Commit | Line | Data |
---|---|---|
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 | ||
36e31b0a | 25 | int sysctl_tcp_thin_linear_timeouts __read_mostly; |
1da177e4 | 26 | |
1da177e4 LT |
27 | static void tcp_write_err(struct sock *sk) |
28 | { | |
29 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
30 | sk->sk_error_report(sk); | |
31 | ||
32 | tcp_done(sk); | |
02a1d6e7 | 33 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT); |
1da177e4 LT |
34 | } |
35 | ||
36 | /* Do not allow orphaned sockets to eat all our resources. | |
37 | * This is direct violation of TCP specs, but it is required | |
38 | * to prevent DoS attacks. It is called when a retransmission timeout | |
39 | * or zero probe timeout occurs on orphaned socket. | |
40 | * | |
caa20d9a | 41 | * Criteria is still not confirmed experimentally and may change. |
1da177e4 LT |
42 | * We kill the socket, if: |
43 | * 1. If number of orphaned sockets exceeds an administratively configured | |
44 | * limit. | |
45 | * 2. If we have strong memory pressure. | |
46 | */ | |
b248230c | 47 | static int tcp_out_of_resources(struct sock *sk, bool do_reset) |
1da177e4 LT |
48 | { |
49 | struct tcp_sock *tp = tcp_sk(sk); | |
ad1af0fe | 50 | int shift = 0; |
1da177e4 | 51 | |
e905a9ed | 52 | /* If peer does not open window for long time, or did not transmit |
1da177e4 LT |
53 | * anything for long time, penalize it. */ |
54 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) | |
ad1af0fe | 55 | shift++; |
1da177e4 LT |
56 | |
57 | /* If some dubious ICMP arrived, penalize even more. */ | |
58 | if (sk->sk_err_soft) | |
ad1af0fe | 59 | shift++; |
1da177e4 | 60 | |
efcdbf24 | 61 | if (tcp_check_oom(sk, shift)) { |
1da177e4 LT |
62 | /* Catch exceptional cases, when connection requires reset. |
63 | * 1. Last segment was sent recently. */ | |
64 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || | |
65 | /* 2. Window is closed. */ | |
66 | (!tp->snd_wnd && !tp->packets_out)) | |
b248230c | 67 | do_reset = true; |
1da177e4 LT |
68 | if (do_reset) |
69 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
70 | tcp_done(sk); | |
02a1d6e7 | 71 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); |
1da177e4 LT |
72 | return 1; |
73 | } | |
74 | return 0; | |
75 | } | |
76 | ||
77 | /* Calculate maximal number or retries on an orphaned socket. */ | |
7533ce30 | 78 | static int tcp_orphan_retries(struct sock *sk, bool alive) |
1da177e4 | 79 | { |
c402d9be | 80 | int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */ |
1da177e4 LT |
81 | |
82 | /* We know from an ICMP that something is wrong. */ | |
83 | if (sk->sk_err_soft && !alive) | |
84 | retries = 0; | |
85 | ||
86 | /* However, if socket sent something recently, select some safe | |
87 | * number of retries. 8 corresponds to >100 seconds with minimal | |
88 | * RTO of 200msec. */ | |
89 | if (retries == 0 && alive) | |
90 | retries = 8; | |
91 | return retries; | |
92 | } | |
93 | ||
ce55dd36 ED |
94 | static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) |
95 | { | |
b0f9ca53 FD |
96 | struct net *net = sock_net(sk); |
97 | ||
ce55dd36 | 98 | /* Black hole detection */ |
b0f9ca53 | 99 | if (net->ipv4.sysctl_tcp_mtu_probing) { |
ce55dd36 ED |
100 | if (!icsk->icsk_mtup.enabled) { |
101 | icsk->icsk_mtup.enabled = 1; | |
05cbc0db | 102 | icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; |
ce55dd36 ED |
103 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); |
104 | } else { | |
b0f9ca53 | 105 | struct net *net = sock_net(sk); |
ce55dd36 | 106 | struct tcp_sock *tp = tcp_sk(sk); |
829942c1 DM |
107 | int mss; |
108 | ||
8beb5c5f | 109 | mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; |
b0f9ca53 | 110 | mss = min(net->ipv4.sysctl_tcp_base_mss, mss); |
ce55dd36 ED |
111 | mss = max(mss, 68 - tp->tcp_header_len); |
112 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
113 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
114 | } | |
115 | } | |
116 | } | |
117 | ||
2f7de571 | 118 | /* This function calculates a "timeout" which is equivalent to the timeout of a |
3ad2f3fb | 119 | * TCP connection after "boundary" unsuccessful, exponentially backed-off |
4d22f7d3 DL |
120 | * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if |
121 | * syn_set flag is set. | |
2f7de571 DL |
122 | */ |
123 | static bool retransmits_timed_out(struct sock *sk, | |
dca43c75 | 124 | unsigned int boundary, |
21a180cd | 125 | unsigned int timeout, |
4d22f7d3 | 126 | bool syn_set) |
2f7de571 | 127 | { |
dca43c75 | 128 | unsigned int linear_backoff_thresh, start_ts; |
4d22f7d3 | 129 | unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN; |
2f7de571 DL |
130 | |
131 | if (!inet_csk(sk)->icsk_retransmits) | |
132 | return false; | |
133 | ||
7faee5c0 ED |
134 | start_ts = tcp_sk(sk)->retrans_stamp; |
135 | if (unlikely(!start_ts)) | |
136 | start_ts = tcp_skb_timestamp(tcp_write_queue_head(sk)); | |
2f7de571 | 137 | |
dca43c75 | 138 | if (likely(timeout == 0)) { |
21a180cd | 139 | linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base); |
2f7de571 | 140 | |
dca43c75 | 141 | if (boundary <= linear_backoff_thresh) |
21a180cd | 142 | timeout = ((2 << boundary) - 1) * rto_base; |
dca43c75 | 143 | else |
21a180cd | 144 | timeout = ((2 << linear_backoff_thresh) - 1) * rto_base + |
dca43c75 JC |
145 | (boundary - linear_backoff_thresh) * TCP_RTO_MAX; |
146 | } | |
2f7de571 DL |
147 | return (tcp_time_stamp - start_ts) >= timeout; |
148 | } | |
149 | ||
1da177e4 LT |
150 | /* A write timeout has occurred. Process the after effects. */ |
151 | static int tcp_write_timeout(struct sock *sk) | |
152 | { | |
5d424d5a | 153 | struct inet_connection_sock *icsk = inet_csk(sk); |
c968601d | 154 | struct tcp_sock *tp = tcp_sk(sk); |
6fa25166 | 155 | struct net *net = sock_net(sk); |
1da177e4 | 156 | int retry_until; |
3db1cd5c | 157 | bool do_reset, syn_set = false; |
1da177e4 LT |
158 | |
159 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
c968601d | 160 | if (icsk->icsk_retransmits) { |
b6c6712a | 161 | dst_negative_advice(sk); |
c968601d | 162 | if (tp->syn_fastopen || tp->syn_data) |
2646c831 | 163 | tcp_fastopen_cache_set(sk, 0, NULL, true, 0); |
dd52bc2b | 164 | if (tp->syn_data && icsk->icsk_retransmits == 1) |
c10d9310 ED |
165 | NET_INC_STATS(sock_net(sk), |
166 | LINUX_MIB_TCPFASTOPENACTIVEFAIL); | |
c968601d | 167 | } |
6fa25166 | 168 | retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries; |
3db1cd5c | 169 | syn_set = true; |
1da177e4 | 170 | } else { |
ae5c3f40 | 171 | if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0, 0)) { |
0e45f4da YC |
172 | /* Some middle-boxes may black-hole Fast Open _after_ |
173 | * the handshake. Therefore we conservatively disable | |
174 | * Fast Open on this path on recurring timeouts with | |
175 | * few or zero bytes acked after Fast Open. | |
176 | */ | |
177 | if (tp->syn_data_acked && | |
178 | tp->bytes_acked <= tp->rx_opt.mss_clamp) { | |
179 | tcp_fastopen_cache_set(sk, 0, NULL, true, 0); | |
ae5c3f40 | 180 | if (icsk->icsk_retransmits == net->ipv4.sysctl_tcp_retries1) |
c10d9310 ED |
181 | NET_INC_STATS(sock_net(sk), |
182 | LINUX_MIB_TCPFASTOPENACTIVEFAIL); | |
0e45f4da | 183 | } |
5d424d5a | 184 | /* Black hole detection */ |
ce55dd36 | 185 | tcp_mtu_probing(icsk, sk); |
1da177e4 | 186 | |
b6c6712a | 187 | dst_negative_advice(sk); |
1da177e4 LT |
188 | } |
189 | ||
c6214a97 | 190 | retry_until = net->ipv4.sysctl_tcp_retries2; |
1da177e4 | 191 | if (sock_flag(sk, SOCK_DEAD)) { |
7533ce30 | 192 | const bool alive = icsk->icsk_rto < TCP_RTO_MAX; |
e905a9ed | 193 | |
1da177e4 | 194 | retry_until = tcp_orphan_retries(sk, alive); |
6fa12c85 | 195 | do_reset = alive || |
21a180cd | 196 | !retransmits_timed_out(sk, retry_until, 0, 0); |
1da177e4 | 197 | |
6fa12c85 | 198 | if (tcp_out_of_resources(sk, do_reset)) |
1da177e4 LT |
199 | return 1; |
200 | } | |
201 | } | |
202 | ||
dca43c75 | 203 | if (retransmits_timed_out(sk, retry_until, |
21a180cd | 204 | syn_set ? 0 : icsk->icsk_user_timeout, syn_set)) { |
1da177e4 LT |
205 | /* Has it gone just too far? */ |
206 | tcp_write_err(sk); | |
207 | return 1; | |
208 | } | |
209 | return 0; | |
210 | } | |
211 | ||
c10d9310 | 212 | /* Called with BH disabled */ |
6f458dfb | 213 | void tcp_delack_timer_handler(struct sock *sk) |
1da177e4 | 214 | { |
1da177e4 | 215 | struct tcp_sock *tp = tcp_sk(sk); |
463c84b9 | 216 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 217 | |
9993e7d3 | 218 | sk_mem_reclaim_partial(sk); |
1da177e4 | 219 | |
463c84b9 | 220 | if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) |
1da177e4 LT |
221 | goto out; |
222 | ||
463c84b9 ACM |
223 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
224 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
225 | goto out; |
226 | } | |
463c84b9 | 227 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 228 | |
b03efcfb | 229 | if (!skb_queue_empty(&tp->ucopy.prequeue)) { |
1da177e4 LT |
230 | struct sk_buff *skb; |
231 | ||
02a1d6e7 | 232 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSCHEDULERFAILED); |
1da177e4 LT |
233 | |
234 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) | |
c57943a1 | 235 | sk_backlog_rcv(sk, skb); |
1da177e4 LT |
236 | |
237 | tp->ucopy.memory = 0; | |
238 | } | |
239 | ||
463c84b9 ACM |
240 | if (inet_csk_ack_scheduled(sk)) { |
241 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 242 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 243 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
244 | } else { |
245 | /* Delayed ACK missed: leave pingpong mode and | |
246 | * deflate ATO. | |
247 | */ | |
463c84b9 ACM |
248 | icsk->icsk_ack.pingpong = 0; |
249 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
250 | } |
251 | tcp_send_ack(sk); | |
02a1d6e7 | 252 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS); |
1da177e4 | 253 | } |
1da177e4 LT |
254 | |
255 | out: | |
b8da51eb | 256 | if (tcp_under_memory_pressure(sk)) |
3ab224be | 257 | sk_mem_reclaim(sk); |
6f458dfb ED |
258 | } |
259 | ||
260 | static void tcp_delack_timer(unsigned long data) | |
261 | { | |
262 | struct sock *sk = (struct sock *)data; | |
263 | ||
264 | bh_lock_sock(sk); | |
265 | if (!sock_owned_by_user(sk)) { | |
266 | tcp_delack_timer_handler(sk); | |
267 | } else { | |
268 | inet_csk(sk)->icsk_ack.blocked = 1; | |
02a1d6e7 | 269 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED); |
6f458dfb | 270 | /* deleguate our work to tcp_release_cb() */ |
144d56e9 ED |
271 | if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags)) |
272 | sock_hold(sk); | |
6f458dfb | 273 | } |
1da177e4 LT |
274 | bh_unlock_sock(sk); |
275 | sock_put(sk); | |
276 | } | |
277 | ||
278 | static void tcp_probe_timer(struct sock *sk) | |
279 | { | |
6687e988 | 280 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
281 | struct tcp_sock *tp = tcp_sk(sk); |
282 | int max_probes; | |
b248230c | 283 | u32 start_ts; |
1da177e4 | 284 | |
fe067e8a | 285 | if (tp->packets_out || !tcp_send_head(sk)) { |
6687e988 | 286 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
287 | return; |
288 | } | |
289 | ||
b248230c YC |
290 | /* RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as |
291 | * long as the receiver continues to respond probes. We support this by | |
292 | * default and reset icsk_probes_out with incoming ACKs. But if the | |
293 | * socket is orphaned or the user specifies TCP_USER_TIMEOUT, we | |
294 | * kill the socket when the retry count and the time exceeds the | |
295 | * corresponding system limit. We also implement similar policy when | |
296 | * we use RTO to probe window in tcp_retransmit_timer(). | |
1da177e4 | 297 | */ |
b248230c YC |
298 | start_ts = tcp_skb_timestamp(tcp_send_head(sk)); |
299 | if (!start_ts) | |
300 | skb_mstamp_get(&tcp_send_head(sk)->skb_mstamp); | |
301 | else if (icsk->icsk_user_timeout && | |
302 | (s32)(tcp_time_stamp - start_ts) > icsk->icsk_user_timeout) | |
303 | goto abort; | |
1da177e4 | 304 | |
c6214a97 | 305 | max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2; |
1da177e4 | 306 | if (sock_flag(sk, SOCK_DEAD)) { |
7533ce30 | 307 | const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX; |
e905a9ed | 308 | |
1da177e4 | 309 | max_probes = tcp_orphan_retries(sk, alive); |
b248230c YC |
310 | if (!alive && icsk->icsk_backoff >= max_probes) |
311 | goto abort; | |
312 | if (tcp_out_of_resources(sk, true)) | |
1da177e4 LT |
313 | return; |
314 | } | |
315 | ||
6687e988 | 316 | if (icsk->icsk_probes_out > max_probes) { |
b248230c | 317 | abort: tcp_write_err(sk); |
1da177e4 LT |
318 | } else { |
319 | /* Only send another probe if we didn't close things up. */ | |
320 | tcp_send_probe0(sk); | |
321 | } | |
322 | } | |
323 | ||
8336886f JC |
324 | /* |
325 | * Timer for Fast Open socket to retransmit SYNACK. Note that the | |
326 | * sk here is the child socket, not the parent (listener) socket. | |
327 | */ | |
328 | static void tcp_fastopen_synack_timer(struct sock *sk) | |
329 | { | |
330 | struct inet_connection_sock *icsk = inet_csk(sk); | |
331 | int max_retries = icsk->icsk_syn_retries ? : | |
7c083ecb | 332 | sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */ |
8336886f JC |
333 | struct request_sock *req; |
334 | ||
335 | req = tcp_sk(sk)->fastopen_rsk; | |
42cb80a2 | 336 | req->rsk_ops->syn_ack_timeout(req); |
8336886f | 337 | |
e6c022a4 | 338 | if (req->num_timeout >= max_retries) { |
8336886f JC |
339 | tcp_write_err(sk); |
340 | return; | |
341 | } | |
342 | /* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error | |
343 | * returned from rtx_syn_ack() to make it more persistent like | |
344 | * regular retransmit because if the child socket has been accepted | |
345 | * it's not good to give up too easily. | |
346 | */ | |
e6c022a4 ED |
347 | inet_rtx_syn_ack(sk, req); |
348 | req->num_timeout++; | |
8336886f | 349 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
e6c022a4 | 350 | TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); |
8336886f JC |
351 | } |
352 | ||
1da177e4 LT |
353 | /* |
354 | * The TCP retransmit timer. | |
355 | */ | |
356 | ||
f1ecd5d9 | 357 | void tcp_retransmit_timer(struct sock *sk) |
1da177e4 LT |
358 | { |
359 | struct tcp_sock *tp = tcp_sk(sk); | |
ae5c3f40 | 360 | struct net *net = sock_net(sk); |
463c84b9 | 361 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 362 | |
8336886f | 363 | if (tp->fastopen_rsk) { |
37561f68 JC |
364 | WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV && |
365 | sk->sk_state != TCP_FIN_WAIT1); | |
8336886f JC |
366 | tcp_fastopen_synack_timer(sk); |
367 | /* Before we receive ACK to our SYN-ACK don't retransmit | |
368 | * anything else (e.g., data or FIN segments). | |
369 | */ | |
370 | return; | |
371 | } | |
1da177e4 LT |
372 | if (!tp->packets_out) |
373 | goto out; | |
374 | ||
547b792c | 375 | WARN_ON(tcp_write_queue_empty(sk)); |
1da177e4 | 376 | |
9b717a8d ND |
377 | tp->tlp_high_seq = 0; |
378 | ||
1da177e4 LT |
379 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && |
380 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
381 | /* Receiver dastardly shrinks window. Our retransmits | |
382 | * become zero probes, but we should not timeout this | |
383 | * connection. If the socket is an orphan, time it out, | |
384 | * we cannot allow such beasts to hang infinitely. | |
385 | */ | |
569508c9 YH |
386 | struct inet_sock *inet = inet_sk(sk); |
387 | if (sk->sk_family == AF_INET) { | |
ba7a46f1 JP |
388 | net_dbg_ratelimited("Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
389 | &inet->inet_daddr, | |
390 | ntohs(inet->inet_dport), | |
391 | inet->inet_num, | |
392 | tp->snd_una, tp->snd_nxt); | |
1da177e4 | 393 | } |
dfd56b8b | 394 | #if IS_ENABLED(CONFIG_IPV6) |
569508c9 | 395 | else if (sk->sk_family == AF_INET6) { |
ba7a46f1 JP |
396 | net_dbg_ratelimited("Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
397 | &sk->sk_v6_daddr, | |
398 | ntohs(inet->inet_dport), | |
399 | inet->inet_num, | |
400 | tp->snd_una, tp->snd_nxt); | |
569508c9 | 401 | } |
1da177e4 LT |
402 | #endif |
403 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { | |
404 | tcp_write_err(sk); | |
405 | goto out; | |
406 | } | |
5ae344c9 | 407 | tcp_enter_loss(sk); |
10d3be56 | 408 | tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1); |
1da177e4 LT |
409 | __sk_dst_reset(sk); |
410 | goto out_reset_timer; | |
411 | } | |
412 | ||
413 | if (tcp_write_timeout(sk)) | |
414 | goto out; | |
415 | ||
463c84b9 | 416 | if (icsk->icsk_retransmits == 0) { |
40b215e5 PE |
417 | int mib_idx; |
418 | ||
c60ce4e2 | 419 | if (icsk->icsk_ca_state == TCP_CA_Recovery) { |
bc079e9e IJ |
420 | if (tcp_is_sack(tp)) |
421 | mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL; | |
422 | else | |
423 | mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL; | |
6687e988 | 424 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
40b215e5 | 425 | mib_idx = LINUX_MIB_TCPLOSSFAILURES; |
c60ce4e2 IJ |
426 | } else if ((icsk->icsk_ca_state == TCP_CA_Disorder) || |
427 | tp->sacked_out) { | |
428 | if (tcp_is_sack(tp)) | |
429 | mib_idx = LINUX_MIB_TCPSACKFAILURES; | |
430 | else | |
431 | mib_idx = LINUX_MIB_TCPRENOFAILURES; | |
1da177e4 | 432 | } else { |
40b215e5 | 433 | mib_idx = LINUX_MIB_TCPTIMEOUTS; |
1da177e4 | 434 | } |
02a1d6e7 | 435 | __NET_INC_STATS(sock_net(sk), mib_idx); |
1da177e4 LT |
436 | } |
437 | ||
5ae344c9 | 438 | tcp_enter_loss(sk); |
1da177e4 | 439 | |
10d3be56 | 440 | if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1) > 0) { |
1da177e4 LT |
441 | /* Retransmission failed because of local congestion, |
442 | * do not backoff. | |
443 | */ | |
463c84b9 ACM |
444 | if (!icsk->icsk_retransmits) |
445 | icsk->icsk_retransmits = 1; | |
446 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
447 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
448 | TCP_RTO_MAX); | |
1da177e4 LT |
449 | goto out; |
450 | } | |
451 | ||
452 | /* Increase the timeout each time we retransmit. Note that | |
453 | * we do not increase the rtt estimate. rto is initialized | |
454 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
455 | * that doubling rto each time is the least we can get away with. | |
456 | * In KA9Q, Karn uses this for the first few times, and then | |
457 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
458 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
459 | * defined in the protocol as the maximum possible RTT. I guess | |
460 | * we'll have to use something other than TCP to talk to the | |
461 | * University of Mars. | |
462 | * | |
463 | * PAWS allows us longer timeouts and large windows, so once | |
464 | * implemented ftp to mars will work nicely. We will have to fix | |
465 | * the 120 second clamps though! | |
466 | */ | |
463c84b9 ACM |
467 | icsk->icsk_backoff++; |
468 | icsk->icsk_retransmits++; | |
1da177e4 LT |
469 | |
470 | out_reset_timer: | |
36e31b0a AP |
471 | /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is |
472 | * used to reset timer, set to 0. Recalculate 'icsk_rto' as this | |
473 | * might be increased if the stream oscillates between thin and thick, | |
474 | * thus the old value might already be too high compared to the value | |
475 | * set by 'tcp_set_rto' in tcp_input.c which resets the rto without | |
476 | * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating | |
477 | * exponential backoff behaviour to avoid continue hammering | |
478 | * linear-timeout retransmissions into a black hole | |
479 | */ | |
480 | if (sk->sk_state == TCP_ESTABLISHED && | |
481 | (tp->thin_lto || sysctl_tcp_thin_linear_timeouts) && | |
482 | tcp_stream_is_thin(tp) && | |
483 | icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) { | |
484 | icsk->icsk_backoff = 0; | |
485 | icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX); | |
486 | } else { | |
487 | /* Use normal (exponential) backoff */ | |
488 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); | |
489 | } | |
3f421baa | 490 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX); |
ae5c3f40 | 491 | if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0, 0)) |
1da177e4 LT |
492 | __sk_dst_reset(sk); |
493 | ||
494 | out:; | |
495 | } | |
496 | ||
c10d9310 | 497 | /* Called with BH disabled */ |
6f458dfb | 498 | void tcp_write_timer_handler(struct sock *sk) |
1da177e4 | 499 | { |
463c84b9 | 500 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
501 | int event; |
502 | ||
463c84b9 | 503 | if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending) |
1da177e4 LT |
504 | goto out; |
505 | ||
463c84b9 ACM |
506 | if (time_after(icsk->icsk_timeout, jiffies)) { |
507 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
508 | goto out; |
509 | } | |
510 | ||
463c84b9 | 511 | event = icsk->icsk_pending; |
1da177e4 LT |
512 | |
513 | switch (event) { | |
6ba8a3b1 ND |
514 | case ICSK_TIME_EARLY_RETRANS: |
515 | tcp_resume_early_retransmit(sk); | |
516 | break; | |
517 | case ICSK_TIME_LOSS_PROBE: | |
518 | tcp_send_loss_probe(sk); | |
519 | break; | |
463c84b9 | 520 | case ICSK_TIME_RETRANS: |
6ba8a3b1 | 521 | icsk->icsk_pending = 0; |
1da177e4 LT |
522 | tcp_retransmit_timer(sk); |
523 | break; | |
463c84b9 | 524 | case ICSK_TIME_PROBE0: |
6ba8a3b1 | 525 | icsk->icsk_pending = 0; |
1da177e4 LT |
526 | tcp_probe_timer(sk); |
527 | break; | |
528 | } | |
1da177e4 LT |
529 | |
530 | out: | |
3ab224be | 531 | sk_mem_reclaim(sk); |
6f458dfb ED |
532 | } |
533 | ||
534 | static void tcp_write_timer(unsigned long data) | |
535 | { | |
536 | struct sock *sk = (struct sock *)data; | |
537 | ||
538 | bh_lock_sock(sk); | |
539 | if (!sock_owned_by_user(sk)) { | |
540 | tcp_write_timer_handler(sk); | |
541 | } else { | |
542 | /* deleguate our work to tcp_release_cb() */ | |
144d56e9 ED |
543 | if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags)) |
544 | sock_hold(sk); | |
6f458dfb | 545 | } |
1da177e4 LT |
546 | bh_unlock_sock(sk); |
547 | sock_put(sk); | |
548 | } | |
549 | ||
42cb80a2 | 550 | void tcp_syn_ack_timeout(const struct request_sock *req) |
72659ecc | 551 | { |
42cb80a2 ED |
552 | struct net *net = read_pnet(&inet_rsk(req)->ireq_net); |
553 | ||
02a1d6e7 | 554 | __NET_INC_STATS(net, LINUX_MIB_TCPTIMEOUTS); |
72659ecc OP |
555 | } |
556 | EXPORT_SYMBOL(tcp_syn_ack_timeout); | |
557 | ||
1da177e4 LT |
558 | void tcp_set_keepalive(struct sock *sk, int val) |
559 | { | |
560 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
561 | return; | |
562 | ||
563 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 564 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 565 | else if (!val) |
463c84b9 | 566 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 LT |
567 | } |
568 | ||
569 | ||
570 | static void tcp_keepalive_timer (unsigned long data) | |
571 | { | |
572 | struct sock *sk = (struct sock *) data; | |
6687e988 | 573 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 574 | struct tcp_sock *tp = tcp_sk(sk); |
6c37e5de | 575 | u32 elapsed; |
1da177e4 LT |
576 | |
577 | /* Only process if socket is not in use. */ | |
578 | bh_lock_sock(sk); | |
579 | if (sock_owned_by_user(sk)) { | |
e905a9ed | 580 | /* Try again later. */ |
463c84b9 | 581 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
582 | goto out; |
583 | } | |
584 | ||
585 | if (sk->sk_state == TCP_LISTEN) { | |
fa76ce73 | 586 | pr_err("Hmm... keepalive on a LISTEN ???\n"); |
1da177e4 LT |
587 | goto out; |
588 | } | |
589 | ||
590 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { | |
591 | if (tp->linger2 >= 0) { | |
463c84b9 | 592 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
593 | |
594 | if (tmo > 0) { | |
595 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
596 | goto out; | |
597 | } | |
598 | } | |
599 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
600 | goto death; | |
601 | } | |
602 | ||
603 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) | |
604 | goto out; | |
605 | ||
606 | elapsed = keepalive_time_when(tp); | |
607 | ||
608 | /* It is alive without keepalive 8) */ | |
fe067e8a | 609 | if (tp->packets_out || tcp_send_head(sk)) |
1da177e4 LT |
610 | goto resched; |
611 | ||
6c37e5de | 612 | elapsed = keepalive_time_elapsed(tp); |
1da177e4 LT |
613 | |
614 | if (elapsed >= keepalive_time_when(tp)) { | |
dca43c75 JC |
615 | /* If the TCP_USER_TIMEOUT option is enabled, use that |
616 | * to determine when to timeout instead. | |
617 | */ | |
618 | if ((icsk->icsk_user_timeout != 0 && | |
619 | elapsed >= icsk->icsk_user_timeout && | |
620 | icsk->icsk_probes_out > 0) || | |
621 | (icsk->icsk_user_timeout == 0 && | |
622 | icsk->icsk_probes_out >= keepalive_probes(tp))) { | |
1da177e4 LT |
623 | tcp_send_active_reset(sk, GFP_ATOMIC); |
624 | tcp_write_err(sk); | |
625 | goto out; | |
626 | } | |
e520af48 | 627 | if (tcp_write_wakeup(sk, LINUX_MIB_TCPKEEPALIVE) <= 0) { |
6687e988 | 628 | icsk->icsk_probes_out++; |
1da177e4 LT |
629 | elapsed = keepalive_intvl_when(tp); |
630 | } else { | |
631 | /* If keepalive was lost due to local congestion, | |
632 | * try harder. | |
633 | */ | |
634 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
635 | } | |
636 | } else { | |
637 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
638 | elapsed = keepalive_time_when(tp) - elapsed; | |
639 | } | |
640 | ||
3ab224be | 641 | sk_mem_reclaim(sk); |
1da177e4 LT |
642 | |
643 | resched: | |
463c84b9 | 644 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
645 | goto out; |
646 | ||
e905a9ed | 647 | death: |
1da177e4 LT |
648 | tcp_done(sk); |
649 | ||
650 | out: | |
651 | bh_unlock_sock(sk); | |
652 | sock_put(sk); | |
653 | } | |
6f458dfb ED |
654 | |
655 | void tcp_init_xmit_timers(struct sock *sk) | |
656 | { | |
657 | inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer, | |
658 | &tcp_keepalive_timer); | |
659 | } |