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21#include <linux/module.h>
22#include <linux/gfp.h>
23#include <net/tcp.h>
24
25
26
27
28
29
30
31
32static void tcp_write_err(struct sock *sk)
33{
34 sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
35 sk->sk_error_report(sk);
36
37 tcp_write_queue_purge(sk);
38 tcp_done(sk);
39 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT);
40}
41
42
43
44
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64
65
66static int tcp_out_of_resources(struct sock *sk, bool do_reset)
67{
68 struct tcp_sock *tp = tcp_sk(sk);
69 int shift = 0;
70
71
72
73 if ((s32)(tcp_jiffies32 - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset)
74 shift++;
75
76
77 if (sk->sk_err_soft)
78 shift++;
79
80 if (tcp_check_oom(sk, shift)) {
81
82
83 if ((s32)(tcp_jiffies32 - tp->lsndtime) <= TCP_TIMEWAIT_LEN ||
84
85 (!tp->snd_wnd && !tp->packets_out))
86 do_reset = true;
87 if (do_reset)
88 tcp_send_active_reset(sk, GFP_ATOMIC);
89 tcp_done(sk);
90 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);
91 return 1;
92 }
93
94 if (!check_net(sock_net(sk))) {
95
96 tcp_done(sk);
97 return 1;
98 }
99
100 return 0;
101}
102
103
104
105
106
107
108static int tcp_orphan_retries(struct sock *sk, bool alive)
109{
110 int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries;
111
112
113 if (sk->sk_err_soft && !alive)
114 retries = 0;
115
116
117
118
119 if (retries == 0 && alive)
120 retries = 8;
121 return retries;
122}
123
124static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
125{
126 const struct net *net = sock_net(sk);
127 int mss;
128
129
130 if (!net->ipv4.sysctl_tcp_mtu_probing)
131 return;
132
133 if (!icsk->icsk_mtup.enabled) {
134 icsk->icsk_mtup.enabled = 1;
135 icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
136 } else {
137 mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
138 mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
139 mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len);
140 icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
141 }
142 tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
143}
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159static bool retransmits_timed_out(struct sock *sk,
160 unsigned int boundary,
161 unsigned int timeout)
162{
163 const unsigned int rto_base = TCP_RTO_MIN;
164 unsigned int linear_backoff_thresh, start_ts;
165
166 if (!inet_csk(sk)->icsk_retransmits)
167 return false;
168
169 start_ts = tcp_sk(sk)->retrans_stamp;
170 if (unlikely(!start_ts)) {
171 struct sk_buff *head = tcp_rtx_queue_head(sk);
172
173 if (!head)
174 return false;
175 start_ts = tcp_skb_timestamp(head);
176 }
177
178 if (likely(timeout == 0)) {
179 linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base);
180
181 if (boundary <= linear_backoff_thresh)
182 timeout = ((2 << boundary) - 1) * rto_base;
183 else
184 timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
185 (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
186 }
187 return (tcp_time_stamp(tcp_sk(sk)) - start_ts) >= jiffies_to_msecs(timeout);
188}
189
190
191static int tcp_write_timeout(struct sock *sk)
192{
193 struct inet_connection_sock *icsk = inet_csk(sk);
194 struct tcp_sock *tp = tcp_sk(sk);
195 struct net *net = sock_net(sk);
196 bool expired, do_reset;
197 int retry_until;
198
199 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
200 if (icsk->icsk_retransmits) {
201 dst_negative_advice(sk);
202 } else if (!tp->syn_data && !tp->syn_fastopen) {
203 sk_rethink_txhash(sk);
204 }
205 retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
206 expired = icsk->icsk_retransmits >= retry_until;
207 } else {
208 if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0)) {
209
210 tcp_mtu_probing(icsk, sk);
211
212 dst_negative_advice(sk);
213 } else {
214 sk_rethink_txhash(sk);
215 }
216
217 retry_until = net->ipv4.sysctl_tcp_retries2;
218 if (sock_flag(sk, SOCK_DEAD)) {
219 const bool alive = icsk->icsk_rto < TCP_RTO_MAX;
220
221 retry_until = tcp_orphan_retries(sk, alive);
222 do_reset = alive ||
223 !retransmits_timed_out(sk, retry_until, 0);
224
225 if (tcp_out_of_resources(sk, do_reset))
226 return 1;
227 }
228 expired = retransmits_timed_out(sk, retry_until,
229 icsk->icsk_user_timeout);
230 }
231 tcp_fastopen_active_detect_blackhole(sk, expired);
232
233 if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG))
234 tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB,
235 icsk->icsk_retransmits,
236 icsk->icsk_rto, (int)expired);
237
238 if (expired) {
239
240 tcp_write_err(sk);
241 return 1;
242 }
243
244 return 0;
245}
246
247
248void tcp_delack_timer_handler(struct sock *sk)
249{
250 struct inet_connection_sock *icsk = inet_csk(sk);
251
252 sk_mem_reclaim_partial(sk);
253
254 if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
255 !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
256 goto out;
257
258 if (time_after(icsk->icsk_ack.timeout, jiffies)) {
259 sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
260 goto out;
261 }
262 icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
263
264 if (inet_csk_ack_scheduled(sk)) {
265 if (!icsk->icsk_ack.pingpong) {
266
267 icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto);
268 } else {
269
270
271
272 icsk->icsk_ack.pingpong = 0;
273 icsk->icsk_ack.ato = TCP_ATO_MIN;
274 }
275 tcp_mstamp_refresh(tcp_sk(sk));
276 tcp_send_ack(sk);
277 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS);
278 }
279
280out:
281 if (tcp_under_memory_pressure(sk))
282 sk_mem_reclaim(sk);
283}
284
285
286
287
288
289
290
291
292
293
294
295static void tcp_delack_timer(struct timer_list *t)
296{
297 struct inet_connection_sock *icsk =
298 from_timer(icsk, t, icsk_delack_timer);
299 struct sock *sk = &icsk->icsk_inet.sk;
300
301 bh_lock_sock(sk);
302 if (!sock_owned_by_user(sk)) {
303 tcp_delack_timer_handler(sk);
304 } else {
305 icsk->icsk_ack.blocked = 1;
306 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
307
308 if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags))
309 sock_hold(sk);
310 }
311 bh_unlock_sock(sk);
312 sock_put(sk);
313}
314
315static void tcp_probe_timer(struct sock *sk)
316{
317 struct inet_connection_sock *icsk = inet_csk(sk);
318 struct sk_buff *skb = tcp_send_head(sk);
319 struct tcp_sock *tp = tcp_sk(sk);
320 int max_probes;
321 u32 start_ts;
322
323 if (tp->packets_out || !skb) {
324 icsk->icsk_probes_out = 0;
325 return;
326 }
327
328
329
330
331
332
333
334
335
336 start_ts = tcp_skb_timestamp(skb);
337 if (!start_ts)
338 skb->skb_mstamp = tp->tcp_mstamp;
339 else if (icsk->icsk_user_timeout &&
340 (s32)(tcp_time_stamp(tp) - start_ts) >
341 jiffies_to_msecs(icsk->icsk_user_timeout))
342 goto abort;
343
344 max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2;
345 if (sock_flag(sk, SOCK_DEAD)) {
346 const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX;
347
348 max_probes = tcp_orphan_retries(sk, alive);
349 if (!alive && icsk->icsk_backoff >= max_probes)
350 goto abort;
351 if (tcp_out_of_resources(sk, true))
352 return;
353 }
354
355 if (icsk->icsk_probes_out > max_probes) {
356abort: tcp_write_err(sk);
357 } else {
358
359 tcp_send_probe0(sk);
360 }
361}
362
363
364
365
366
367static void tcp_fastopen_synack_timer(struct sock *sk)
368{
369 struct inet_connection_sock *icsk = inet_csk(sk);
370 int max_retries = icsk->icsk_syn_retries ? :
371 sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1;
372 struct request_sock *req;
373
374 req = tcp_sk(sk)->fastopen_rsk;
375 req->rsk_ops->syn_ack_timeout(req);
376
377 if (req->num_timeout >= max_retries) {
378 tcp_write_err(sk);
379 return;
380 }
381
382
383
384
385
386 inet_rtx_syn_ack(sk, req);
387 req->num_timeout++;
388 icsk->icsk_retransmits++;
389 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
390 TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
391}
392
393
394
395
396
397
398
399
400
401
402
403
404
405void tcp_retransmit_timer(struct sock *sk)
406{
407 struct tcp_sock *tp = tcp_sk(sk);
408 struct net *net = sock_net(sk);
409 struct inet_connection_sock *icsk = inet_csk(sk);
410
411 if (tp->fastopen_rsk) {
412 WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
413 sk->sk_state != TCP_FIN_WAIT1);
414 tcp_fastopen_synack_timer(sk);
415
416
417
418 return;
419 }
420 if (!tp->packets_out)
421 goto out;
422
423 WARN_ON(tcp_rtx_queue_empty(sk));
424
425 tp->tlp_high_seq = 0;
426
427 if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) &&
428 !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) {
429
430
431
432
433
434 struct inet_sock *inet = inet_sk(sk);
435 if (sk->sk_family == AF_INET) {
436 net_dbg_ratelimited("Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
437 &inet->inet_daddr,
438 ntohs(inet->inet_dport),
439 inet->inet_num,
440 tp->snd_una, tp->snd_nxt);
441 }
442#if IS_ENABLED(CONFIG_IPV6)
443 else if (sk->sk_family == AF_INET6) {
444 net_dbg_ratelimited("Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
445 &sk->sk_v6_daddr,
446 ntohs(inet->inet_dport),
447 inet->inet_num,
448 tp->snd_una, tp->snd_nxt);
449 }
450#endif
451 if (tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX) {
452 tcp_write_err(sk);
453 goto out;
454 }
455 tcp_enter_loss(sk);
456 tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1);
457 __sk_dst_reset(sk);
458 goto out_reset_timer;
459 }
460
461 if (tcp_write_timeout(sk))
462 goto out;
463
464 if (icsk->icsk_retransmits == 0) {
465 int mib_idx;
466
467 if (icsk->icsk_ca_state == TCP_CA_Recovery) {
468 if (tcp_is_sack(tp))
469 mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL;
470 else
471 mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL;
472 } else if (icsk->icsk_ca_state == TCP_CA_Loss) {
473 mib_idx = LINUX_MIB_TCPLOSSFAILURES;
474 } else if ((icsk->icsk_ca_state == TCP_CA_Disorder) ||
475 tp->sacked_out) {
476 if (tcp_is_sack(tp))
477 mib_idx = LINUX_MIB_TCPSACKFAILURES;
478 else
479 mib_idx = LINUX_MIB_TCPRENOFAILURES;
480 } else {
481 mib_idx = LINUX_MIB_TCPTIMEOUTS;
482 }
483 __NET_INC_STATS(sock_net(sk), mib_idx);
484 }
485
486 tcp_enter_loss(sk);
487
488 if (tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1) > 0) {
489
490
491
492 if (!icsk->icsk_retransmits)
493 icsk->icsk_retransmits = 1;
494 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
495 min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL),
496 TCP_RTO_MAX);
497 goto out;
498 }
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515 icsk->icsk_backoff++;
516 icsk->icsk_retransmits++;
517
518out_reset_timer:
519
520
521
522
523
524
525
526
527
528 if (sk->sk_state == TCP_ESTABLISHED &&
529 (tp->thin_lto || net->ipv4.sysctl_tcp_thin_linear_timeouts) &&
530 tcp_stream_is_thin(tp) &&
531 icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
532 icsk->icsk_backoff = 0;
533 icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX);
534 } else {
535
536 icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
537 }
538 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
539 if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0))
540 __sk_dst_reset(sk);
541
542out:;
543}
544
545
546
547void tcp_write_timer_handler(struct sock *sk)
548{
549 struct inet_connection_sock *icsk = inet_csk(sk);
550 int event;
551
552 if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
553 !icsk->icsk_pending)
554 goto out;
555
556 if (time_after(icsk->icsk_timeout, jiffies)) {
557 sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout);
558 goto out;
559 }
560
561 tcp_mstamp_refresh(tcp_sk(sk));
562 event = icsk->icsk_pending;
563
564 switch (event) {
565 case ICSK_TIME_REO_TIMEOUT:
566 tcp_rack_reo_timeout(sk);
567 break;
568 case ICSK_TIME_LOSS_PROBE:
569 tcp_send_loss_probe(sk);
570 break;
571 case ICSK_TIME_RETRANS:
572 icsk->icsk_pending = 0;
573 tcp_retransmit_timer(sk);
574 break;
575 case ICSK_TIME_PROBE0:
576 icsk->icsk_pending = 0;
577 tcp_probe_timer(sk);
578 break;
579 }
580
581out:
582 sk_mem_reclaim(sk);
583}
584
585static void tcp_write_timer(struct timer_list *t)
586{
587 struct inet_connection_sock *icsk =
588 from_timer(icsk, t, icsk_retransmit_timer);
589 struct sock *sk = &icsk->icsk_inet.sk;
590
591 bh_lock_sock(sk);
592 if (!sock_owned_by_user(sk)) {
593 tcp_write_timer_handler(sk);
594 } else {
595
596 if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &sk->sk_tsq_flags))
597 sock_hold(sk);
598 }
599 bh_unlock_sock(sk);
600 sock_put(sk);
601}
602
603void tcp_syn_ack_timeout(const struct request_sock *req)
604{
605 struct net *net = read_pnet(&inet_rsk(req)->ireq_net);
606
607 __NET_INC_STATS(net, LINUX_MIB_TCPTIMEOUTS);
608}
609EXPORT_SYMBOL(tcp_syn_ack_timeout);
610
611void tcp_set_keepalive(struct sock *sk, int val)
612{
613 if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))
614 return;
615
616 if (val && !sock_flag(sk, SOCK_KEEPOPEN))
617 inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk)));
618 else if (!val)
619 inet_csk_delete_keepalive_timer(sk);
620}
621EXPORT_SYMBOL_GPL(tcp_set_keepalive);
622
623
624static void tcp_keepalive_timer (struct timer_list *t)
625{
626 struct sock *sk = from_timer(sk, t, sk_timer);
627 struct inet_connection_sock *icsk = inet_csk(sk);
628 struct tcp_sock *tp = tcp_sk(sk);
629 u32 elapsed;
630
631
632 bh_lock_sock(sk);
633 if (sock_owned_by_user(sk)) {
634
635 inet_csk_reset_keepalive_timer (sk, HZ/20);
636 goto out;
637 }
638
639 if (sk->sk_state == TCP_LISTEN) {
640 pr_err("Hmm... keepalive on a LISTEN ???\n");
641 goto out;
642 }
643
644 tcp_mstamp_refresh(tp);
645 if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
646 if (tp->linger2 >= 0) {
647 const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN;
648
649 if (tmo > 0) {
650 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
651 goto out;
652 }
653 }
654 tcp_send_active_reset(sk, GFP_ATOMIC);
655 goto death;
656 }
657
658 if (!sock_flag(sk, SOCK_KEEPOPEN) ||
659 ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)))
660 goto out;
661
662 elapsed = keepalive_time_when(tp);
663
664
665 if (tp->packets_out || !tcp_write_queue_empty(sk))
666 goto resched;
667
668 elapsed = keepalive_time_elapsed(tp);
669
670 if (elapsed >= keepalive_time_when(tp)) {
671
672
673
674 if ((icsk->icsk_user_timeout != 0 &&
675 elapsed >= icsk->icsk_user_timeout &&
676 icsk->icsk_probes_out > 0) ||
677 (icsk->icsk_user_timeout == 0 &&
678 icsk->icsk_probes_out >= keepalive_probes(tp))) {
679 tcp_send_active_reset(sk, GFP_ATOMIC);
680 tcp_write_err(sk);
681 goto out;
682 }
683 if (tcp_write_wakeup(sk, LINUX_MIB_TCPKEEPALIVE) <= 0) {
684 icsk->icsk_probes_out++;
685 elapsed = keepalive_intvl_when(tp);
686 } else {
687
688
689
690 elapsed = TCP_RESOURCE_PROBE_INTERVAL;
691 }
692 } else {
693
694 elapsed = keepalive_time_when(tp) - elapsed;
695 }
696
697 sk_mem_reclaim(sk);
698
699resched:
700 inet_csk_reset_keepalive_timer (sk, elapsed);
701 goto out;
702
703death:
704 tcp_done(sk);
705
706out:
707 bh_unlock_sock(sk);
708 sock_put(sk);
709}
710
711static enum hrtimer_restart tcp_compressed_ack_kick(struct hrtimer *timer)
712{
713 struct tcp_sock *tp = container_of(timer, struct tcp_sock, compressed_ack_timer);
714 struct sock *sk = (struct sock *)tp;
715
716 bh_lock_sock(sk);
717 if (!sock_owned_by_user(sk)) {
718 if (tp->compressed_ack)
719 tcp_send_ack(sk);
720 } else {
721 if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED,
722 &sk->sk_tsq_flags))
723 sock_hold(sk);
724 }
725 bh_unlock_sock(sk);
726
727 sock_put(sk);
728
729 return HRTIMER_NORESTART;
730}
731
732void tcp_init_xmit_timers(struct sock *sk)
733{
734 inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer,
735 &tcp_keepalive_timer);
736 hrtimer_init(&tcp_sk(sk)->pacing_timer, CLOCK_MONOTONIC,
737 HRTIMER_MODE_ABS_PINNED_SOFT);
738 tcp_sk(sk)->pacing_timer.function = tcp_pace_kick;
739
740 hrtimer_init(&tcp_sk(sk)->compressed_ack_timer, CLOCK_MONOTONIC,
741 HRTIMER_MODE_REL_PINNED_SOFT);
742 tcp_sk(sk)->compressed_ack_timer.function = tcp_compressed_ack_kick;
743}
744