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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         tp->out_of_order_queue = RB_ROOT;
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         minmax_reset(&tp->rtt_min, tcp_time_stamp, ~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         /* There's a bubble in the pipe until at least the first ACK. */
400         tp->app_limited = ~0U;
401 
402         /* See draft-stevens-tcpca-spec-01 for discussion of the
403          * initialization of these values.
404          */
405         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
406         tp->snd_cwnd_clamp = ~0;
407         tp->mss_cache = TCP_MSS_DEFAULT;
408         u64_stats_init(&tp->syncp);
409 
410         tp->reordering = sock_net(sk)->ipv4.sysctl_tcp_reordering;
411         tcp_enable_early_retrans(tp);
412         tcp_assign_congestion_control(sk);
413 
414         tp->tsoffset = 0;
415 
416         sk->sk_state = TCP_CLOSE;
417 
418         sk->sk_write_space = sk_stream_write_space;
419         sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
420 
421         icsk->icsk_sync_mss = tcp_sync_mss;
422 
423         sk->sk_sndbuf = sysctl_tcp_wmem[1];
424         sk->sk_rcvbuf = sysctl_tcp_rmem[1];
425 
426         local_bh_disable();
427         sk_sockets_allocated_inc(sk);
428         local_bh_enable();
429 }
430 EXPORT_SYMBOL(tcp_init_sock);
431 
432 static void tcp_tx_timestamp(struct sock *sk, u16 tsflags, struct sk_buff *skb)
433 {
434         if (tsflags) {
435                 struct skb_shared_info *shinfo = skb_shinfo(skb);
436                 struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
437 
438                 sock_tx_timestamp(sk, tsflags, &shinfo->tx_flags);
439                 if (tsflags & SOF_TIMESTAMPING_TX_ACK)
440                         tcb->txstamp_ack = 1;
441                 if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
442                         shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
443         }
444 }
445 
446 /*
447  *      Wait for a TCP event.
448  *
449  *      Note that we don't need to lock the socket, as the upper poll layers
450  *      take care of normal races (between the test and the event) and we don't
451  *      go look at any of the socket buffers directly.
452  */
453 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
454 {
455         unsigned int mask;
456         struct sock *sk = sock->sk;
457         const struct tcp_sock *tp = tcp_sk(sk);
458         int state;
459 
460         sock_rps_record_flow(sk);
461 
462         sock_poll_wait(file, sk_sleep(sk), wait);
463 
464         state = sk_state_load(sk);
465         if (state == TCP_LISTEN)
466                 return inet_csk_listen_poll(sk);
467 
468         /* Socket is not locked. We are protected from async events
469          * by poll logic and correct handling of state changes
470          * made by other threads is impossible in any case.
471          */
472 
473         mask = 0;
474 
475         /*
476          * POLLHUP is certainly not done right. But poll() doesn't
477          * have a notion of HUP in just one direction, and for a
478          * socket the read side is more interesting.
479          *
480          * Some poll() documentation says that POLLHUP is incompatible
481          * with the POLLOUT/POLLWR flags, so somebody should check this
482          * all. But careful, it tends to be safer to return too many
483          * bits than too few, and you can easily break real applications
484          * if you don't tell them that something has hung up!
485          *
486          * Check-me.
487          *
488          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
489          * our fs/select.c). It means that after we received EOF,
490          * poll always returns immediately, making impossible poll() on write()
491          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
492          * if and only if shutdown has been made in both directions.
493          * Actually, it is interesting to look how Solaris and DUX
494          * solve this dilemma. I would prefer, if POLLHUP were maskable,
495          * then we could set it on SND_SHUTDOWN. BTW examples given
496          * in Stevens' books assume exactly this behaviour, it explains
497          * why POLLHUP is incompatible with POLLOUT.    --ANK
498          *
499          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
500          * blocking on fresh not-connected or disconnected socket. --ANK
501          */
502         if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
503                 mask |= POLLHUP;
504         if (sk->sk_shutdown & RCV_SHUTDOWN)
505                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
506 
507         /* Connected or passive Fast Open socket? */
508         if (state != TCP_SYN_SENT &&
509             (state != TCP_SYN_RECV || tp->fastopen_rsk)) {
510                 int target = sock_rcvlowat(sk, 0, INT_MAX);
511 
512                 if (tp->urg_seq == tp->copied_seq &&
513                     !sock_flag(sk, SOCK_URGINLINE) &&
514                     tp->urg_data)
515                         target++;
516 
517                 if (tp->rcv_nxt - tp->copied_seq >= target)
518                         mask |= POLLIN | POLLRDNORM;
519 
520                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
521                         if (sk_stream_is_writeable(sk)) {
522                                 mask |= POLLOUT | POLLWRNORM;
523                         } else {  /* send SIGIO later */
524                                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
525                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
526 
527                                 /* Race breaker. If space is freed after
528                                  * wspace test but before the flags are set,
529                                  * IO signal will be lost. Memory barrier
530                                  * pairs with the input side.
531                                  */
532                                 smp_mb__after_atomic();
533                                 if (sk_stream_is_writeable(sk))
534                                         mask |= POLLOUT | POLLWRNORM;
535                         }
536                 } else
537                         mask |= POLLOUT | POLLWRNORM;
538 
539                 if (tp->urg_data & TCP_URG_VALID)
540                         mask |= POLLPRI;
541         }
542         /* This barrier is coupled with smp_wmb() in tcp_reset() */
543         smp_rmb();
544         if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
545                 mask |= POLLERR;
546 
547         return mask;
548 }
549 EXPORT_SYMBOL(tcp_poll);
550 
551 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
552 {
553         struct tcp_sock *tp = tcp_sk(sk);
554         int answ;
555         bool slow;
556 
557         switch (cmd) {
558         case SIOCINQ:
559                 if (sk->sk_state == TCP_LISTEN)
560                         return -EINVAL;
561 
562                 slow = lock_sock_fast(sk);
563                 answ = tcp_inq(sk);
564                 unlock_sock_fast(sk, slow);
565                 break;
566         case SIOCATMARK:
567                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
568                 break;
569         case SIOCOUTQ:
570                 if (sk->sk_state == TCP_LISTEN)
571                         return -EINVAL;
572 
573                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
574                         answ = 0;
575                 else
576                         answ = tp->write_seq - tp->snd_una;
577                 break;
578         case SIOCOUTQNSD:
579                 if (sk->sk_state == TCP_LISTEN)
580                         return -EINVAL;
581 
582                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
583                         answ = 0;
584                 else
585                         answ = tp->write_seq - tp->snd_nxt;
586                 break;
587         default:
588                 return -ENOIOCTLCMD;
589         }
590 
591         return put_user(answ, (int __user *)arg);
592 }
593 EXPORT_SYMBOL(tcp_ioctl);
594 
595 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
596 {
597         TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
598         tp->pushed_seq = tp->write_seq;
599 }
600 
601 static inline bool forced_push(const struct tcp_sock *tp)
602 {
603         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
604 }
605 
606 static void skb_entail(struct sock *sk, struct sk_buff *skb)
607 {
608         struct tcp_sock *tp = tcp_sk(sk);
609         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
610 
611         skb->csum    = 0;
612         tcb->seq     = tcb->end_seq = tp->write_seq;
613         tcb->tcp_flags = TCPHDR_ACK;
614         tcb->sacked  = 0;
615         __skb_header_release(skb);
616         tcp_add_write_queue_tail(sk, skb);
617         sk->sk_wmem_queued += skb->truesize;
618         sk_mem_charge(sk, skb->truesize);
619         if (tp->nonagle & TCP_NAGLE_PUSH)
620                 tp->nonagle &= ~TCP_NAGLE_PUSH;
621 
622         tcp_slow_start_after_idle_check(sk);
623 }
624 
625 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
626 {
627         if (flags & MSG_OOB)
628                 tp->snd_up = tp->write_seq;
629 }
630 
631 /* If a not yet filled skb is pushed, do not send it if
632  * we have data packets in Qdisc or NIC queues :
633  * Because TX completion will happen shortly, it gives a chance
634  * to coalesce future sendmsg() payload into this skb, without
635  * need for a timer, and with no latency trade off.
636  * As packets containing data payload have a bigger truesize
637  * than pure acks (dataless) packets, the last checks prevent
638  * autocorking if we only have an ACK in Qdisc/NIC queues,
639  * or if TX completion was delayed after we processed ACK packet.
640  */
641 static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
642                                 int size_goal)
643 {
644         return skb->len < size_goal &&
645                sysctl_tcp_autocorking &&
646                skb != tcp_write_queue_head(sk) &&
647                atomic_read(&sk->sk_wmem_alloc) > skb->truesize;
648 }
649 
650 static void tcp_push(struct sock *sk, int flags, int mss_now,
651                      int nonagle, int size_goal)
652 {
653         struct tcp_sock *tp = tcp_sk(sk);
654         struct sk_buff *skb;
655 
656         if (!tcp_send_head(sk))
657                 return;
658 
659         skb = tcp_write_queue_tail(sk);
660         if (!(flags & MSG_MORE) || forced_push(tp))
661                 tcp_mark_push(tp, skb);
662 
663         tcp_mark_urg(tp, flags);
664 
665         if (tcp_should_autocork(sk, skb, size_goal)) {
666 
667                 /* avoid atomic op if TSQ_THROTTLED bit is already set */
668                 if (!test_bit(TSQ_THROTTLED, &tp->tsq_flags)) {
669                         NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTOCORKING);
670                         set_bit(TSQ_THROTTLED, &tp->tsq_flags);
671                 }
672                 /* It is possible TX completion already happened
673                  * before we set TSQ_THROTTLED.
674                  */
675                 if (atomic_read(&sk->sk_wmem_alloc) > skb->truesize)
676                         return;
677         }
678 
679         if (flags & MSG_MORE)
680                 nonagle = TCP_NAGLE_CORK;
681 
682         __tcp_push_pending_frames(sk, mss_now, nonagle);
683 }
684 
685 static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
686                                 unsigned int offset, size_t len)
687 {
688         struct tcp_splice_state *tss = rd_desc->arg.data;
689         int ret;
690 
691         ret = skb_splice_bits(skb, skb->sk, offset, tss->pipe,
692                               min(rd_desc->count, len), tss->flags);
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 
1018         tcp_rate_check_app_limited(sk);  /* is sending application-limited? */
1019 
1020         res = do_tcp_sendpages(sk, page, offset, size, flags);
1021         release_sock(sk);
1022         return res;
1023 }
1024 EXPORT_SYMBOL(tcp_sendpage);
1025 
1026 /* Do not bother using a page frag for very small frames.
1027  * But use this heuristic only for the first skb in write queue.
1028  *
1029  * Having no payload in skb->head allows better SACK shifting
1030  * in tcp_shift_skb_data(), reducing sack/rack overhead, because
1031  * write queue has less skbs.
1032  * Each skb can hold up to MAX_SKB_FRAGS * 32Kbytes, or ~0.5 MB.
1033  * This also speeds up tso_fragment(), since it wont fallback
1034  * to tcp_fragment().
1035  */
1036 static int linear_payload_sz(bool first_skb)
1037 {
1038         if (first_skb)
1039                 return SKB_WITH_OVERHEAD(2048 - MAX_TCP_HEADER);
1040         return 0;
1041 }
1042 
1043 static int select_size(const struct sock *sk, bool sg, bool first_skb)
1044 {
1045         const struct tcp_sock *tp = tcp_sk(sk);
1046         int tmp = tp->mss_cache;
1047 
1048         if (sg) {
1049                 if (sk_can_gso(sk)) {
1050                         tmp = linear_payload_sz(first_skb);
1051                 } else {
1052                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
1053 
1054                         if (tmp >= pgbreak &&
1055                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
1056                                 tmp = pgbreak;
1057                 }
1058         }
1059 
1060         return tmp;
1061 }
1062 
1063 void tcp_free_fastopen_req(struct tcp_sock *tp)
1064 {
1065         if (tp->fastopen_req) {
1066                 kfree(tp->fastopen_req);
1067                 tp->fastopen_req = NULL;
1068         }
1069 }
1070 
1071 static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
1072                                 int *copied, size_t size)
1073 {
1074         struct tcp_sock *tp = tcp_sk(sk);
1075         int err, flags;
1076 
1077         if (!(sysctl_tcp_fastopen & TFO_CLIENT_ENABLE))
1078                 return -EOPNOTSUPP;
1079         if (tp->fastopen_req)
1080                 return -EALREADY; /* Another Fast Open is in progress */
1081 
1082         tp->fastopen_req = kzalloc(sizeof(struct tcp_fastopen_request),
1083                                    sk->sk_allocation);
1084         if (unlikely(!tp->fastopen_req))
1085                 return -ENOBUFS;
1086         tp->fastopen_req->data = msg;
1087         tp->fastopen_req->size = size;
1088 
1089         flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
1090         err = __inet_stream_connect(sk->sk_socket, msg->msg_name,
1091                                     msg->msg_namelen, flags);
1092         *copied = tp->fastopen_req->copied;
1093         tcp_free_fastopen_req(tp);
1094         return err;
1095 }
1096 
1097 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
1098 {
1099         struct tcp_sock *tp = tcp_sk(sk);
1100         struct sk_buff *skb;
1101         struct sockcm_cookie sockc;
1102         int flags, err, copied = 0;
1103         int mss_now = 0, size_goal, copied_syn = 0;
1104         bool process_backlog = false;
1105         bool sg;
1106         long timeo;
1107 
1108         lock_sock(sk);
1109 
1110         flags = msg->msg_flags;
1111         if (flags & MSG_FASTOPEN) {
1112                 err = tcp_sendmsg_fastopen(sk, msg, &copied_syn, size);
1113                 if (err == -EINPROGRESS && copied_syn > 0)
1114                         goto out;
1115                 else if (err)
1116                         goto out_err;
1117         }
1118 
1119         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
1120 
1121         tcp_rate_check_app_limited(sk);  /* is sending application-limited? */
1122 
1123         /* Wait for a connection to finish. One exception is TCP Fast Open
1124          * (passive side) where data is allowed to be sent before a connection
1125          * is fully established.
1126          */
1127         if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
1128             !tcp_passive_fastopen(sk)) {
1129                 err = sk_stream_wait_connect(sk, &timeo);
1130                 if (err != 0)
1131                         goto do_error;
1132         }
1133 
1134         if (unlikely(tp->repair)) {
1135                 if (tp->repair_queue == TCP_RECV_QUEUE) {
1136                         copied = tcp_send_rcvq(sk, msg, size);
1137                         goto out_nopush;
1138                 }
1139 
1140                 err = -EINVAL;
1141                 if (tp->repair_queue == TCP_NO_QUEUE)
1142                         goto out_err;
1143 
1144                 /* 'common' sending to sendq */
1145         }
1146 
1147         sockc.tsflags = sk->sk_tsflags;
1148         if (msg->msg_controllen) {
1149                 err = sock_cmsg_send(sk, msg, &sockc);
1150                 if (unlikely(err)) {
1151                         err = -EINVAL;
1152                         goto out_err;
1153                 }
1154         }
1155 
1156         /* This should be in poll */
1157         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
1158 
1159         /* Ok commence sending. */
1160         copied = 0;
1161 
1162 restart:
1163         mss_now = tcp_send_mss(sk, &size_goal, flags);
1164 
1165         err = -EPIPE;
1166         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
1167                 goto do_error;
1168 
1169         sg = !!(sk->sk_route_caps & NETIF_F_SG);
1170 
1171         while (msg_data_left(msg)) {
1172                 int copy = 0;
1173                 int max = size_goal;
1174 
1175                 skb = tcp_write_queue_tail(sk);
1176                 if (tcp_send_head(sk)) {
1177                         if (skb->ip_summed == CHECKSUM_NONE)
1178                                 max = mss_now;
1179                         copy = max - skb->len;
1180                 }
1181 
1182                 if (copy <= 0 || !tcp_skb_can_collapse_to(skb)) {
1183                         bool first_skb;
1184 
1185 new_segment:
1186                         /* Allocate new segment. If the interface is SG,
1187                          * allocate skb fitting to single page.
1188                          */
1189                         if (!sk_stream_memory_free(sk))
1190                                 goto wait_for_sndbuf;
1191 
1192                         if (process_backlog && sk_flush_backlog(sk)) {
1193                                 process_backlog = false;
1194                                 goto restart;
1195                         }
1196                         first_skb = skb_queue_empty(&sk->sk_write_queue);
1197                         skb = sk_stream_alloc_skb(sk,
1198                                                   select_size(sk, sg, first_skb),
1199                                                   sk->sk_allocation,
1200                                                   first_skb);
1201                         if (!skb)
1202                                 goto wait_for_memory;
1203 
1204                         process_backlog = true;
1205                         /*
1206                          * Check whether we can use HW checksum.
1207                          */
1208                         if (sk_check_csum_caps(sk))
1209                                 skb->ip_summed = CHECKSUM_PARTIAL;
1210 
1211                         skb_entail(sk, skb);
1212                         copy = size_goal;
1213                         max = size_goal;
1214 
1215                         /* All packets are restored as if they have
1216                          * already been sent. skb_mstamp isn't set to
1217                          * avoid wrong rtt estimation.
1218                          */
1219                         if (tp->repair)
1220                                 TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
1221                 }
1222 
1223                 /* Try to append data to the end of skb. */
1224                 if (copy > msg_data_left(msg))
1225                         copy = msg_data_left(msg);
1226 
1227                 /* Where to copy to? */
1228                 if (skb_availroom(skb) > 0) {
1229                         /* We have some space in skb head. Superb! */
1230                         copy = min_t(int, copy, skb_availroom(skb));
1231                         err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);
1232                         if (err)
1233                                 goto do_fault;
1234                 } else {
1235                         bool merge = true;
1236                         int i = skb_shinfo(skb)->nr_frags;
1237                         struct page_frag *pfrag = sk_page_frag(sk);
1238 
1239                         if (!sk_page_frag_refill(sk, pfrag))
1240                                 goto wait_for_memory;
1241 
1242                         if (!skb_can_coalesce(skb, i, pfrag->page,
1243                                               pfrag->offset)) {
1244                                 if (i >= sysctl_max_skb_frags || !sg) {
1245                                         tcp_mark_push(tp, skb);
1246                                         goto new_segment;
1247                                 }
1248                                 merge = false;
1249                         }
1250 
1251                         copy = min_t(int, copy, pfrag->size - pfrag->offset);
1252 
1253                         if (!sk_wmem_schedule(sk, copy))
1254                                 goto wait_for_memory;
1255 
1256                         err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
1257                                                        pfrag->page,
1258                                                        pfrag->offset,
1259                                                        copy);
1260                         if (err)
1261                                 goto do_error;
1262 
1263                         /* Update the skb. */
1264                         if (merge) {
1265                                 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1266                         } else {
1267                                 skb_fill_page_desc(skb, i, pfrag->page,
1268                                                    pfrag->offset, copy);
1269                                 get_page(pfrag->page);
1270                         }
1271                         pfrag->offset += copy;
1272                 }
1273 
1274                 if (!copied)
1275                         TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
1276 
1277                 tp->write_seq += copy;
1278                 TCP_SKB_CB(skb)->end_seq += copy;
1279                 tcp_skb_pcount_set(skb, 0);
1280 
1281                 copied += copy;
1282                 if (!msg_data_left(msg)) {
1283                         tcp_tx_timestamp(sk, sockc.tsflags, skb);
1284                         if (unlikely(flags & MSG_EOR))
1285                                 TCP_SKB_CB(skb)->eor = 1;
1286                         goto out;
1287                 }
1288 
1289                 if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
1290                         continue;
1291 
1292                 if (forced_push(tp)) {
1293                         tcp_mark_push(tp, skb);
1294                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
1295                 } else if (skb == tcp_send_head(sk))
1296                         tcp_push_one(sk, mss_now);
1297                 continue;
1298 
1299 wait_for_sndbuf:
1300                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1301 wait_for_memory:
1302                 if (copied)
1303                         tcp_push(sk, flags & ~MSG_MORE, mss_now,
1304                                  TCP_NAGLE_PUSH, size_goal);
1305 
1306                 err = sk_stream_wait_memory(sk, &timeo);
1307                 if (err != 0)
1308                         goto do_error;
1309 
1310                 mss_now = tcp_send_mss(sk, &size_goal, flags);
1311         }
1312 
1313 out:
1314         if (copied)
1315                 tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
1316 out_nopush:
1317         release_sock(sk);
1318         return copied + copied_syn;
1319 
1320 do_fault:
1321         if (!skb->len) {
1322                 tcp_unlink_write_queue(skb, sk);
1323                 /* It is the one place in all of TCP, except connection
1324                  * reset, where we can be unlinking the send_head.
1325                  */
1326                 tcp_check_send_head(sk, skb);
1327                 sk_wmem_free_skb(sk, skb);
1328         }
1329 
1330 do_error:
1331         if (copied + copied_syn)
1332                 goto out;
1333 out_err:
1334         err = sk_stream_error(sk, flags, err);
1335         /* make sure we wake any epoll edge trigger waiter */
1336         if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
1337                 sk->sk_write_space(sk);
1338         release_sock(sk);
1339         return err;
1340 }
1341 EXPORT_SYMBOL(tcp_sendmsg);
1342 
1343 /*
1344  *      Handle reading urgent data. BSD has very simple semantics for
1345  *      this, no blocking and very strange errors 8)
1346  */
1347 
1348 static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
1349 {
1350         struct tcp_sock *tp = tcp_sk(sk);
1351 
1352         /* No URG data to read. */
1353         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
1354             tp->urg_data == TCP_URG_READ)
1355                 return -EINVAL; /* Yes this is right ! */
1356 
1357         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
1358                 return -ENOTCONN;
1359 
1360         if (tp->urg_data & TCP_URG_VALID) {
1361                 int err = 0;
1362                 char c = tp->urg_data;
1363 
1364                 if (!(flags & MSG_PEEK))
1365                         tp->urg_data = TCP_URG_READ;
1366 
1367                 /* Read urgent data. */
1368                 msg->msg_flags |= MSG_OOB;
1369 
1370                 if (len > 0) {
1371                         if (!(flags & MSG_TRUNC))
1372                                 err = memcpy_to_msg(msg, &c, 1);
1373                         len = 1;
1374                 } else
1375                         msg->msg_flags |= MSG_TRUNC;
1376 
1377                 return err ? -EFAULT : len;
1378         }
1379 
1380         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
1381                 return 0;
1382 
1383         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
1384          * the available implementations agree in this case:
1385          * this call should never block, independent of the
1386          * blocking state of the socket.
1387          * Mike <pall@rz.uni-karlsruhe.de>
1388          */
1389         return -EAGAIN;
1390 }
1391 
1392 static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len)
1393 {
1394         struct sk_buff *skb;
1395         int copied = 0, err = 0;
1396 
1397         /* XXX -- need to support SO_PEEK_OFF */
1398 
1399         skb_queue_walk(&sk->sk_write_queue, skb) {
1400                 err = skb_copy_datagram_msg(skb, 0, msg, skb->len);
1401                 if (err)
1402                         break;
1403 
1404                 copied += skb->len;
1405         }
1406 
1407         return err ?: copied;
1408 }
1409 
1410 /* Clean up the receive buffer for full frames taken by the user,
1411  * then send an ACK if necessary.  COPIED is the number of bytes
1412  * tcp_recvmsg has given to the user so far, it speeds up the
1413  * calculation of whether or not we must ACK for the sake of
1414  * a window update.
1415  */
1416 static void tcp_cleanup_rbuf(struct sock *sk, int copied)
1417 {
1418         struct tcp_sock *tp = tcp_sk(sk);
1419         bool time_to_ack = false;
1420 
1421         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
1422 
1423         WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
1424              "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
1425              tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
1426 
1427         if (inet_csk_ack_scheduled(sk)) {
1428                 const struct inet_connection_sock *icsk = inet_csk(sk);
1429                    /* Delayed ACKs frequently hit locked sockets during bulk
1430                     * receive. */
1431                 if (icsk->icsk_ack.blocked ||
1432                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
1433                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
1434                     /*
1435                      * If this read emptied read buffer, we send ACK, if
1436                      * connection is not bidirectional, user drained
1437                      * receive buffer and there was a small segment
1438                      * in queue.
1439                      */
1440                     (copied > 0 &&
1441                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
1442                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
1443                        !icsk->icsk_ack.pingpong)) &&
1444                       !atomic_read(&sk->sk_rmem_alloc)))
1445                         time_to_ack = true;
1446         }
1447 
1448         /* We send an ACK if we can now advertise a non-zero window
1449          * which has been raised "significantly".
1450          *
1451          * Even if window raised up to infinity, do not send window open ACK
1452          * in states, where we will not receive more. It is useless.
1453          */
1454         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
1455                 __u32 rcv_window_now = tcp_receive_window(tp);
1456 
1457                 /* Optimize, __tcp_select_window() is not cheap. */
1458                 if (2*rcv_window_now <= tp->window_clamp) {
1459                         __u32 new_window = __tcp_select_window(sk);
1460 
1461                         /* Send ACK now, if this read freed lots of space
1462                          * in our buffer. Certainly, new_window is new window.
1463                          * We can advertise it now, if it is not less than current one.
1464                          * "Lots" means "at least twice" here.
1465                          */
1466                         if (new_window && new_window >= 2 * rcv_window_now)
1467                                 time_to_ack = true;
1468                 }
1469         }
1470         if (time_to_ack)
1471                 tcp_send_ack(sk);
1472 }
1473 
1474 static void tcp_prequeue_process(struct sock *sk)
1475 {
1476         struct sk_buff *skb;
1477         struct tcp_sock *tp = tcp_sk(sk);
1478 
1479         NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
1480 
1481         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1482                 sk_backlog_rcv(sk, skb);
1483 
1484         /* Clear memory counter. */
1485         tp->ucopy.memory = 0;
1486 }
1487 
1488 static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1489 {
1490         struct sk_buff *skb;
1491         u32 offset;
1492 
1493         while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
1494                 offset = seq - TCP_SKB_CB(skb)->seq;
1495                 if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
1496                         pr_err_once("%s: found a SYN, please report !\n", __func__);
1497                         offset--;
1498                 }
1499                 if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {
1500                         *off = offset;
1501                         return skb;
1502                 }
1503                 /* This looks weird, but this can happen if TCP collapsing
1504                  * splitted a fat GRO packet, while we released socket lock
1505                  * in skb_splice_bits()
1506                  */
1507                 sk_eat_skb(sk, skb);
1508         }
1509         return NULL;
1510 }
1511 
1512 /*
1513  * This routine provides an alternative to tcp_recvmsg() for routines
1514  * that would like to handle copying from skbuffs directly in 'sendfile'
1515  * fashion.
1516  * Note:
1517  *      - It is assumed that the socket was locked by the caller.
1518  *      - The routine does not block.
1519  *      - At present, there is no support for reading OOB data
1520  *        or for 'peeking' the socket using this routine
1521  *        (although both would be easy to implement).
1522  */
1523 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1524                   sk_read_actor_t recv_actor)
1525 {
1526         struct sk_buff *skb;
1527         struct tcp_sock *tp = tcp_sk(sk);
1528         u32 seq = tp->copied_seq;
1529         u32 offset;
1530         int copied = 0;
1531 
1532         if (sk->sk_state == TCP_LISTEN)
1533                 return -ENOTCONN;
1534         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1535                 if (offset < skb->len) {
1536                         int used;
1537                         size_t len;
1538 
1539                         len = skb->len - offset;
1540                         /* Stop reading if we hit a patch of urgent data */
1541                         if (tp->urg_data) {
1542                                 u32 urg_offset = tp->urg_seq - seq;
1543                                 if (urg_offset < len)
1544                                         len = urg_offset;
1545                                 if (!len)
1546                                         break;
1547                         }
1548                         used = recv_actor(desc, skb, offset, len);
1549                         if (used <= 0) {
1550                                 if (!copied)
1551                                         copied = used;
1552                                 break;
1553                         } else if (used <= len) {
1554                                 seq += used;
1555                                 copied += used;
1556                                 offset += used;
1557                         }
1558                         /* If recv_actor drops the lock (e.g. TCP splice
1559                          * receive) the skb pointer might be invalid when
1560                          * getting here: tcp_collapse might have deleted it
1561                          * while aggregating skbs from the socket queue.
1562                          */
1563                         skb = tcp_recv_skb(sk, seq - 1, &offset);
1564                         if (!skb)
1565                                 break;
1566                         /* TCP coalescing might have appended data to the skb.
1567                          * Try to splice more frags
1568                          */
1569                         if (offset + 1 != skb->len)
1570                                 continue;
1571                 }
1572                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
1573                         sk_eat_skb(sk, skb);
1574                         ++seq;
1575                         break;
1576                 }
1577                 sk_eat_skb(sk, skb);
1578                 if (!desc->count)
1579                         break;
1580                 tp->copied_seq = seq;
1581         }
1582         tp->copied_seq = seq;
1583 
1584         tcp_rcv_space_adjust(sk);
1585 
1586         /* Clean up data we have read: This will do ACK frames. */
1587         if (copied > 0) {
1588                 tcp_recv_skb(sk, seq, &offset);
1589                 tcp_cleanup_rbuf(sk, copied);
1590         }
1591         return copied;
1592 }
1593 EXPORT_SYMBOL(tcp_read_sock);
1594 
1595 int tcp_peek_len(struct socket *sock)
1596 {
1597         return tcp_inq(sock->sk);
1598 }
1599 EXPORT_SYMBOL(tcp_peek_len);
1600 
1601 /*
1602  *      This routine copies from a sock struct into the user buffer.
1603  *
1604  *      Technical note: in 2.3 we work on _locked_ socket, so that
1605  *      tricks with *seq access order and skb->users are not required.
1606  *      Probably, code can be easily improved even more.
1607  */
1608 
1609 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
1610                 int flags, int *addr_len)
1611 {
1612         struct tcp_sock *tp = tcp_sk(sk);
1613         int copied = 0;
1614         u32 peek_seq;
1615         u32 *seq;
1616         unsigned long used;
1617         int err;
1618         int target;             /* Read at least this many bytes */
1619         long timeo;
1620         struct task_struct *user_recv = NULL;
1621         struct sk_buff *skb, *last;
1622         u32 urg_hole = 0;
1623 
1624         if (unlikely(flags & MSG_ERRQUEUE))
1625                 return inet_recv_error(sk, msg, len, addr_len);
1626 
1627         if (sk_can_busy_loop(sk) && skb_queue_empty(&sk->sk_receive_queue) &&
1628             (sk->sk_state == TCP_ESTABLISHED))
1629                 sk_busy_loop(sk, nonblock);
1630 
1631         lock_sock(sk);
1632 
1633         err = -ENOTCONN;
1634         if (sk->sk_state == TCP_LISTEN)
1635                 goto out;
1636 
1637         timeo = sock_rcvtimeo(sk, nonblock);
1638 
1639         /* Urgent data needs to be handled specially. */
1640         if (flags & MSG_OOB)
1641                 goto recv_urg;
1642 
1643         if (unlikely(tp->repair)) {
1644                 err = -EPERM;
1645                 if (!(flags & MSG_PEEK))
1646                         goto out;
1647 
1648                 if (tp->repair_queue == TCP_SEND_QUEUE)
1649                         goto recv_sndq;
1650 
1651                 err = -EINVAL;
1652                 if (tp->repair_queue == TCP_NO_QUEUE)
1653                         goto out;
1654 
1655                 /* 'common' recv queue MSG_PEEK-ing */
1656         }
1657 
1658         seq = &tp->copied_seq;
1659         if (flags & MSG_PEEK) {
1660                 peek_seq = tp->copied_seq;
1661                 seq = &peek_seq;
1662         }
1663 
1664         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1665 
1666         do {
1667                 u32 offset;
1668 
1669                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1670                 if (tp->urg_data && tp->urg_seq == *seq) {
1671                         if (copied)
1672                                 break;
1673                         if (signal_pending(current)) {
1674                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1675                                 break;
1676                         }
1677                 }
1678 
1679                 /* Next get a buffer. */
1680 
1681                 last = skb_peek_tail(&sk->sk_receive_queue);
1682                 skb_queue_walk(&sk->sk_receive_queue, skb) {
1683                         last = skb;
1684                         /* Now that we have two receive queues this
1685                          * shouldn't happen.
1686                          */
1687                         if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
1688                                  "recvmsg bug: copied %X seq %X rcvnxt %X fl %X\n",
1689                                  *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
1690                                  flags))
1691                                 break;
1692 
1693                         offset = *seq - TCP_SKB_CB(skb)->seq;
1694                         if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
1695                                 pr_err_once("%s: found a SYN, please report !\n", __func__);
1696                                 offset--;
1697                         }
1698                         if (offset < skb->len)
1699                                 goto found_ok_skb;
1700                         if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
1701                                 goto found_fin_ok;
1702                         WARN(!(flags & MSG_PEEK),
1703                              "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n",
1704                              *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
1705                 }
1706 
1707                 /* Well, if we have backlog, try to process it now yet. */
1708 
1709                 if (copied >= target && !sk->sk_backlog.tail)
1710                         break;
1711 
1712                 if (copied) {
1713                         if (sk->sk_err ||
1714                             sk->sk_state == TCP_CLOSE ||
1715                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1716                             !timeo ||
1717                             signal_pending(current))
1718                                 break;
1719                 } else {
1720                         if (sock_flag(sk, SOCK_DONE))
1721                                 break;
1722 
1723                         if (sk->sk_err) {
1724                                 copied = sock_error(sk);
1725                                 break;
1726                         }
1727 
1728                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1729                                 break;
1730 
1731                         if (sk->sk_state == TCP_CLOSE) {
1732                                 if (!sock_flag(sk, SOCK_DONE)) {
1733                                         /* This occurs when user tries to read
1734                                          * from never connected socket.
1735                                          */
1736                                         copied = -ENOTCONN;
1737                                         break;
1738                                 }
1739                                 break;
1740                         }
1741 
1742                         if (!timeo) {
1743                                 copied = -EAGAIN;
1744                                 break;
1745                         }
1746 
1747                         if (signal_pending(current)) {
1748                                 copied = sock_intr_errno(timeo);
1749                                 break;
1750                         }
1751                 }
1752 
1753                 tcp_cleanup_rbuf(sk, copied);
1754 
1755                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1756                         /* Install new reader */
1757                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1758                                 user_recv = current;
1759                                 tp->ucopy.task = user_recv;
1760                                 tp->ucopy.msg = msg;
1761                         }
1762 
1763                         tp->ucopy.len = len;
1764 
1765                         WARN_ON(tp->copied_seq != tp->rcv_nxt &&
1766                                 !(flags & (MSG_PEEK | MSG_TRUNC)));
1767 
1768                         /* Ugly... If prequeue is not empty, we have to
1769                          * process it before releasing socket, otherwise
1770                          * order will be broken at second iteration.
1771                          * More elegant solution is required!!!
1772                          *
1773                          * Look: we have the following (pseudo)queues:
1774                          *
1775                          * 1. packets in flight
1776                          * 2. backlog
1777                          * 3. prequeue
1778                          * 4. receive_queue
1779                          *
1780                          * Each queue can be processed only if the next ones
1781                          * are empty. At this point we have empty receive_queue.
1782                          * But prequeue _can_ be not empty after 2nd iteration,
1783                          * when we jumped to start of loop because backlog
1784                          * processing added something to receive_queue.
1785                          * We cannot release_sock(), because backlog contains
1786                          * packets arrived _after_ prequeued ones.
1787                          *
1788                          * Shortly, algorithm is clear --- to process all
1789                          * the queues in order. We could make it more directly,
1790                          * requeueing packets from backlog to prequeue, if
1791                          * is not empty. It is more elegant, but eats cycles,
1792                          * unfortunately.
1793                          */
1794                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1795                                 goto do_prequeue;
1796 
1797                         /* __ Set realtime policy in scheduler __ */
1798                 }
1799 
1800                 if (copied >= target) {
1801                         /* Do not sleep, just process backlog. */
1802                         release_sock(sk);
1803                         lock_sock(sk);
1804                 } else {
1805                         sk_wait_data(sk, &timeo, last);
1806                 }
1807 
1808                 if (user_recv) {
1809                         int chunk;
1810 
1811                         /* __ Restore normal policy in scheduler __ */
1812 
1813                         chunk = len - tp->ucopy.len;
1814                         if (chunk != 0) {
1815                                 NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1816                                 len -= chunk;
1817                                 copied += chunk;
1818                         }
1819 
1820                         if (tp->rcv_nxt == tp->copied_seq &&
1821                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1822 do_prequeue:
1823                                 tcp_prequeue_process(sk);
1824 
1825                                 chunk = len - tp->ucopy.len;
1826                                 if (chunk != 0) {
1827                                         NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1828                                         len -= chunk;
1829                                         copied += chunk;
1830                                 }
1831                         }
1832                 }
1833                 if ((flags & MSG_PEEK) &&
1834                     (peek_seq - copied - urg_hole != tp->copied_seq)) {
1835                         net_dbg_ratelimited("TCP(%s:%d): Application bug, race in MSG_PEEK\n",
1836                                             current->comm,
1837                                             task_pid_nr(current));
1838                         peek_seq = tp->copied_seq;
1839                 }
1840                 continue;
1841 
1842         found_ok_skb:
1843                 /* Ok so how much can we use? */
1844                 used = skb->len - offset;
1845                 if (len < used)
1846                         used = len;
1847 
1848                 /* Do we have urgent data here? */
1849                 if (tp->urg_data) {
1850                         u32 urg_offset = tp->urg_seq - *seq;
1851                         if (urg_offset < used) {
1852                                 if (!urg_offset) {
1853                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1854                                                 ++*seq;
1855                                                 urg_hole++;
1856                                                 offset++;
1857                                                 used--;
1858                                                 if (!used)
1859                                                         goto skip_copy;
1860                                         }
1861                                 } else
1862                                         used = urg_offset;
1863                         }
1864                 }
1865 
1866                 if (!(flags & MSG_TRUNC)) {
1867                         err = skb_copy_datagram_msg(skb, offset, msg, used);
1868                         if (err) {
1869                                 /* Exception. Bailout! */
1870                                 if (!copied)
1871                                         copied = -EFAULT;
1872                                 break;
1873                         }
1874                 }
1875 
1876                 *seq += used;
1877                 copied += used;
1878                 len -= used;
1879 
1880                 tcp_rcv_space_adjust(sk);
1881 
1882 skip_copy:
1883                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1884                         tp->urg_data = 0;
1885                         tcp_fast_path_check(sk);
1886                 }
1887                 if (used + offset < skb->len)
1888                         continue;
1889 
1890                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
1891                         goto found_fin_ok;
1892                 if (!(flags & MSG_PEEK))
1893                         sk_eat_skb(sk, skb);
1894                 continue;
1895 
1896         found_fin_ok:
1897                 /* Process the FIN. */
1898                 ++*seq;
1899                 if (!(flags & MSG_PEEK))
1900                         sk_eat_skb(sk, skb);
1901                 break;
1902         } while (len > 0);
1903 
1904         if (user_recv) {
1905                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1906                         int chunk;
1907 
1908                         tp->ucopy.len = copied > 0 ? len : 0;
1909 
1910                         tcp_prequeue_process(sk);
1911 
1912                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1913                                 NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1914                                 len -= chunk;
1915                                 copied += chunk;
1916                         }
1917                 }
1918 
1919                 tp->ucopy.task = NULL;
1920                 tp->ucopy.len = 0;
1921         }
1922 
1923         /* According to UNIX98, msg_name/msg_namelen are ignored
1924          * on connected socket. I was just happy when found this 8) --ANK
1925          */
1926 
1927         /* Clean up data we have read: This will do ACK frames. */
1928         tcp_cleanup_rbuf(sk, copied);
1929 
1930         release_sock(sk);
1931         return copied;
1932 
1933 out:
1934         release_sock(sk);
1935         return err;
1936 
1937 recv_urg:
1938         err = tcp_recv_urg(sk, msg, len, flags);
1939         goto out;
1940 
1941 recv_sndq:
1942         err = tcp_peek_sndq(sk, msg, len);
1943         goto out;
1944 }
1945 EXPORT_SYMBOL(tcp_recvmsg);
1946 
1947 void tcp_set_state(struct sock *sk, int state)
1948 {
1949         int oldstate = sk->sk_state;
1950 
1951         switch (state) {
1952         case TCP_ESTABLISHED:
1953                 if (oldstate != TCP_ESTABLISHED)
1954                         TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1955                 break;
1956 
1957         case TCP_CLOSE:
1958                 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1959                         TCP_INC_STATS(sock_net(sk), TCP_MIB_ESTABRESETS);
1960 
1961                 sk->sk_prot->unhash(sk);
1962                 if (inet_csk(sk)->icsk_bind_hash &&
1963                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1964                         inet_put_port(sk);
1965                 /* fall through */
1966         default:
1967                 if (oldstate == TCP_ESTABLISHED)
1968                         TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
1969         }
1970 
1971         /* Change state AFTER socket is unhashed to avoid closed
1972          * socket sitting in hash tables.
1973          */
1974         sk_state_store(sk, state);
1975 
1976 #ifdef STATE_TRACE
1977         SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
1978 #endif
1979 }
1980 EXPORT_SYMBOL_GPL(tcp_set_state);
1981 
1982 /*
1983  *      State processing on a close. This implements the state shift for
1984  *      sending our FIN frame. Note that we only send a FIN for some
1985  *      states. A shutdown() may have already sent the FIN, or we may be
1986  *      closed.
1987  */
1988 
1989 static const unsigned char new_state[16] = {
1990   /* current state:        new state:      action:      */
1991   [0 /* (Invalid) */]   = TCP_CLOSE,
1992   [TCP_ESTABLISHED]     = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1993   [TCP_SYN_SENT]        = TCP_CLOSE,
1994   [TCP_SYN_RECV]        = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1995   [TCP_FIN_WAIT1]       = TCP_FIN_WAIT1,
1996   [TCP_FIN_WAIT2]       = TCP_FIN_WAIT2,
1997   [TCP_TIME_WAIT]       = TCP_CLOSE,
1998   [TCP_CLOSE]           = TCP_CLOSE,
1999   [TCP_CLOSE_WAIT]      = TCP_LAST_ACK  | TCP_ACTION_FIN,
2000   [TCP_LAST_ACK]        = TCP_LAST_ACK,
2001   [TCP_LISTEN]          = TCP_CLOSE,
2002   [TCP_CLOSING]         = TCP_CLOSING,
2003   [TCP_NEW_SYN_RECV]    = TCP_CLOSE,    /* should not happen ! */
2004 };
2005 
2006 static int tcp_close_state(struct sock *sk)
2007 {
2008         int next = (int)new_state[sk->sk_state];
2009         int ns = next & TCP_STATE_MASK;
2010 
2011         tcp_set_state(sk, ns);
2012 
2013         return next & TCP_ACTION_FIN;
2014 }
2015 
2016 /*
2017  *      Shutdown the sending side of a connection. Much like close except
2018  *      that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
2019  */
2020 
2021 void tcp_shutdown(struct sock *sk, int how)
2022 {
2023         /*      We need to grab some memory, and put together a FIN,
2024          *      and then put it into the queue to be sent.
2025          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
2026          */
2027         if (!(how & SEND_SHUTDOWN))
2028                 return;
2029 
2030         /* If we've already sent a FIN, or it's a closed state, skip this. */
2031         if ((1 << sk->sk_state) &
2032             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
2033              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
2034                 /* Clear out any half completed packets.  FIN if needed. */
2035                 if (tcp_close_state(sk))
2036                         tcp_send_fin(sk);
2037         }
2038 }
2039 EXPORT_SYMBOL(tcp_shutdown);
2040 
2041 bool tcp_check_oom(struct sock *sk, int shift)
2042 {
2043         bool too_many_orphans, out_of_socket_memory;
2044 
2045         too_many_orphans = tcp_too_many_orphans(sk, shift);
2046         out_of_socket_memory = tcp_out_of_memory(sk);
2047 
2048         if (too_many_orphans)
2049                 net_info_ratelimited("too many orphaned sockets\n");
2050         if (out_of_socket_memory)
2051                 net_info_ratelimited("out of memory -- consider tuning tcp_mem\n");
2052         return too_many_orphans || out_of_socket_memory;
2053 }
2054 
2055 void tcp_close(struct sock *sk, long timeout)
2056 {
2057         struct sk_buff *skb;
2058         int data_was_unread = 0;
2059         int state;
2060 
2061         lock_sock(sk);
2062         sk->sk_shutdown = SHUTDOWN_MASK;
2063 
2064         if (sk->sk_state == TCP_LISTEN) {
2065                 tcp_set_state(sk, TCP_CLOSE);
2066 
2067                 /* Special case. */
2068                 inet_csk_listen_stop(sk);
2069 
2070                 goto adjudge_to_death;
2071         }
2072 
2073         /*  We need to flush the recv. buffs.  We do this only on the
2074          *  descriptor close, not protocol-sourced closes, because the
2075          *  reader process may not have drained the data yet!
2076          */
2077         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
2078                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq;
2079 
2080                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
2081                         len--;
2082                 data_was_unread += len;
2083                 __kfree_skb(skb);
2084         }
2085 
2086         sk_mem_reclaim(sk);
2087 
2088         /* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
2089         if (sk->sk_state == TCP_CLOSE)
2090                 goto adjudge_to_death;
2091 
2092         /* As outlined in RFC 2525, section 2.17, we send a RST here because
2093          * data was lost. To witness the awful effects of the old behavior of
2094          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
2095          * GET in an FTP client, suspend the process, wait for the client to
2096          * advertise a zero window, then kill -9 the FTP client, wheee...
2097          * Note: timeout is always zero in such a case.
2098          */
2099         if (unlikely(tcp_sk(sk)->repair)) {
2100                 sk->sk_prot->disconnect(sk, 0);
2101         } else if (data_was_unread) {
2102                 /* Unread data was tossed, zap the connection. */
2103                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
2104                 tcp_set_state(sk, TCP_CLOSE);
2105                 tcp_send_active_reset(sk, sk->sk_allocation);
2106         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
2107                 /* Check zero linger _after_ checking for unread data. */
2108                 sk->sk_prot->disconnect(sk, 0);
2109                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
2110         } else if (tcp_close_state(sk)) {
2111                 /* We FIN if the application ate all the data before
2112                  * zapping the connection.
2113                  */
2114 
2115                 /* RED-PEN. Formally speaking, we have broken TCP state
2116                  * machine. State transitions:
2117                  *
2118                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
2119                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
2120                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
2121                  *
2122                  * are legal only when FIN has been sent (i.e. in window),
2123                  * rather than queued out of window. Purists blame.
2124                  *
2125                  * F.e. "RFC state" is ESTABLISHED,
2126                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
2127                  *
2128                  * The visible declinations are that sometimes
2129                  * we enter time-wait state, when it is not required really
2130                  * (harmless), do not send active resets, when they are
2131                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
2132                  * they look as CLOSING or LAST_ACK for Linux)
2133                  * Probably, I missed some more holelets.
2134                  *                                              --ANK
2135                  * XXX (TFO) - To start off we don't support SYN+ACK+FIN
2136                  * in a single packet! (May consider it later but will
2137                  * probably need API support or TCP_CORK SYN-ACK until
2138                  * data is written and socket is closed.)
2139                  */
2140                 tcp_send_fin(sk);
2141         }
2142 
2143         sk_stream_wait_close(sk, timeout);
2144 
2145 adjudge_to_death:
2146         state = sk->sk_state;
2147         sock_hold(sk);
2148         sock_orphan(sk);
2149 
2150         /* It is the last release_sock in its life. It will remove backlog. */
2151         release_sock(sk);
2152 
2153 
2154         /* Now socket is owned by kernel and we acquire BH lock
2155            to finish close. No need to check for user refs.
2156          */
2157         local_bh_disable();
2158         bh_lock_sock(sk);
2159         WARN_ON(sock_owned_by_user(sk));
2160 
2161         percpu_counter_inc(sk->sk_prot->orphan_count);
2162 
2163         /* Have we already been destroyed by a softirq or backlog? */
2164         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
2165                 goto out;
2166 
2167         /*      This is a (useful) BSD violating of the RFC. There is a
2168          *      problem with TCP as specified in that the other end could
2169          *      keep a socket open forever with no application left this end.
2170          *      We use a 1 minute timeout (about the same as BSD) then kill
2171          *      our end. If they send after that then tough - BUT: long enough
2172          *      that we won't make the old 4*rto = almost no time - whoops
2173          *      reset mistake.
2174          *
2175          *      Nope, it was not mistake. It is really desired behaviour
2176          *      f.e. on http servers, when such sockets are useless, but
2177          *      consume significant resources. Let's do it with special
2178          *      linger2 option.                                 --ANK
2179          */
2180 
2181         if (sk->sk_state == TCP_FIN_WAIT2) {
2182                 struct tcp_sock *tp = tcp_sk(sk);
2183                 if (tp->linger2 < 0) {
2184                         tcp_set_state(sk, TCP_CLOSE);
2185                         tcp_send_active_reset(sk, GFP_ATOMIC);
2186                         __NET_INC_STATS(sock_net(sk),
2187                                         LINUX_MIB_TCPABORTONLINGER);
2188                 } else {
2189                         const int tmo = tcp_fin_time(sk);
2190 
2191                         if (tmo > TCP_TIMEWAIT_LEN) {
2192                                 inet_csk_reset_keepalive_timer(sk,
2193                                                 tmo - TCP_TIMEWAIT_LEN);
2194                         } else {
2195                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
2196                                 goto out;
2197                         }
2198                 }
2199         }
2200         if (sk->sk_state != TCP_CLOSE) {
2201                 sk_mem_reclaim(sk);
2202                 if (tcp_check_oom(sk, 0)) {
2203                         tcp_set_state(sk, TCP_CLOSE);
2204                         tcp_send_active_reset(sk, GFP_ATOMIC);
2205                         __NET_INC_STATS(sock_net(sk),
2206                                         LINUX_MIB_TCPABORTONMEMORY);
2207                 }
2208         }
2209 
2210         if (sk->sk_state == TCP_CLOSE) {
2211                 struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
2212                 /* We could get here with a non-NULL req if the socket is
2213                  * aborted (e.g., closed with unread data) before 3WHS
2214                  * finishes.
2215                  */
2216                 if (req)
2217                         reqsk_fastopen_remove(sk, req, false);
2218                 inet_csk_destroy_sock(sk);
2219         }
2220         /* Otherwise, socket is reprieved until protocol close. */
2221 
2222 out:
2223         bh_unlock_sock(sk);
2224         local_bh_enable();
2225         sock_put(sk);
2226 }
2227 EXPORT_SYMBOL(tcp_close);
2228 
2229 /* These states need RST on ABORT according to RFC793 */
2230 
2231 static inline bool tcp_need_reset(int state)
2232 {
2233         return (1 << state) &
2234                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
2235                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
2236 }
2237 
2238 int tcp_disconnect(struct sock *sk, int flags)
2239 {
2240         struct inet_sock *inet = inet_sk(sk);
2241         struct inet_connection_sock *icsk = inet_csk(sk);
2242         struct tcp_sock *tp = tcp_sk(sk);
2243         int err = 0;
2244         int old_state = sk->sk_state;
2245 
2246         if (old_state != TCP_CLOSE)
2247                 tcp_set_state(sk, TCP_CLOSE);
2248 
2249         /* ABORT function of RFC793 */
2250         if (old_state == TCP_LISTEN) {
2251                 inet_csk_listen_stop(sk);
2252         } else if (unlikely(tp->repair)) {
2253                 sk->sk_err = ECONNABORTED;
2254         } else if (tcp_need_reset(old_state) ||
2255                    (tp->snd_nxt != tp->write_seq &&
2256                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
2257                 /* The last check adjusts for discrepancy of Linux wrt. RFC
2258                  * states
2259                  */
2260                 tcp_send_active_reset(sk, gfp_any());
2261                 sk->sk_err = ECONNRESET;
2262         } else if (old_state == TCP_SYN_SENT)
2263                 sk->sk_err = ECONNRESET;
2264 
2265         tcp_clear_xmit_timers(sk);
2266         __skb_queue_purge(&sk->sk_receive_queue);
2267         tcp_write_queue_purge(sk);
2268         skb_rbtree_purge(&tp->out_of_order_queue);
2269 
2270         inet->inet_dport = 0;
2271 
2272         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
2273                 inet_reset_saddr(sk);
2274 
2275         sk->sk_shutdown = 0;
2276         sock_reset_flag(sk, SOCK_DONE);
2277         tp->srtt_us = 0;
2278         tp->write_seq += tp->max_window + 2;
2279         if (tp->write_seq == 0)
2280                 tp->write_seq = 1;
2281         icsk->icsk_backoff = 0;
2282         tp->snd_cwnd = 2;
2283         icsk->icsk_probes_out = 0;
2284         tp->packets_out = 0;
2285         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
2286         tp->snd_cwnd_cnt = 0;
2287         tp->window_clamp = 0;
2288         tcp_set_ca_state(sk, TCP_CA_Open);
2289         tcp_clear_retrans(tp);
2290         inet_csk_delack_init(sk);
2291         tcp_init_send_head(sk);
2292         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
2293         __sk_dst_reset(sk);
2294 
2295         WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
2296 
2297         sk->sk_error_report(sk);
2298         return err;
2299 }
2300 EXPORT_SYMBOL(tcp_disconnect);
2301 
2302 static inline bool tcp_can_repair_sock(const struct sock *sk)
2303 {
2304         return ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) &&
2305                 ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
2306 }
2307 
2308 static int tcp_repair_set_window(struct tcp_sock *tp, char __user *optbuf, int len)
2309 {
2310         struct tcp_repair_window opt;
2311 
2312         if (!tp->repair)
2313                 return -EPERM;
2314 
2315         if (len != sizeof(opt))
2316                 return -EINVAL;
2317 
2318         if (copy_from_user(&opt, optbuf, sizeof(opt)))
2319                 return -EFAULT;
2320 
2321         if (opt.max_window < opt.snd_wnd)
2322                 return -EINVAL;
2323 
2324         if (after(opt.snd_wl1, tp->rcv_nxt + opt.rcv_wnd))
2325                 return -EINVAL;
2326 
2327         if (after(opt.rcv_wup, tp->rcv_nxt))
2328                 return -EINVAL;
2329 
2330         tp->snd_wl1     = opt.snd_wl1;
2331         tp->snd_wnd     = opt.snd_wnd;
2332         tp->max_window  = opt.max_window;
2333 
2334         tp->rcv_wnd     = opt.rcv_wnd;
2335         tp->rcv_wup     = opt.rcv_wup;
2336 
2337         return 0;
2338 }
2339 
2340 static int tcp_repair_options_est(struct tcp_sock *tp,
2341                 struct tcp_repair_opt __user *optbuf, unsigned int len)
2342 {
2343         struct tcp_repair_opt opt;
2344 
2345         while (len >= sizeof(opt)) {
2346                 if (copy_from_user(&opt, optbuf, sizeof(opt)))
2347                         return -EFAULT;
2348 
2349                 optbuf++;
2350                 len -= sizeof(opt);
2351 
2352                 switch (opt.opt_code) {
2353                 case TCPOPT_MSS:
2354                         tp->rx_opt.mss_clamp = opt.opt_val;
2355                         break;
2356                 case TCPOPT_WINDOW:
2357                         {
2358                                 u16 snd_wscale = opt.opt_val & 0xFFFF;
2359                                 u16 rcv_wscale = opt.opt_val >> 16;
2360 
2361                                 if (snd_wscale > 14 || rcv_wscale > 14)
2362                                         return -EFBIG;
2363 
2364                                 tp->rx_opt.snd_wscale = snd_wscale;
2365                                 tp->rx_opt.rcv_wscale = rcv_wscale;
2366                                 tp->rx_opt.wscale_ok = 1;
2367                         }
2368                         break;
2369                 case TCPOPT_SACK_PERM:
2370                         if (opt.opt_val != 0)
2371                                 return -EINVAL;
2372 
2373                         tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
2374                         if (sysctl_tcp_fack)
2375                                 tcp_enable_fack(tp);
2376                         break;
2377                 case TCPOPT_TIMESTAMP:
2378                         if (opt.opt_val != 0)
2379                                 return -EINVAL;
2380 
2381                         tp->rx_opt.tstamp_ok = 1;
2382                         break;
2383                 }
2384         }
2385 
2386         return 0;
2387 }
2388 
2389 /*
2390  *      Socket option code for TCP.
2391  */
2392 static int do_tcp_setsockopt(struct sock *sk, int level,
2393                 int optname, char __user *optval, unsigned int optlen)
2394 {
2395         struct tcp_sock *tp = tcp_sk(sk);
2396         struct inet_connection_sock *icsk = inet_csk(sk);
2397         struct net *net = sock_net(sk);
2398         int val;
2399         int err = 0;
2400 
2401         /* These are data/string values, all the others are ints */
2402         switch (optname) {
2403         case TCP_CONGESTION: {
2404                 char name[TCP_CA_NAME_MAX];
2405 
2406                 if (optlen < 1)
2407                         return -EINVAL;
2408 
2409                 val = strncpy_from_user(name, optval,
2410                                         min_t(long, TCP_CA_NAME_MAX-1, optlen));
2411                 if (val < 0)
2412                         return -EFAULT;
2413                 name[val] = 0;
2414 
2415                 lock_sock(sk);
2416                 err = tcp_set_congestion_control(sk, name);
2417                 release_sock(sk);
2418                 return err;
2419         }
2420         default:
2421                 /* fallthru */
2422                 break;
2423         }
2424 
2425         if (optlen < sizeof(int))
2426                 return -EINVAL;
2427 
2428         if (get_user(val, (int __user *)optval))
2429                 return -EFAULT;
2430 
2431         lock_sock(sk);
2432 
2433         switch (optname) {
2434         case TCP_MAXSEG:
2435                 /* Values greater than interface MTU won't take effect. However
2436                  * at the point when this call is done we typically don't yet
2437                  * know which interface is going to be used */
2438                 if (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW) {
2439                         err = -EINVAL;
2440                         break;
2441                 }
2442                 tp->rx_opt.user_mss = val;
2443                 break;
2444 
2445         case TCP_NODELAY:
2446                 if (val) {
2447                         /* TCP_NODELAY is weaker than TCP_CORK, so that
2448                          * this option on corked socket is remembered, but
2449                          * it is not activated until cork is cleared.
2450                          *
2451                          * However, when TCP_NODELAY is set we make
2452                          * an explicit push, which overrides even TCP_CORK
2453                          * for currently queued segments.
2454                          */
2455                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
2456                         tcp_push_pending_frames(sk);
2457                 } else {
2458                         tp->nonagle &= ~TCP_NAGLE_OFF;
2459                 }
2460                 break;
2461 
2462         case TCP_THIN_LINEAR_TIMEOUTS:
2463                 if (val < 0 || val > 1)
2464                         err = -EINVAL;
2465                 else
2466                         tp->thin_lto = val;
2467                 break;
2468 
2469         case TCP_THIN_DUPACK:
2470                 if (val < 0 || val > 1)
2471                         err = -EINVAL;
2472                 else {
2473                         tp->thin_dupack = val;
2474                         if (tp->thin_dupack)
2475                                 tcp_disable_early_retrans(tp);
2476                 }
2477                 break;
2478 
2479         case TCP_REPAIR:
2480                 if (!tcp_can_repair_sock(sk))
2481                         err = -EPERM;
2482                 else if (val == 1) {
2483                         tp->repair = 1;
2484                         sk->sk_reuse = SK_FORCE_REUSE;
2485                         tp->repair_queue = TCP_NO_QUEUE;
2486                 } else if (val == 0) {
2487                         tp->repair = 0;
2488                         sk->sk_reuse = SK_NO_REUSE;
2489                         tcp_send_window_probe(sk);
2490                 } else
2491                         err = -EINVAL;
2492 
2493                 break;
2494 
2495         case TCP_REPAIR_QUEUE:
2496                 if (!tp->repair)
2497                         err = -EPERM;
2498                 else if (val < TCP_QUEUES_NR)
2499                         tp->repair_queue = val;
2500                 else
2501                         err = -EINVAL;
2502                 break;
2503 
2504         case TCP_QUEUE_SEQ:
2505                 if (sk->sk_state != TCP_CLOSE)
2506                         err = -EPERM;
2507                 else if (tp->repair_queue == TCP_SEND_QUEUE)
2508                         tp->write_seq = val;
2509                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2510                         tp->rcv_nxt = val;
2511                 else
2512                         err = -EINVAL;
2513                 break;
2514 
2515         case TCP_REPAIR_OPTIONS:
2516                 if (!tp->repair)
2517                         err = -EINVAL;
2518                 else if (sk->sk_state == TCP_ESTABLISHED)
2519                         err = tcp_repair_options_est(tp,
2520                                         (struct tcp_repair_opt __user *)optval,
2521                                         optlen);
2522                 else
2523                         err = -EPERM;
2524                 break;
2525 
2526         case TCP_CORK:
2527                 /* When set indicates to always queue non-full frames.
2528                  * Later the user clears this option and we transmit
2529                  * any pending partial frames in the queue.  This is
2530                  * meant to be used alongside sendfile() to get properly
2531                  * filled frames when the user (for example) must write
2532                  * out headers with a write() call first and then use
2533                  * sendfile to send out the data parts.
2534                  *
2535                  * TCP_CORK can be set together with TCP_NODELAY and it is
2536                  * stronger than TCP_NODELAY.
2537                  */
2538                 if (val) {
2539                         tp->nonagle |= TCP_NAGLE_CORK;
2540                 } else {
2541                         tp->nonagle &= ~TCP_NAGLE_CORK;
2542                         if (tp->nonagle&TCP_NAGLE_OFF)
2543                                 tp->nonagle |= TCP_NAGLE_PUSH;
2544                         tcp_push_pending_frames(sk);
2545                 }
2546                 break;
2547 
2548         case TCP_KEEPIDLE:
2549                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
2550                         err = -EINVAL;
2551                 else {
2552                         tp->keepalive_time = val * HZ;
2553                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
2554                             !((1 << sk->sk_state) &
2555                               (TCPF_CLOSE | TCPF_LISTEN))) {
2556                                 u32 elapsed = keepalive_time_elapsed(tp);
2557                                 if (tp->keepalive_time > elapsed)
2558                                         elapsed = tp->keepalive_time - elapsed;
2559                                 else
2560                                         elapsed = 0;
2561                                 inet_csk_reset_keepalive_timer(sk, elapsed);
2562                         }
2563                 }
2564                 break;
2565         case TCP_KEEPINTVL:
2566                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
2567                         err = -EINVAL;
2568                 else
2569                         tp->keepalive_intvl = val * HZ;
2570                 break;
2571         case TCP_KEEPCNT:
2572                 if (val < 1 || val > MAX_TCP_KEEPCNT)
2573                         err = -EINVAL;
2574                 else
2575                         tp->keepalive_probes = val;
2576                 break;
2577         case TCP_SYNCNT:
2578                 if (val < 1 || val > MAX_TCP_SYNCNT)
2579                         err = -EINVAL;
2580                 else
2581                         icsk->icsk_syn_retries = val;
2582                 break;
2583 
2584         case TCP_SAVE_SYN:
2585                 if (val < 0 || val > 1)
2586                         err = -EINVAL;
2587                 else
2588                         tp->save_syn = val;
2589                 break;
2590 
2591         case TCP_LINGER2:
2592                 if (val < 0)
2593                         tp->linger2 = -1;
2594                 else if (val > net->ipv4.sysctl_tcp_fin_timeout / HZ)
2595                         tp->linger2 = 0;
2596                 else
2597                         tp->linger2 = val * HZ;
2598                 break;
2599 
2600         case TCP_DEFER_ACCEPT:
2601                 /* Translate value in seconds to number of retransmits */
2602                 icsk->icsk_accept_queue.rskq_defer_accept =
2603                         secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
2604                                         TCP_RTO_MAX / HZ);
2605                 break;
2606 
2607         case TCP_WINDOW_CLAMP:
2608                 if (!val) {
2609                         if (sk->sk_state != TCP_CLOSE) {
2610                                 err = -EINVAL;
2611                                 break;
2612                         }
2613                         tp->window_clamp = 0;
2614                 } else
2615                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
2616                                                 SOCK_MIN_RCVBUF / 2 : val;
2617                 break;
2618 
2619         case TCP_QUICKACK:
2620                 if (!val) {
2621                         icsk->icsk_ack.pingpong = 1;
2622                 } else {
2623                         icsk->icsk_ack.pingpong = 0;
2624                         if ((1 << sk->sk_state) &
2625                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
2626                             inet_csk_ack_scheduled(sk)) {
2627                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
2628                                 tcp_cleanup_rbuf(sk, 1);
2629                                 if (!(val & 1))
2630                                         icsk->icsk_ack.pingpong = 1;
2631                         }
2632                 }
2633                 break;
2634 
2635 #ifdef CONFIG_TCP_MD5SIG
2636         case TCP_MD5SIG:
2637                 /* Read the IP->Key mappings from userspace */
2638                 err = tp->af_specific->md5_parse(sk, optval, optlen);
2639                 break;
2640 #endif
2641         case TCP_USER_TIMEOUT:
2642                 /* Cap the max time in ms TCP will retry or probe the window
2643                  * before giving up and aborting (ETIMEDOUT) a connection.
2644                  */
2645                 if (val < 0)
2646                         err = -EINVAL;
2647                 else
2648                         icsk->icsk_user_timeout = msecs_to_jiffies(val);
2649                 break;
2650 
2651         case TCP_FASTOPEN:
2652                 if (val >= 0 && ((1 << sk->sk_state) & (TCPF_CLOSE |
2653                     TCPF_LISTEN))) {
2654                         tcp_fastopen_init_key_once(true);
2655 
2656                         fastopen_queue_tune(sk, val);
2657                 } else {
2658                         err = -EINVAL;
2659                 }
2660                 break;
2661         case TCP_TIMESTAMP:
2662                 if (!tp->repair)
2663                         err = -EPERM;
2664                 else
2665                         tp->tsoffset = val - tcp_time_stamp;
2666                 break;
2667         case TCP_REPAIR_WINDOW:
2668                 err = tcp_repair_set_window(tp, optval, optlen);
2669                 break;
2670         case TCP_NOTSENT_LOWAT:
2671                 tp->notsent_lowat = val;
2672                 sk->sk_write_space(sk);
2673                 break;
2674         default:
2675                 err = -ENOPROTOOPT;
2676                 break;
2677         }
2678 
2679         release_sock(sk);
2680         return err;
2681 }
2682 
2683 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
2684                    unsigned int optlen)
2685 {
2686         const struct inet_connection_sock *icsk = inet_csk(sk);
2687 
2688         if (level != SOL_TCP)
2689                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
2690                                                      optval, optlen);
2691         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2692 }
2693 EXPORT_SYMBOL(tcp_setsockopt);
2694 
2695 #ifdef CONFIG_COMPAT
2696 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
2697                           char __user *optval, unsigned int optlen)
2698 {
2699         if (level != SOL_TCP)
2700                 return inet_csk_compat_setsockopt(sk, level, optname,
2701                                                   optval, optlen);
2702         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
2703 }
2704 EXPORT_SYMBOL(compat_tcp_setsockopt);
2705 #endif
2706 
2707 /* Return information about state of tcp endpoint in API format. */
2708 void tcp_get_info(struct sock *sk, struct tcp_info *info)
2709 {
2710         const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
2711         const struct inet_connection_sock *icsk = inet_csk(sk);
2712         u32 now = tcp_time_stamp, intv;
2713         unsigned int start;
2714         int notsent_bytes;
2715         u64 rate64;
2716         u32 rate;
2717 
2718         memset(info, 0, sizeof(*info));
2719         if (sk->sk_type != SOCK_STREAM)
2720                 return;
2721 
2722         info->tcpi_state = sk_state_load(sk);
2723 
2724         info->tcpi_ca_state = icsk->icsk_ca_state;
2725         info->tcpi_retransmits = icsk->icsk_retransmits;
2726         info->tcpi_probes = icsk->icsk_probes_out;
2727         info->tcpi_backoff = icsk->icsk_backoff;
2728 
2729         if (tp->rx_opt.tstamp_ok)
2730                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2731         if (tcp_is_sack(tp))
2732                 info->tcpi_options |= TCPI_OPT_SACK;
2733         if (tp->rx_opt.wscale_ok) {
2734                 info->tcpi_options |= TCPI_OPT_WSCALE;
2735                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2736                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2737         }
2738 
2739         if (tp->ecn_flags & TCP_ECN_OK)
2740                 info->tcpi_options |= TCPI_OPT_ECN;
2741         if (tp->ecn_flags & TCP_ECN_SEEN)
2742                 info->tcpi_options |= TCPI_OPT_ECN_SEEN;
2743         if (tp->syn_data_acked)
2744                 info->tcpi_options |= TCPI_OPT_SYN_DATA;
2745 
2746         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2747         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2748         info->tcpi_snd_mss = tp->mss_cache;
2749         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2750 
2751         if (info->tcpi_state == TCP_LISTEN) {
2752                 info->tcpi_unacked = sk->sk_ack_backlog;
2753                 info->tcpi_sacked = sk->sk_max_ack_backlog;
2754         } else {
2755                 info->tcpi_unacked = tp->packets_out;
2756                 info->tcpi_sacked = tp->sacked_out;
2757         }
2758         info->tcpi_lost = tp->lost_out;
2759         info->tcpi_retrans = tp->retrans_out;
2760         info->tcpi_fackets = tp->fackets_out;
2761 
2762         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2763         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2764         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2765 
2766         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2767         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2768         info->tcpi_rtt = tp->srtt_us >> 3;
2769         info->tcpi_rttvar = tp->mdev_us >> 2;
2770         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2771         info->tcpi_snd_cwnd = tp->snd_cwnd;
2772         info->tcpi_advmss = tp->advmss;
2773         info->tcpi_reordering = tp->reordering;
2774 
2775         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2776         info->tcpi_rcv_space = tp->rcvq_space.space;
2777 
2778         info->tcpi_total_retrans = tp->total_retrans;
2779 
2780         rate = READ_ONCE(sk->sk_pacing_rate);
2781         rate64 = rate != ~0U ? rate : ~0ULL;
2782         put_unaligned(rate64, &info->tcpi_pacing_rate);
2783 
2784         rate = READ_ONCE(sk->sk_max_pacing_rate);
2785         rate64 = rate != ~0U ? rate : ~0ULL;
2786         put_unaligned(rate64, &info->tcpi_max_pacing_rate);
2787 
2788         do {
2789                 start = u64_stats_fetch_begin_irq(&tp->syncp);
2790                 put_unaligned(tp->bytes_acked, &info->tcpi_bytes_acked);
2791                 put_unaligned(tp->bytes_received, &info->tcpi_bytes_received);
2792         } while (u64_stats_fetch_retry_irq(&tp->syncp, start));
2793         info->tcpi_segs_out = tp->segs_out;
2794         info->tcpi_segs_in = tp->segs_in;
2795 
2796         notsent_bytes = READ_ONCE(tp->write_seq) - READ_ONCE(tp->snd_nxt);
2797         info->tcpi_notsent_bytes = max(0, notsent_bytes);
2798 
2799         info->tcpi_min_rtt = tcp_min_rtt(tp);
2800         info->tcpi_data_segs_in = tp->data_segs_in;
2801         info->tcpi_data_segs_out = tp->data_segs_out;
2802 
2803         info->tcpi_delivery_rate_app_limited = tp->rate_app_limited ? 1 : 0;
2804         rate = READ_ONCE(tp->rate_delivered);
2805         intv = READ_ONCE(tp->rate_interval_us);
2806         if (rate && intv) {
2807                 rate64 = (u64)rate * tp->mss_cache * USEC_PER_SEC;
2808                 do_div(rate64, intv);
2809                 put_unaligned(rate64, &info->tcpi_delivery_rate);
2810         }
2811 }
2812 EXPORT_SYMBOL_GPL(tcp_get_info);
2813 
2814 static int do_tcp_getsockopt(struct sock *sk, int level,
2815                 int optname, char __user *optval, int __user *optlen)
2816 {
2817         struct inet_connection_sock *icsk = inet_csk(sk);
2818         struct tcp_sock *tp = tcp_sk(sk);
2819         struct net *net = sock_net(sk);
2820         int val, len;
2821 
2822         if (get_user(len, optlen))
2823                 return -EFAULT;
2824 
2825         len = min_t(unsigned int, len, sizeof(int));
2826 
2827         if (len < 0)
2828                 return -EINVAL;
2829 
2830         switch (optname) {
2831         case TCP_MAXSEG:
2832                 val = tp->mss_cache;
2833                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2834                         val = tp->rx_opt.user_mss;
2835                 if (tp->repair)
2836                         val = tp->rx_opt.mss_clamp;
2837                 break;
2838         case TCP_NODELAY:
2839                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2840                 break;
2841         case TCP_CORK:
2842                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2843                 break;
2844         case TCP_KEEPIDLE:
2845                 val = keepalive_time_when(tp) / HZ;
2846                 break;
2847         case TCP_KEEPINTVL:
2848                 val = keepalive_intvl_when(tp) / HZ;
2849                 break;
2850         case TCP_KEEPCNT:
2851                 val = keepalive_probes(tp);
2852                 break;
2853         case TCP_SYNCNT:
2854                 val = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
2855                 break;
2856         case TCP_LINGER2:
2857                 val = tp->linger2;
2858                 if (val >= 0)
2859                         val = (val ? : net->ipv4.sysctl_tcp_fin_timeout) / HZ;
2860                 break;
2861         case TCP_DEFER_ACCEPT:
2862                 val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
2863                                       TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
2864                 break;
2865         case TCP_WINDOW_CLAMP:
2866                 val = tp->window_clamp;
2867                 break;
2868         case TCP_INFO: {
2869                 struct tcp_info info;
2870 
2871                 if (get_user(len, optlen))
2872                         return -EFAULT;
2873 
2874                 tcp_get_info(sk, &info);
2875 
2876                 len = min_t(unsigned int, len, sizeof(info));
2877                 if (put_user(len, optlen))
2878                         return -EFAULT;
2879                 if (copy_to_user(optval, &info, len))
2880                         return -EFAULT;
2881                 return 0;
2882         }
2883         case TCP_CC_INFO: {
2884                 const struct tcp_congestion_ops *ca_ops;
2885                 union tcp_cc_info info;
2886                 size_t sz = 0;
2887                 int attr;
2888 
2889                 if (get_user(len, optlen))
2890                         return -EFAULT;
2891 
2892                 ca_ops = icsk->icsk_ca_ops;
2893                 if (ca_ops && ca_ops->get_info)
2894                         sz = ca_ops->get_info(sk, ~0U, &attr, &info);
2895 
2896                 len = min_t(unsigned int, len, sz);
2897                 if (put_user(len, optlen))
2898                         return -EFAULT;
2899                 if (copy_to_user(optval, &info, len))
2900                         return -EFAULT;
2901                 return 0;
2902         }
2903         case TCP_QUICKACK:
2904                 val = !icsk->icsk_ack.pingpong;
2905                 break;
2906 
2907         case TCP_CONGESTION:
2908                 if (get_user(len, optlen))
2909                         return -EFAULT;
2910                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2911                 if (put_user(len, optlen))
2912                         return -EFAULT;
2913                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2914                         return -EFAULT;
2915                 return 0;
2916 
2917         case TCP_THIN_LINEAR_TIMEOUTS:
2918                 val = tp->thin_lto;
2919                 break;
2920         case TCP_THIN_DUPACK:
2921                 val = tp->thin_dupack;
2922                 break;
2923 
2924         case TCP_REPAIR:
2925                 val = tp->repair;
2926                 break;
2927 
2928         case TCP_REPAIR_QUEUE:
2929                 if (tp->repair)
2930                         val = tp->repair_queue;
2931                 else
2932                         return -EINVAL;
2933                 break;
2934 
2935         case TCP_REPAIR_WINDOW: {
2936                 struct tcp_repair_window opt;
2937 
2938                 if (get_user(len, optlen))
2939                         return -EFAULT;
2940 
2941                 if (len != sizeof(opt))
2942                         return -EINVAL;
2943 
2944                 if (!tp->repair)
2945                         return -EPERM;
2946 
2947                 opt.snd_wl1     = tp->snd_wl1;
2948                 opt.snd_wnd     = tp->snd_wnd;
2949                 opt.max_window  = tp->max_window;
2950                 opt.rcv_wnd     = tp->rcv_wnd;
2951                 opt.rcv_wup     = tp->rcv_wup;
2952 
2953                 if (copy_to_user(optval, &opt, len))
2954                         return -EFAULT;
2955                 return 0;
2956         }
2957         case TCP_QUEUE_SEQ:
2958                 if (tp->repair_queue == TCP_SEND_QUEUE)
2959                         val = tp->write_seq;
2960                 else if (tp->repair_queue == TCP_RECV_QUEUE)
2961                         val = tp->rcv_nxt;
2962                 else
2963                         return -EINVAL;
2964                 break;
2965 
2966         case TCP_USER_TIMEOUT:
2967                 val = jiffies_to_msecs(icsk->icsk_user_timeout);
2968                 break;
2969 
2970         case TCP_FASTOPEN:
2971                 val = icsk->icsk_accept_queue.fastopenq.max_qlen;
2972                 break;
2973 
2974         case TCP_TIMESTAMP:
2975                 val = tcp_time_stamp + tp->tsoffset;
2976                 break;
2977         case TCP_NOTSENT_LOWAT:
2978                 val = tp->notsent_lowat;
2979                 break;
2980         case TCP_SAVE_SYN:
2981                 val = tp->save_syn;
2982                 break;
2983         case TCP_SAVED_SYN: {
2984                 if (get_user(len, optlen))
2985                         return -EFAULT;
2986 
2987                 lock_sock(sk);
2988                 if (tp->saved_syn) {
2989                         if (len < tp->saved_syn[0]) {
2990                                 if (put_user(tp->saved_syn[0], optlen)) {
2991                                         release_sock(sk);
2992                                         return -EFAULT;
2993                                 }
2994                                 release_sock(sk);
2995                                 return -EINVAL;
2996                         }
2997                         len = tp->saved_syn[0];
2998                         if (put_user(len, optlen)) {
2999                                 release_sock(sk);
3000                                 return -EFAULT;
3001                         }
3002                         if (copy_to_user(optval, tp->saved_syn + 1, len)) {
3003                                 release_sock(sk);
3004                                 return -EFAULT;
3005                         }
3006                         tcp_saved_syn_free(tp);
3007                         release_sock(sk);
3008                 } else {
3009                         release_sock(sk);
3010                         len = 0;
3011                         if (put_user(len, optlen))
3012                                 return -EFAULT;
3013                 }
3014                 return 0;
3015         }
3016         default:
3017                 return -ENOPROTOOPT;
3018         }
3019 
3020         if (put_user(len, optlen))
3021                 return -EFAULT;
3022         if (copy_to_user(optval, &val, len))
3023                 return -EFAULT;
3024         return 0;
3025 }
3026 
3027 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
3028                    int __user *optlen)
3029 {
3030         struct inet_connection_sock *icsk = inet_csk(sk);
3031 
3032         if (level != SOL_TCP)
3033                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
3034                                                      optval, optlen);
3035         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
3036 }
3037 EXPORT_SYMBOL(tcp_getsockopt);
3038 
3039 #ifdef CONFIG_COMPAT
3040 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
3041                           char __user *optval, int __user *optlen)
3042 {
3043         if (level != SOL_TCP)
3044                 return inet_csk_compat_getsockopt(sk, level, optname,
3045                                                   optval, optlen);
3046         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
3047 }
3048 EXPORT_SYMBOL(compat_tcp_getsockopt);
3049 #endif
3050 
3051 #ifdef CONFIG_TCP_MD5SIG
3052 static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool);
3053 static DEFINE_MUTEX(tcp_md5sig_mutex);
3054 static bool tcp_md5sig_pool_populated = false;
3055 
3056 static void __tcp_alloc_md5sig_pool(void)
3057 {
3058         struct crypto_ahash *hash;
3059         int cpu;
3060 
3061         hash = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
3062         if (IS_ERR(hash))
3063                 return;
3064 
3065         for_each_possible_cpu(cpu) {
3066                 void *scratch = per_cpu(tcp_md5sig_pool, cpu).scratch;
3067                 struct ahash_request *req;
3068 
3069                 if (!scratch) {
3070                         scratch = kmalloc_node(sizeof(union tcp_md5sum_block) +
3071                                                sizeof(struct tcphdr),
3072                                                GFP_KERNEL,
3073                                                cpu_to_node(cpu));
3074                         if (!scratch)
3075                                 return;
3076                         per_cpu(tcp_md5sig_pool, cpu).scratch = scratch;
3077                 }
3078                 if (per_cpu(tcp_md5sig_pool, cpu).md5_req)
3079                         continue;
3080 
3081                 req = ahash_request_alloc(hash, GFP_KERNEL);
3082                 if (!req)
3083                         return;
3084 
3085                 ahash_request_set_callback(req, 0, NULL, NULL);
3086 
3087                 per_cpu(tcp_md5sig_pool, cpu).md5_req = req;
3088         }
3089         /* before setting tcp_md5sig_pool_populated, we must commit all writes
3090          * to memory. See smp_rmb() in tcp_get_md5sig_pool()
3091          */
3092         smp_wmb();
3093         tcp_md5sig_pool_populated = true;
3094 }
3095 
3096 bool tcp_alloc_md5sig_pool(void)
3097 {
3098         if (unlikely(!tcp_md5sig_pool_populated)) {
3099                 mutex_lock(&tcp_md5sig_mutex);
3100 
3101                 if (!tcp_md5sig_pool_populated)
3102                         __tcp_alloc_md5sig_pool();
3103 
3104                 mutex_unlock(&tcp_md5sig_mutex);
3105         }
3106         return tcp_md5sig_pool_populated;
3107 }
3108 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
3109 
3110 
3111 /**
3112  *      tcp_get_md5sig_pool - get md5sig_pool for this user
3113  *
3114  *      We use percpu structure, so if we succeed, we exit with preemption
3115  *      and BH disabled, to make sure another thread or softirq handling
3116  *      wont try to get same context.
3117  */
3118 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
3119 {
3120         local_bh_disable();
3121 
3122         if (tcp_md5sig_pool_populated) {
3123                 /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
3124                 smp_rmb();
3125                 return this_cpu_ptr(&tcp_md5sig_pool);
3126         }
3127         local_bh_enable();
3128         return NULL;
3129 }
3130 EXPORT_SYMBOL(tcp_get_md5sig_pool);
3131 
3132 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
3133                           const struct sk_buff *skb, unsigned int header_len)
3134 {
3135         struct scatterlist sg;
3136         const struct tcphdr *tp = tcp_hdr(skb);
3137         struct ahash_request *req = hp->md5_req;
3138         unsigned int i;
3139         const unsigned int head_data_len = skb_headlen(skb) > header_len ?
3140                                            skb_headlen(skb) - header_len : 0;
3141         const struct skb_shared_info *shi = skb_shinfo(skb);
3142         struct sk_buff *frag_iter;
3143 
3144         sg_init_table(&sg, 1);
3145 
3146         sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
3147         ahash_request_set_crypt(req, &sg, NULL, head_data_len);
3148         if (crypto_ahash_update(req))
3149                 return 1;
3150 
3151         for (i = 0; i < shi->nr_frags; ++i) {
3152                 const struct skb_frag_struct *f = &shi->frags[i];
3153                 unsigned int offset = f->page_offset;
3154                 struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
3155 
3156                 sg_set_page(&sg, page, skb_frag_size(f),
3157                             offset_in_page(offset));
3158                 ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(f));
3159                 if (crypto_ahash_update(req))
3160                         return 1;
3161         }
3162 
3163         skb_walk_frags(skb, frag_iter)
3164                 if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
3165                         return 1;
3166 
3167         return 0;
3168 }
3169 EXPORT_SYMBOL(tcp_md5_hash_skb_data);
3170 
3171 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key)
3172 {
3173         struct scatterlist sg;
3174 
3175         sg_init_one(&sg, key->key, key->keylen);
3176         ahash_request_set_crypt(hp->md5_req, &sg, NULL, key->keylen);
3177         return crypto_ahash_update(hp->md5_req);
3178 }
3179 EXPORT_SYMBOL(tcp_md5_hash_key);
3180 
3181 #endif
3182 
3183 void tcp_done(struct sock *sk)
3184 {
3185         struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
3186 
3187         if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
3188                 TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
3189 
3190         tcp_set_state(sk, TCP_CLOSE);
3191         tcp_clear_xmit_timers(sk);
3192         if (req)
3193                 reqsk_fastopen_remove(sk, req, false);
3194 
3195         sk->sk_shutdown = SHUTDOWN_MASK;
3196 
3197         if (!sock_flag(sk, SOCK_DEAD))
3198                 sk->sk_state_change(sk);
3199         else
3200                 inet_csk_destroy_sock(sk);
3201 }
3202 EXPORT_SYMBOL_GPL(tcp_done);
3203 
3204 int tcp_abort(struct sock *sk, int err)
3205 {
3206         if (!sk_fullsock(sk)) {
3207                 if (sk->sk_state == TCP_NEW_SYN_RECV) {
3208                         struct request_sock *req = inet_reqsk(sk);
3209 
3210                         local_bh_disable();
3211                         inet_csk_reqsk_queue_drop_and_put(req->rsk_listener,
3212                                                           req);
3213                         local_bh_enable();
3214                         return 0;
3215                 }
3216                 return -EOPNOTSUPP;
3217         }
3218 
3219         /* Don't race with userspace socket closes such as tcp_close. */
3220         lock_sock(sk);
3221 
3222         if (sk->sk_state == TCP_LISTEN) {
3223                 tcp_set_state(sk, TCP_CLOSE);
3224                 inet_csk_listen_stop(sk);
3225         }
3226 
3227         /* Don't race with BH socket closes such as inet_csk_listen_stop. */
3228         local_bh_disable();
3229         bh_lock_sock(sk);
3230 
3231         if (!sock_flag(sk, SOCK_DEAD)) {
3232                 sk->sk_err = err;
3233                 /* This barrier is coupled with smp_rmb() in tcp_poll() */
3234                 smp_wmb();
3235                 sk->sk_error_report(sk);
3236                 if (tcp_need_reset(sk->sk_state))
3237                         tcp_send_active_reset(sk, GFP_ATOMIC);
3238                 tcp_done(sk);
3239         }
3240 
3241         bh_unlock_sock(sk);
3242         local_bh_enable();
3243         release_sock(sk);
3244         return 0;
3245 }
3246 EXPORT_SYMBOL_GPL(tcp_abort);
3247 
3248 extern struct tcp_congestion_ops tcp_reno;
3249 
3250 static __initdata unsigned long thash_entries;
3251 static int __init set_thash_entries(char *str)
3252 {
3253         ssize_t ret;
3254 
3255         if (!str)
3256                 return 0;
3257 
3258         ret = kstrtoul(str, 0, &thash_entries);
3259         if (ret)
3260                 return 0;
3261 
3262         return 1;
3263 }
3264 __setup("thash_entries=", set_thash_entries);
3265 
3266 static void __init tcp_init_mem(void)
3267 {
3268         unsigned long limit = nr_free_buffer_pages() / 16;
3269 
3270         limit = max(limit, 128UL);
3271         sysctl_tcp_mem[0] = limit / 4 * 3;              /* 4.68 % */
3272         sysctl_tcp_mem[1] = limit;                      /* 6.25 % */
3273         sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;      /* 9.37 % */
3274 }
3275 
3276 void __init tcp_init(void)
3277 {
3278         int max_rshare, max_wshare, cnt;
3279         unsigned long limit;
3280         unsigned int i;
3281 
3282         BUILD_BUG_ON(sizeof(struct tcp_skb_cb) >
3283                      FIELD_SIZEOF(struct sk_buff, cb));
3284 
3285         percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
3286         percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL);
3287         tcp_hashinfo.bind_bucket_cachep =
3288                 kmem_cache_create("tcp_bind_bucket",
3289                                   sizeof(struct inet_bind_bucket), 0,
3290                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3291 
3292         /* Size and allocate the main established and bind bucket
3293          * hash tables.
3294          *
3295          * The methodology is similar to that of the buffer cache.
3296          */
3297         tcp_hashinfo.ehash =
3298                 alloc_large_system_hash("TCP established",
3299                                         sizeof(struct inet_ehash_bucket),
3300                                         thash_entries,
3301                                         17, /* one slot per 128 KB of memory */
3302                                         0,
3303                                         NULL,
3304                                         &tcp_hashinfo.ehash_mask,
3305                                         0,
3306                                         thash_entries ? 0 : 512 * 1024);
3307         for (i = 0; i <= tcp_hashinfo.ehash_mask; i++)
3308                 INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
3309 
3310         if (inet_ehash_locks_alloc(&tcp_hashinfo))
3311                 panic("TCP: failed to alloc ehash_locks");
3312         tcp_hashinfo.bhash =
3313                 alloc_large_system_hash("TCP bind",
3314                                         sizeof(struct inet_bind_hashbucket),
3315                                         tcp_hashinfo.ehash_mask + 1,
3316                                         17, /* one slot per 128 KB of memory */
3317                                         0,
3318                                         &tcp_hashinfo.bhash_size,
3319                                         NULL,
3320                                         0,
3321                                         64 * 1024);
3322         tcp_hashinfo.bhash_size = 1U << tcp_hashinfo.bhash_size;
3323         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
3324                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
3325                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
3326         }
3327 
3328 
3329         cnt = tcp_hashinfo.ehash_mask + 1;
3330 
3331         tcp_death_row.sysctl_max_tw_buckets = cnt / 2;
3332         sysctl_tcp_max_orphans = cnt / 2;
3333         sysctl_max_syn_backlog = max(128, cnt / 256);
3334 
3335         tcp_init_mem();
3336         /* Set per-socket limits to no more than 1/128 the pressure threshold */
3337         limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
3338         max_wshare = min(4UL*1024*1024, limit);
3339         max_rshare = min(6UL*1024*1024, limit);
3340 
3341         sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
3342         sysctl_tcp_wmem[1] = 16*1024;
3343         sysctl_tcp_wmem[2] = max(64*1024, max_wshare);
3344 
3345         sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
3346         sysctl_tcp_rmem[1] = 87380;
3347         sysctl_tcp_rmem[2] = max(87380, max_rshare);
3348 
3349         pr_info("Hash tables configured (established %u bind %u)\n",
3350                 tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
3351 
3352         tcp_metrics_init();
3353         BUG_ON(tcp_register_congestion_control(&tcp_reno) != 0);
3354         tcp_tasklet_init();
3355 }
3356 

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