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Commit | Line | Data |
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1da177e4 LT |
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 | * | |
02c30a84 | 8 | * Authors: Ross Biro |
1da177e4 LT |
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 | ||
21 | #include <linux/module.h> | |
5a0e3ad6 | 22 | #include <linux/gfp.h> |
1da177e4 LT |
23 | #include <net/tcp.h> |
24 | ||
ab32ea5d BH |
25 | int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES; |
26 | int sysctl_tcp_synack_retries __read_mostly = TCP_SYNACK_RETRIES; | |
27 | int sysctl_tcp_keepalive_time __read_mostly = TCP_KEEPALIVE_TIME; | |
28 | int sysctl_tcp_keepalive_probes __read_mostly = TCP_KEEPALIVE_PROBES; | |
29 | int sysctl_tcp_keepalive_intvl __read_mostly = TCP_KEEPALIVE_INTVL; | |
30 | int sysctl_tcp_retries1 __read_mostly = TCP_RETR1; | |
31 | int sysctl_tcp_retries2 __read_mostly = TCP_RETR2; | |
32 | int sysctl_tcp_orphan_retries __read_mostly; | |
36e31b0a | 33 | int sysctl_tcp_thin_linear_timeouts __read_mostly; |
1da177e4 | 34 | |
1da177e4 LT |
35 | static void tcp_write_err(struct sock *sk) |
36 | { | |
37 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
38 | sk->sk_error_report(sk); | |
39 | ||
40 | tcp_done(sk); | |
de0744af | 41 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT); |
1da177e4 LT |
42 | } |
43 | ||
44 | /* Do not allow orphaned sockets to eat all our resources. | |
45 | * This is direct violation of TCP specs, but it is required | |
46 | * to prevent DoS attacks. It is called when a retransmission timeout | |
47 | * or zero probe timeout occurs on orphaned socket. | |
48 | * | |
caa20d9a | 49 | * Criteria is still not confirmed experimentally and may change. |
1da177e4 LT |
50 | * We kill the socket, if: |
51 | * 1. If number of orphaned sockets exceeds an administratively configured | |
52 | * limit. | |
53 | * 2. If we have strong memory pressure. | |
54 | */ | |
55 | static int tcp_out_of_resources(struct sock *sk, int do_reset) | |
56 | { | |
57 | struct tcp_sock *tp = tcp_sk(sk); | |
ad1af0fe | 58 | int shift = 0; |
1da177e4 | 59 | |
e905a9ed | 60 | /* If peer does not open window for long time, or did not transmit |
1da177e4 LT |
61 | * anything for long time, penalize it. */ |
62 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) | |
ad1af0fe | 63 | shift++; |
1da177e4 LT |
64 | |
65 | /* If some dubious ICMP arrived, penalize even more. */ | |
66 | if (sk->sk_err_soft) | |
ad1af0fe | 67 | shift++; |
1da177e4 | 68 | |
efcdbf24 | 69 | if (tcp_check_oom(sk, shift)) { |
1da177e4 LT |
70 | /* Catch exceptional cases, when connection requires reset. |
71 | * 1. Last segment was sent recently. */ | |
72 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || | |
73 | /* 2. Window is closed. */ | |
74 | (!tp->snd_wnd && !tp->packets_out)) | |
75 | do_reset = 1; | |
76 | if (do_reset) | |
77 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
78 | tcp_done(sk); | |
de0744af | 79 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); |
1da177e4 LT |
80 | return 1; |
81 | } | |
82 | return 0; | |
83 | } | |
84 | ||
85 | /* Calculate maximal number or retries on an orphaned socket. */ | |
86 | static int tcp_orphan_retries(struct sock *sk, int alive) | |
87 | { | |
88 | int retries = sysctl_tcp_orphan_retries; /* May be zero. */ | |
89 | ||
90 | /* We know from an ICMP that something is wrong. */ | |
91 | if (sk->sk_err_soft && !alive) | |
92 | retries = 0; | |
93 | ||
94 | /* However, if socket sent something recently, select some safe | |
95 | * number of retries. 8 corresponds to >100 seconds with minimal | |
96 | * RTO of 200msec. */ | |
97 | if (retries == 0 && alive) | |
98 | retries = 8; | |
99 | return retries; | |
100 | } | |
101 | ||
ce55dd36 ED |
102 | static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) |
103 | { | |
ce55dd36 ED |
104 | /* Black hole detection */ |
105 | if (sysctl_tcp_mtu_probing) { | |
106 | if (!icsk->icsk_mtup.enabled) { | |
107 | icsk->icsk_mtup.enabled = 1; | |
108 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
109 | } else { | |
110 | struct tcp_sock *tp = tcp_sk(sk); | |
829942c1 DM |
111 | int mss; |
112 | ||
8beb5c5f | 113 | mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; |
ce55dd36 ED |
114 | mss = min(sysctl_tcp_base_mss, mss); |
115 | mss = max(mss, 68 - tp->tcp_header_len); | |
116 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
117 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
118 | } | |
119 | } | |
120 | } | |
121 | ||
2f7de571 | 122 | /* This function calculates a "timeout" which is equivalent to the timeout of a |
3ad2f3fb | 123 | * TCP connection after "boundary" unsuccessful, exponentially backed-off |
4d22f7d3 DL |
124 | * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if |
125 | * syn_set flag is set. | |
2f7de571 DL |
126 | */ |
127 | static bool retransmits_timed_out(struct sock *sk, | |
dca43c75 | 128 | unsigned int boundary, |
21a180cd | 129 | unsigned int timeout, |
4d22f7d3 | 130 | bool syn_set) |
2f7de571 | 131 | { |
dca43c75 | 132 | unsigned int linear_backoff_thresh, start_ts; |
4d22f7d3 | 133 | unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN; |
2f7de571 DL |
134 | |
135 | if (!inet_csk(sk)->icsk_retransmits) | |
136 | return false; | |
137 | ||
138 | if (unlikely(!tcp_sk(sk)->retrans_stamp)) | |
139 | start_ts = TCP_SKB_CB(tcp_write_queue_head(sk))->when; | |
140 | else | |
141 | start_ts = tcp_sk(sk)->retrans_stamp; | |
142 | ||
dca43c75 | 143 | if (likely(timeout == 0)) { |
21a180cd | 144 | linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base); |
2f7de571 | 145 | |
dca43c75 | 146 | if (boundary <= linear_backoff_thresh) |
21a180cd | 147 | timeout = ((2 << boundary) - 1) * rto_base; |
dca43c75 | 148 | else |
21a180cd | 149 | timeout = ((2 << linear_backoff_thresh) - 1) * rto_base + |
dca43c75 JC |
150 | (boundary - linear_backoff_thresh) * TCP_RTO_MAX; |
151 | } | |
2f7de571 DL |
152 | return (tcp_time_stamp - start_ts) >= timeout; |
153 | } | |
154 | ||
1da177e4 LT |
155 | /* A write timeout has occurred. Process the after effects. */ |
156 | static int tcp_write_timeout(struct sock *sk) | |
157 | { | |
5d424d5a | 158 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 159 | int retry_until; |
3db1cd5c | 160 | bool do_reset, syn_set = false; |
1da177e4 LT |
161 | |
162 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
463c84b9 | 163 | if (icsk->icsk_retransmits) |
b6c6712a | 164 | dst_negative_advice(sk); |
463c84b9 | 165 | retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries; |
3db1cd5c | 166 | syn_set = true; |
1da177e4 | 167 | } else { |
21a180cd | 168 | if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0, 0)) { |
5d424d5a | 169 | /* Black hole detection */ |
ce55dd36 | 170 | tcp_mtu_probing(icsk, sk); |
1da177e4 | 171 | |
b6c6712a | 172 | dst_negative_advice(sk); |
1da177e4 LT |
173 | } |
174 | ||
175 | retry_until = sysctl_tcp_retries2; | |
176 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 177 | const int alive = (icsk->icsk_rto < TCP_RTO_MAX); |
e905a9ed | 178 | |
1da177e4 | 179 | retry_until = tcp_orphan_retries(sk, alive); |
6fa12c85 | 180 | do_reset = alive || |
21a180cd | 181 | !retransmits_timed_out(sk, retry_until, 0, 0); |
1da177e4 | 182 | |
6fa12c85 | 183 | if (tcp_out_of_resources(sk, do_reset)) |
1da177e4 LT |
184 | return 1; |
185 | } | |
186 | } | |
187 | ||
dca43c75 | 188 | if (retransmits_timed_out(sk, retry_until, |
21a180cd | 189 | syn_set ? 0 : icsk->icsk_user_timeout, syn_set)) { |
1da177e4 LT |
190 | /* Has it gone just too far? */ |
191 | tcp_write_err(sk); | |
192 | return 1; | |
193 | } | |
194 | return 0; | |
195 | } | |
196 | ||
6f458dfb | 197 | void tcp_delack_timer_handler(struct sock *sk) |
1da177e4 | 198 | { |
1da177e4 | 199 | struct tcp_sock *tp = tcp_sk(sk); |
463c84b9 | 200 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 201 | |
9993e7d3 | 202 | sk_mem_reclaim_partial(sk); |
1da177e4 | 203 | |
463c84b9 | 204 | if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) |
1da177e4 LT |
205 | goto out; |
206 | ||
463c84b9 ACM |
207 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
208 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
209 | goto out; |
210 | } | |
463c84b9 | 211 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 212 | |
b03efcfb | 213 | if (!skb_queue_empty(&tp->ucopy.prequeue)) { |
1da177e4 LT |
214 | struct sk_buff *skb; |
215 | ||
de0744af | 216 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSCHEDULERFAILED); |
1da177e4 LT |
217 | |
218 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) | |
c57943a1 | 219 | sk_backlog_rcv(sk, skb); |
1da177e4 LT |
220 | |
221 | tp->ucopy.memory = 0; | |
222 | } | |
223 | ||
463c84b9 ACM |
224 | if (inet_csk_ack_scheduled(sk)) { |
225 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 226 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 227 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
228 | } else { |
229 | /* Delayed ACK missed: leave pingpong mode and | |
230 | * deflate ATO. | |
231 | */ | |
463c84b9 ACM |
232 | icsk->icsk_ack.pingpong = 0; |
233 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
234 | } |
235 | tcp_send_ack(sk); | |
de0744af | 236 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS); |
1da177e4 | 237 | } |
1da177e4 LT |
238 | |
239 | out: | |
180d8cd9 | 240 | if (sk_under_memory_pressure(sk)) |
3ab224be | 241 | sk_mem_reclaim(sk); |
6f458dfb ED |
242 | } |
243 | ||
244 | static void tcp_delack_timer(unsigned long data) | |
245 | { | |
246 | struct sock *sk = (struct sock *)data; | |
247 | ||
248 | bh_lock_sock(sk); | |
249 | if (!sock_owned_by_user(sk)) { | |
250 | tcp_delack_timer_handler(sk); | |
251 | } else { | |
252 | inet_csk(sk)->icsk_ack.blocked = 1; | |
253 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED); | |
254 | /* deleguate our work to tcp_release_cb() */ | |
144d56e9 ED |
255 | if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags)) |
256 | sock_hold(sk); | |
6f458dfb | 257 | } |
1da177e4 LT |
258 | bh_unlock_sock(sk); |
259 | sock_put(sk); | |
260 | } | |
261 | ||
262 | static void tcp_probe_timer(struct sock *sk) | |
263 | { | |
6687e988 | 264 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
265 | struct tcp_sock *tp = tcp_sk(sk); |
266 | int max_probes; | |
267 | ||
fe067e8a | 268 | if (tp->packets_out || !tcp_send_head(sk)) { |
6687e988 | 269 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
270 | return; |
271 | } | |
272 | ||
273 | /* *WARNING* RFC 1122 forbids this | |
274 | * | |
275 | * It doesn't AFAIK, because we kill the retransmit timer -AK | |
276 | * | |
277 | * FIXME: We ought not to do it, Solaris 2.5 actually has fixing | |
278 | * this behaviour in Solaris down as a bug fix. [AC] | |
279 | * | |
6687e988 | 280 | * Let me to explain. icsk_probes_out is zeroed by incoming ACKs |
1da177e4 LT |
281 | * even if they advertise zero window. Hence, connection is killed only |
282 | * if we received no ACKs for normal connection timeout. It is not killed | |
283 | * only because window stays zero for some time, window may be zero | |
284 | * until armageddon and even later. We are in full accordance | |
285 | * with RFCs, only probe timer combines both retransmission timeout | |
286 | * and probe timeout in one bottle. --ANK | |
287 | */ | |
288 | max_probes = sysctl_tcp_retries2; | |
289 | ||
290 | if (sock_flag(sk, SOCK_DEAD)) { | |
463c84b9 | 291 | const int alive = ((icsk->icsk_rto << icsk->icsk_backoff) < TCP_RTO_MAX); |
e905a9ed | 292 | |
1da177e4 LT |
293 | max_probes = tcp_orphan_retries(sk, alive); |
294 | ||
6687e988 | 295 | if (tcp_out_of_resources(sk, alive || icsk->icsk_probes_out <= max_probes)) |
1da177e4 LT |
296 | return; |
297 | } | |
298 | ||
6687e988 | 299 | if (icsk->icsk_probes_out > max_probes) { |
1da177e4 LT |
300 | tcp_write_err(sk); |
301 | } else { | |
302 | /* Only send another probe if we didn't close things up. */ | |
303 | tcp_send_probe0(sk); | |
304 | } | |
305 | } | |
306 | ||
8336886f JC |
307 | /* |
308 | * Timer for Fast Open socket to retransmit SYNACK. Note that the | |
309 | * sk here is the child socket, not the parent (listener) socket. | |
310 | */ | |
311 | static void tcp_fastopen_synack_timer(struct sock *sk) | |
312 | { | |
313 | struct inet_connection_sock *icsk = inet_csk(sk); | |
314 | int max_retries = icsk->icsk_syn_retries ? : | |
315 | sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */ | |
316 | struct request_sock *req; | |
317 | ||
318 | req = tcp_sk(sk)->fastopen_rsk; | |
319 | req->rsk_ops->syn_ack_timeout(sk, req); | |
320 | ||
e6c022a4 | 321 | if (req->num_timeout >= max_retries) { |
8336886f JC |
322 | tcp_write_err(sk); |
323 | return; | |
324 | } | |
325 | /* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error | |
326 | * returned from rtx_syn_ack() to make it more persistent like | |
327 | * regular retransmit because if the child socket has been accepted | |
328 | * it's not good to give up too easily. | |
329 | */ | |
e6c022a4 ED |
330 | inet_rtx_syn_ack(sk, req); |
331 | req->num_timeout++; | |
8336886f | 332 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
e6c022a4 | 333 | TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); |
8336886f JC |
334 | } |
335 | ||
1da177e4 LT |
336 | /* |
337 | * The TCP retransmit timer. | |
338 | */ | |
339 | ||
f1ecd5d9 | 340 | void tcp_retransmit_timer(struct sock *sk) |
1da177e4 LT |
341 | { |
342 | struct tcp_sock *tp = tcp_sk(sk); | |
463c84b9 | 343 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 344 | |
8336886f | 345 | if (tp->fastopen_rsk) { |
37561f68 JC |
346 | WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV && |
347 | sk->sk_state != TCP_FIN_WAIT1); | |
8336886f JC |
348 | tcp_fastopen_synack_timer(sk); |
349 | /* Before we receive ACK to our SYN-ACK don't retransmit | |
350 | * anything else (e.g., data or FIN segments). | |
351 | */ | |
352 | return; | |
353 | } | |
1da177e4 LT |
354 | if (!tp->packets_out) |
355 | goto out; | |
356 | ||
547b792c | 357 | WARN_ON(tcp_write_queue_empty(sk)); |
1da177e4 | 358 | |
9b717a8d ND |
359 | tp->tlp_high_seq = 0; |
360 | ||
1da177e4 LT |
361 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && |
362 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
363 | /* Receiver dastardly shrinks window. Our retransmits | |
364 | * become zero probes, but we should not timeout this | |
365 | * connection. If the socket is an orphan, time it out, | |
366 | * we cannot allow such beasts to hang infinitely. | |
367 | */ | |
569508c9 YH |
368 | struct inet_sock *inet = inet_sk(sk); |
369 | if (sk->sk_family == AF_INET) { | |
afd46503 JP |
370 | LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n"), |
371 | &inet->inet_daddr, | |
372 | ntohs(inet->inet_dport), inet->inet_num, | |
373 | tp->snd_una, tp->snd_nxt); | |
1da177e4 | 374 | } |
dfd56b8b | 375 | #if IS_ENABLED(CONFIG_IPV6) |
569508c9 YH |
376 | else if (sk->sk_family == AF_INET6) { |
377 | struct ipv6_pinfo *np = inet6_sk(sk); | |
afd46503 JP |
378 | LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n"), |
379 | &np->daddr, | |
380 | ntohs(inet->inet_dport), inet->inet_num, | |
381 | tp->snd_una, tp->snd_nxt); | |
569508c9 | 382 | } |
1da177e4 LT |
383 | #endif |
384 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { | |
385 | tcp_write_err(sk); | |
386 | goto out; | |
387 | } | |
388 | tcp_enter_loss(sk, 0); | |
fe067e8a | 389 | tcp_retransmit_skb(sk, tcp_write_queue_head(sk)); |
1da177e4 LT |
390 | __sk_dst_reset(sk); |
391 | goto out_reset_timer; | |
392 | } | |
393 | ||
394 | if (tcp_write_timeout(sk)) | |
395 | goto out; | |
396 | ||
463c84b9 | 397 | if (icsk->icsk_retransmits == 0) { |
40b215e5 PE |
398 | int mib_idx; |
399 | ||
c60ce4e2 | 400 | if (icsk->icsk_ca_state == TCP_CA_Recovery) { |
bc079e9e IJ |
401 | if (tcp_is_sack(tp)) |
402 | mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL; | |
403 | else | |
404 | mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL; | |
6687e988 | 405 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
40b215e5 | 406 | mib_idx = LINUX_MIB_TCPLOSSFAILURES; |
c60ce4e2 IJ |
407 | } else if ((icsk->icsk_ca_state == TCP_CA_Disorder) || |
408 | tp->sacked_out) { | |
409 | if (tcp_is_sack(tp)) | |
410 | mib_idx = LINUX_MIB_TCPSACKFAILURES; | |
411 | else | |
412 | mib_idx = LINUX_MIB_TCPRENOFAILURES; | |
1da177e4 | 413 | } else { |
40b215e5 | 414 | mib_idx = LINUX_MIB_TCPTIMEOUTS; |
1da177e4 | 415 | } |
de0744af | 416 | NET_INC_STATS_BH(sock_net(sk), mib_idx); |
1da177e4 LT |
417 | } |
418 | ||
9b44190d | 419 | tcp_enter_loss(sk, 0); |
1da177e4 | 420 | |
fe067e8a | 421 | if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) { |
1da177e4 LT |
422 | /* Retransmission failed because of local congestion, |
423 | * do not backoff. | |
424 | */ | |
463c84b9 ACM |
425 | if (!icsk->icsk_retransmits) |
426 | icsk->icsk_retransmits = 1; | |
427 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
428 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
429 | TCP_RTO_MAX); | |
1da177e4 LT |
430 | goto out; |
431 | } | |
432 | ||
433 | /* Increase the timeout each time we retransmit. Note that | |
434 | * we do not increase the rtt estimate. rto is initialized | |
435 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
436 | * that doubling rto each time is the least we can get away with. | |
437 | * In KA9Q, Karn uses this for the first few times, and then | |
438 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
439 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
440 | * defined in the protocol as the maximum possible RTT. I guess | |
441 | * we'll have to use something other than TCP to talk to the | |
442 | * University of Mars. | |
443 | * | |
444 | * PAWS allows us longer timeouts and large windows, so once | |
445 | * implemented ftp to mars will work nicely. We will have to fix | |
446 | * the 120 second clamps though! | |
447 | */ | |
463c84b9 ACM |
448 | icsk->icsk_backoff++; |
449 | icsk->icsk_retransmits++; | |
1da177e4 LT |
450 | |
451 | out_reset_timer: | |
36e31b0a AP |
452 | /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is |
453 | * used to reset timer, set to 0. Recalculate 'icsk_rto' as this | |
454 | * might be increased if the stream oscillates between thin and thick, | |
455 | * thus the old value might already be too high compared to the value | |
456 | * set by 'tcp_set_rto' in tcp_input.c which resets the rto without | |
457 | * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating | |
458 | * exponential backoff behaviour to avoid continue hammering | |
459 | * linear-timeout retransmissions into a black hole | |
460 | */ | |
461 | if (sk->sk_state == TCP_ESTABLISHED && | |
462 | (tp->thin_lto || sysctl_tcp_thin_linear_timeouts) && | |
463 | tcp_stream_is_thin(tp) && | |
464 | icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) { | |
465 | icsk->icsk_backoff = 0; | |
466 | icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX); | |
467 | } else { | |
468 | /* Use normal (exponential) backoff */ | |
469 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); | |
470 | } | |
3f421baa | 471 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX); |
21a180cd | 472 | if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1, 0, 0)) |
1da177e4 LT |
473 | __sk_dst_reset(sk); |
474 | ||
475 | out:; | |
476 | } | |
477 | ||
6f458dfb | 478 | void tcp_write_timer_handler(struct sock *sk) |
1da177e4 | 479 | { |
463c84b9 | 480 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
481 | int event; |
482 | ||
463c84b9 | 483 | if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending) |
1da177e4 LT |
484 | goto out; |
485 | ||
463c84b9 ACM |
486 | if (time_after(icsk->icsk_timeout, jiffies)) { |
487 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
488 | goto out; |
489 | } | |
490 | ||
463c84b9 | 491 | event = icsk->icsk_pending; |
1da177e4 LT |
492 | |
493 | switch (event) { | |
6ba8a3b1 ND |
494 | case ICSK_TIME_EARLY_RETRANS: |
495 | tcp_resume_early_retransmit(sk); | |
496 | break; | |
497 | case ICSK_TIME_LOSS_PROBE: | |
498 | tcp_send_loss_probe(sk); | |
499 | break; | |
463c84b9 | 500 | case ICSK_TIME_RETRANS: |
6ba8a3b1 | 501 | icsk->icsk_pending = 0; |
1da177e4 LT |
502 | tcp_retransmit_timer(sk); |
503 | break; | |
463c84b9 | 504 | case ICSK_TIME_PROBE0: |
6ba8a3b1 | 505 | icsk->icsk_pending = 0; |
1da177e4 LT |
506 | tcp_probe_timer(sk); |
507 | break; | |
508 | } | |
1da177e4 LT |
509 | |
510 | out: | |
3ab224be | 511 | sk_mem_reclaim(sk); |
6f458dfb ED |
512 | } |
513 | ||
514 | static void tcp_write_timer(unsigned long data) | |
515 | { | |
516 | struct sock *sk = (struct sock *)data; | |
517 | ||
518 | bh_lock_sock(sk); | |
519 | if (!sock_owned_by_user(sk)) { | |
520 | tcp_write_timer_handler(sk); | |
521 | } else { | |
522 | /* deleguate our work to tcp_release_cb() */ | |
144d56e9 ED |
523 | if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags)) |
524 | sock_hold(sk); | |
6f458dfb | 525 | } |
1da177e4 LT |
526 | bh_unlock_sock(sk); |
527 | sock_put(sk); | |
528 | } | |
529 | ||
295f7324 ACM |
530 | /* |
531 | * Timer for listening sockets | |
532 | */ | |
533 | ||
534 | static void tcp_synack_timer(struct sock *sk) | |
535 | { | |
a019d6fe ACM |
536 | inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, |
537 | TCP_TIMEOUT_INIT, TCP_RTO_MAX); | |
1da177e4 LT |
538 | } |
539 | ||
72659ecc OP |
540 | void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req) |
541 | { | |
542 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPTIMEOUTS); | |
543 | } | |
544 | EXPORT_SYMBOL(tcp_syn_ack_timeout); | |
545 | ||
1da177e4 LT |
546 | void tcp_set_keepalive(struct sock *sk, int val) |
547 | { | |
548 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
549 | return; | |
550 | ||
551 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 552 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 553 | else if (!val) |
463c84b9 | 554 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 LT |
555 | } |
556 | ||
557 | ||
558 | static void tcp_keepalive_timer (unsigned long data) | |
559 | { | |
560 | struct sock *sk = (struct sock *) data; | |
6687e988 | 561 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 562 | struct tcp_sock *tp = tcp_sk(sk); |
6c37e5de | 563 | u32 elapsed; |
1da177e4 LT |
564 | |
565 | /* Only process if socket is not in use. */ | |
566 | bh_lock_sock(sk); | |
567 | if (sock_owned_by_user(sk)) { | |
e905a9ed | 568 | /* Try again later. */ |
463c84b9 | 569 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
570 | goto out; |
571 | } | |
572 | ||
573 | if (sk->sk_state == TCP_LISTEN) { | |
574 | tcp_synack_timer(sk); | |
575 | goto out; | |
576 | } | |
577 | ||
578 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { | |
579 | if (tp->linger2 >= 0) { | |
463c84b9 | 580 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
581 | |
582 | if (tmo > 0) { | |
583 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
584 | goto out; | |
585 | } | |
586 | } | |
587 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
588 | goto death; | |
589 | } | |
590 | ||
591 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) | |
592 | goto out; | |
593 | ||
594 | elapsed = keepalive_time_when(tp); | |
595 | ||
596 | /* It is alive without keepalive 8) */ | |
fe067e8a | 597 | if (tp->packets_out || tcp_send_head(sk)) |
1da177e4 LT |
598 | goto resched; |
599 | ||
6c37e5de | 600 | elapsed = keepalive_time_elapsed(tp); |
1da177e4 LT |
601 | |
602 | if (elapsed >= keepalive_time_when(tp)) { | |
dca43c75 JC |
603 | /* If the TCP_USER_TIMEOUT option is enabled, use that |
604 | * to determine when to timeout instead. | |
605 | */ | |
606 | if ((icsk->icsk_user_timeout != 0 && | |
607 | elapsed >= icsk->icsk_user_timeout && | |
608 | icsk->icsk_probes_out > 0) || | |
609 | (icsk->icsk_user_timeout == 0 && | |
610 | icsk->icsk_probes_out >= keepalive_probes(tp))) { | |
1da177e4 LT |
611 | tcp_send_active_reset(sk, GFP_ATOMIC); |
612 | tcp_write_err(sk); | |
613 | goto out; | |
614 | } | |
615 | if (tcp_write_wakeup(sk) <= 0) { | |
6687e988 | 616 | icsk->icsk_probes_out++; |
1da177e4 LT |
617 | elapsed = keepalive_intvl_when(tp); |
618 | } else { | |
619 | /* If keepalive was lost due to local congestion, | |
620 | * try harder. | |
621 | */ | |
622 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
623 | } | |
624 | } else { | |
625 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
626 | elapsed = keepalive_time_when(tp) - elapsed; | |
627 | } | |
628 | ||
3ab224be | 629 | sk_mem_reclaim(sk); |
1da177e4 LT |
630 | |
631 | resched: | |
463c84b9 | 632 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
633 | goto out; |
634 | ||
e905a9ed | 635 | death: |
1da177e4 LT |
636 | tcp_done(sk); |
637 | ||
638 | out: | |
639 | bh_unlock_sock(sk); | |
640 | sock_put(sk); | |
641 | } | |
6f458dfb ED |
642 | |
643 | void tcp_init_xmit_timers(struct sock *sk) | |
644 | { | |
645 | inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer, | |
646 | &tcp_keepalive_timer); | |
647 | } | |
648 | EXPORT_SYMBOL(tcp_init_xmit_timers); |