool - get md5sig_pool for this user
3009  *
3010  *      We use percpu structure, so if we succeed, we exit with preemption
3011  *      and BH disabled, to make sure another thread or softirq handling
3012  *      wont try to get same context.
3013  */
3014 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
3015 {
3016         local_bh_disable();
3017 
3018         if (tcp_md5sig_pool_populated) {
3019                 /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
3020                 smp_rmb();
3021                 return this_cpu_ptr(&tcp_md5sig_pool);
3022         }
3023         local_bh_enable();
3024         return NULL;
3025 }
3026 EXPORT_SYMBOL(tcp_get_md5sig_pool);
3027 
3028 int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
3029                         const struct tcphdr *th)
3030 {
3031         struct scatterlist sg;
3032         struct tcphdr hdr;
3033 
3034         /* We are not allowed to change tcphdr, make a local copy */
3035         memcpy(&hdr, th, sizeof(hdr));
3036         hdr.check = 0;
3037 
3038         /* options aren't included in the hash */
3039         sg_init_one(&sg, &hdr, sizeof(hdr));
3040         ahash_request_set_crypt(hp->md5_req, &sg, NULL, sizeof(hdr));
3041         return crypto_ahash_update(hp->md5_req);
3042 }
3043 EXPORT_SYMBOL(tcp_md5_hash_header);
3044 
3045 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
3046                           const struct sk_buff *skb, unsigned int header_len)
3047 {
3048         struct scatterlist sg;
3049         const struct tcphdr *tp = tcp_hdr(skb);
3050         struct ahash_request *req = hp->md5_req;
3051         unsigned int i;
3052         const unsigned int head_data_len = skb_headlen(skb) > header_len ?
3053                                            skb_headlen(skb) - header_len : 0;
3054         const struct skb_shared_info *shi = skb_shinfo(skb);
3055         struct sk_buff *frag_iter;
3056 
3057         sg_init_table(&sg, 1);
3058 
3059         sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
3060         ahash_request_set_crypt(req, &sg, NULL, head_data_len);
3061         if (crypto_ahash_update(req))
3062                 return 1;
3063 
3064         for (i = 0; i < shi->nr_frags; ++i) {
3065                 const struct skb_frag_struct *f = &shi->frags[i];
3066                 unsigned int offset = f->page_offset;
3067                 struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
3068 
3069                 sg_set_page(&sg, page, skb_frag_size(f),
3070                             offset_in_page(offset));
3071                 ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(f));
3072                 if (crypto_ahash_update(req))
3073                         return 1;
3074         }
3075 
3076         skb_walk_frags(skb, frag_iter)
3077                 if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
3078                         return 1;
3079 
3080         return 0;
3081 }
3082 EXPORT_SYMBOL(tcp_md5_hash_skb_data);
3083 
3084 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key)
3085 {
3086         struct scatterlist sg;
3087 
3088         sg_init_one(&sg, key->key, key->keylen);
3089         ahash_request_set_crypt(hp->md5_req, &sg, NULL, key->keylen);
3090         return crypto_ahash_update(hp->md5_req);
3091 }
3092 EXPORT_SYMBOL(tcp_md5_hash_key);
3093 
3094 #endif
3095 
3096 void tcp_done(struct sock *sk)
3097 {
3098         struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
3099 
3100         if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
3101                 TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
3102 
3103         tcp_set_state(sk, TCP_CLOSE);
3104         tcp_clear_xmit_timers(sk);
3105         if (req)
3106                 reqsk_fastopen_remove(sk, req, false);
3107 
3108         sk->sk_shutdown = SHUTDOWN_MASK;
3109 
3110         if (!sock_flag(sk, SOCK_DEAD))
3111                 sk->sk_state_change(sk);
3112         else
3113                 inet_csk_destroy_sock(sk);
3114 }
3115 EXPORT_SYMBOL_GPL(tcp_done);
3116 
3117 int tcp_abort(struct sock *sk, int err)
3118 {
3119         if (!sk_fullsock(sk)) {
3120                 if (sk->sk_state == TCP_NEW_SYN_RECV) {
3121                         struct request_sock *req = inet_reqsk(sk);
3122 
3123                         local_bh_disable();
3124                         inet_csk_reqsk_queue_drop_and_put(req->rsk_listener,
3125                                                           req);
3126                         local_bh_enable();
3127                         return 0;
3128                 }
3129                 sock_gen_put(sk);
3130                 return -EOPNOTSUPP;
3131         }
3132 
3133         /* Don't race with userspace socket closes such as tcp_close. */
3134         lock_sock(sk);
3135 
3136         if (sk->sk_state == TCP_LISTEN) {
3137                 tcp_set_state(sk, TCP_CLOSE);
3138                 inet_csk_listen_stop(sk);
3139         }
3140 
3141         /* Don't race with BH socket closes such as inet_csk_listen_stop. */
3142         local_bh_disable();
3143         bh_lock_sock(sk);
3144 
3145         if (!sock_flag(sk, SOCK_DEAD)) {
3146                 sk->sk_err = err;
3147                 /* This barrier is coupled with smp_rmb() in tcp_poll() */
3148                 smp_wmb();
3149                 sk->sk_error_report(sk);
3150                 if (tcp_need_reset(sk->sk_state))
3151                         tcp_send_active_reset(sk, GFP_ATOMIC);
3152                 tcp_done(sk);
3153         }
3154 
3155         bh_unlock_sock(sk);
3156         local_bh_enable();
3157         release_sock(sk);
3158         sock_put(sk);
3159         return 0;
3160 }
3161 EXPORT_SYMBOL_GPL(tcp_abort);
3162 
3163 extern struct tcp_congestion_ops tcp_reno;
3164 
3165 static __initdata unsigned long thash_entries;
3166 static int __init set_thash_entries(char *str)
3167 {
3168         ssize_t ret;
3169 
3170         if (!str)
3171                 return 0;
3172 
3173         ret = kstrtoul(str, 0, &thash_entries);
3174         if (ret)
3175                 return 0;
3176 
3177         return 1;
3178 }
3179 __setup("thash_entries=", set_thash_entries);
3180 
3181 static void __init tcp_init_mem(void)
3182 {
3183         unsigned long limit = nr_free_buffer_pages() / 16;
3184 
3185         limit = max(limit, 128UL);
3186         sysctl_tcp_mem[0] = limit / 4 * 3;              /* 4.68 % */
3187         sysctl_tcp_mem[1] = limit;                      /* 6.25 % */
3188         sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;      /* 9.37 % */
3189 }
3190 
3191 void __init tcp_init(void)
3192 {
3193         unsigned long limit;
3194         int max_rshare, max_wshare, cnt;
3195         unsigned int i;
3196 
3197         sock_skb_cb_check_size(sizeof(struct tcp_skb_cb));
3198 
3199         percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
3200         percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL);
3201         tcp_hashinfo.bind_bucket_cachep =
3202                 kmem_cache_create("tcp_bind_bucket",
3203                                   sizeof(struct inet_bind_bucket), 0,
3204                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3205 
3206         /* Size and allocate the main established and bind bucket
3207          * hash tables.
3208          *
3209          * The methodology is similar to that of the buffer cache.
3210          */
3211         tcp_hashinfo.ehash =
3212                 alloc_large_system_hash("TCP established",
3213                                         sizeof(struct inet_ehash_bucket),
3214                                         thash_entries,
3215                                         17, /* one slot per 128 KB of memory */
3216                                         0,
3217                                         NULL,
3218                                         &tcp_hashinfo.ehash_mask,
3219                                         0,
3220                                         thash_entries ? 0 : 512 * 1024);
3221         for (i = 0; i <= tcp_hashinfo.ehash_mask; i++)
3222                 INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
3223 
3224         if (inet_ehash_locks_alloc(&tcp_hashinfo))
3225                 panic("TCP: failed to alloc ehash_locks");
3226         tcp_hashinfo.bhash =
3227                 alloc_large_system_hash("TCP bind",
3228                                         sizeof(struct inet_bind_hashbucket),
3229                                         tcp_hashinfo.ehash_mask + 1,
3230                                         17, /* one slot per 128 KB of memory */
3231                                         0,
3232                                         &tcp_hashinfo.bhash_size,
3233                                         NULL,
3234                                         0,
3235                                         64 * 1024);
3236         tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
3237         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
3238                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
3239                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
3240         }
3241 
3242 
3243         cnt = tcp_hashinfo.ehash_mask + 1;
3244 
3245         tcp_death_row.sysctl_max_tw_buckets = cnt / 2;
3246         sysctl_tcp_max_orphans = cnt / 2;
3247         sysctl_max_syn_backlog = max(128, cnt / 256);
3248 
3249         tcp_init_mem();
3250         /* Set per-socket limits to no more than 1/128 the pressure threshold */
3251         limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
3252         max_wshare = min(4UL*1024*1024, limit);
3253         max_rshare = min(6UL*1024*1024, limit);
3254 
3255         sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
3256         sysctl_tcp_wmem[1] = 16*1024;
3257         sysctl_tcp_wmem[2] = max(64*1024, max_wshare);
3258 
3259         sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
3260         sysctl_tcp_rmem[1] = 87380;
3261         sysctl_tcp_rmem[2] = max(87380, max_rshare);
3262 
3263         pr_info("Hash tables configured (established %u bind %u)\n",
3264                 tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
3265 
3266         tcp_metrics_init();
3267         BUG_ON(tcp_register_congestion_control(&tcp_reno) != 0);
3268         tcp_tasklet_init();
3269 }
3270 

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