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 | ||
36e31b0a | 25 | int sysctl_tcp_thin_linear_timeouts __read_mostly; |
1da177e4 | 26 | |
c380d37e RS |
27 | /** |
28 | * tcp_write_err() - close socket and save error info | |
29 | * @sk: The socket the error has appeared on. | |
30 | * | |
31 | * Returns: Nothing (void) | |
32 | */ | |
33 | ||
1da177e4 LT |
34 | static void tcp_write_err(struct sock *sk) |
35 | { | |
36 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
37 | sk->sk_error_report(sk); | |
38 | ||
39 | tcp_done(sk); | |
02a1d6e7 | 40 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT); |
1da177e4 LT |
41 | } |
42 | ||
c380d37e RS |
43 | /** |
44 | * tcp_out_of_resources() - Close socket if out of resources | |
45 | * @sk: pointer to current socket | |
46 | * @do_reset: send a last packet with reset flag | |
1da177e4 | 47 | * |
c380d37e RS |
48 | * Do not allow orphaned sockets to eat all our resources. |
49 | * This is direct violation of TCP specs, but it is required | |
50 | * to prevent DoS attacks. It is called when a retransmission timeout | |
51 | * or zero probe timeout occurs on orphaned socket. | |
52 | * | |
53 | * Criteria is still not confirmed experimentally and may change. | |
54 | * We kill the socket, if: | |
55 | * 1. If number of orphaned sockets exceeds an administratively configured | |
56 | * limit. | |
57 | * 2. If we have strong memory pressure. | |
1da177e4 | 58 | */ |
b248230c | 59 | static int tcp_out_of_resources(struct sock *sk, bool do_reset) |
1da177e4 LT |
60 | { |
61 | struct tcp_sock *tp = tcp_sk(sk); | |
ad1af0fe | 62 | int shift = 0; |
1da177e4 | 63 | |
e905a9ed | 64 | /* If peer does not open window for long time, or did not transmit |
1da177e4 LT |
65 | * anything for long time, penalize it. */ |
66 | if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) | |
ad1af0fe | 67 | shift++; |
1da177e4 LT |
68 | |
69 | /* If some dubious ICMP arrived, penalize even more. */ | |
70 | if (sk->sk_err_soft) | |
ad1af0fe | 71 | shift++; |
1da177e4 | 72 | |
efcdbf24 | 73 | if (tcp_check_oom(sk, shift)) { |
1da177e4 LT |
74 | /* Catch exceptional cases, when connection requires reset. |
75 | * 1. Last segment was sent recently. */ | |
76 | if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN || | |
77 | /* 2. Window is closed. */ | |
78 | (!tp->snd_wnd && !tp->packets_out)) | |
b248230c | 79 | do_reset = true; |
1da177e4 LT |
80 | if (do_reset) |
81 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
82 | tcp_done(sk); | |
02a1d6e7 | 83 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); |
1da177e4 LT |
84 | return 1; |
85 | } | |
86 | return 0; | |
87 | } | |
88 | ||
c380d37e RS |
89 | /** |
90 | * tcp_orphan_retries() - Returns maximal number of retries on an orphaned socket | |
91 | * @sk: Pointer to the current socket. | |
92 | * @alive: bool, socket alive state | |
93 | */ | |
7533ce30 | 94 | static int tcp_orphan_retries(struct sock *sk, bool alive) |
1da177e4 | 95 | { |
c402d9be | 96 | int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */ |
1da177e4 LT |
97 | |
98 | /* We know from an ICMP that something is wrong. */ | |
99 | if (sk->sk_err_soft && !alive) | |
100 | retries = 0; | |
101 | ||
102 | /* However, if socket sent something recently, select some safe | |
103 | * number of retries. 8 corresponds to >100 seconds with minimal | |
104 | * RTO of 200msec. */ | |
105 | if (retries == 0 && alive) | |
106 | retries = 8; | |
107 | return retries; | |
108 | } | |
109 | ||
ce55dd36 ED |
110 | static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) |
111 | { | |
b0f9ca53 FD |
112 | struct net *net = sock_net(sk); |
113 | ||
ce55dd36 | 114 | /* Black hole detection */ |
b0f9ca53 | 115 | if (net->ipv4.sysctl_tcp_mtu_probing) { |
ce55dd36 ED |
116 | if (!icsk->icsk_mtup.enabled) { |
117 | icsk->icsk_mtup.enabled = 1; | |
05cbc0db | 118 | icsk->icsk_mtup.probe_timestamp = tcp_time_stamp; |
ce55dd36 ED |
119 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); |
120 | } else { | |
b0f9ca53 | 121 | struct net *net = sock_net(sk); |
ce55dd36 | 122 | struct tcp_sock *tp = tcp_sk(sk); |
829942c1 DM |
123 | int mss; |
124 | ||
8beb5c5f | 125 | mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; |
b0f9ca53 | 126 | mss = min(net->ipv4.sysctl_tcp_base_mss, mss); |
ce55dd36 ED |
127 | mss = max(mss, 68 - tp->tcp_header_len); |
128 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
129 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
130 | } | |
131 | } | |
132 | } | |
133 | ||
c380d37e RS |
134 | |
135 | /** | |
136 | * retransmits_timed_out() - returns true if this connection has timed out | |
137 | * @sk: The current socket | |
138 | * @boundary: max number of retransmissions | |
139 | * @timeout: A custom timeout value. | |
140 | * If set to 0 the default timeout is calculated and used. | |
141 | * Using TCP_RTO_MIN and the number of unsuccessful retransmits. | |
142 | * @syn_set: true if the SYN Bit was set. | |
143 | * | |
144 | * The default "timeout" value this function can calculate and use | |
145 | * is equivalent to the timeout of a TCP Connection | |
146 | * after "boundary" unsuccessful, exponentially backed-off | |
4d22f7d3 DL |
147 | * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if |
148 | * syn_set flag is set. | |
c380d37e | 149 | * |
2f7de571 DL |
150 | */ |
151 | static bool retransmits_timed_out(struct sock *sk, | |
dca43c75 | 152 | unsigned int boundary, |
21a180cd | 153 | unsigned int timeout, |
4d22f7d3 | 154 | bool syn_set) |
2f7de571 | 155 | { |
dca43c75 | 156 | unsigned int linear_backoff_thresh, start_ts; |
4d22f7d3 | 157 | unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN; |
2f7de571 DL |
158 | |
159 | if (!inet_csk(sk)->icsk_retransmits) | |
160 | return false; | |
161 | ||
7faee5c0 ED |
162 | start_ts = tcp_sk(sk)->retrans_stamp; |
163 | if (unlikely(!start_ts)) | |
164 | start_ts = tcp_skb_timestamp(tcp_write_queue_head(sk)); | |
2f7de571 | 165 | |
dca43c75 | 166 | if (likely(timeout == 0)) { |
21a180cd | 167 | linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base); |
2f7de571 | 168 | |
dca43c75 | 169 | if (boundary <= linear_backoff_thresh) |
21a180cd | 170 | timeout = ((2 << boundary) - 1) * rto_base; |
dca43c75 | 171 | else |
21a180cd | 172 | timeout = ((2 << linear_backoff_thresh) - 1) * rto_base + |
dca43c75 JC |
173 | (boundary - linear_backoff_thresh) * TCP_RTO_MAX; |
174 | } | |
2f7de571 DL |
175 | return (tcp_time_stamp - start_ts) >= timeout; |
176 | } | |
177 | ||
1da177e4 LT |
178 | /* A write timeout has occurred. Process the after effects. */ |
179 | static int tcp_write_timeout(struct sock *sk) | |
180 | { | |
5d424d5a | 181 | struct inet_connection_sock *icsk = inet_csk(sk); |
c968601d | 182 | struct tcp_sock *tp = tcp_sk(sk); |
6fa25166 | 183 | struct net *net = sock_net(sk); |
1da177e4 | 184 | int retry_until; |
3db1cd5c | 185 | bool do_reset, syn_set = false; |
1da177e4 LT |
186 | |
187 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
c968601d | 188 | if (icsk->icsk_retransmits) { |
b6c6712a | 189 | dst_negative_advice(sk); |
c968601d | 190 | if (tp->syn_fastopen || tp->syn_data) |
2646c831 | 191 | tcp_fastopen_cache_set(sk, 0, NULL, true, 0); |
dd52bc2b | 192 | if (tp->syn_data && icsk->icsk_retransmits == 1) |
c10d9310 ED |
193 | NET_INC_STATS(sock_net(sk), |
194 | LINUX_MIB_TCPFASTOPENACTIVEFAIL); | |
c968601d | 195 | } |
6fa25166 | 196 | retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries; |
3db1cd5c | 197 | syn_set = true; |
1da177e4 | 198 | } else { |
ae5c3f40 | 199 | if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0, 0)) { |
0e45f4da YC |
200 | /* Some middle-boxes may black-hole Fast Open _after_ |
201 | * the handshake. Therefore we conservatively disable | |
202 | * Fast Open on this path on recurring timeouts with | |
203 | * few or zero bytes acked after Fast Open. | |
204 | */ | |
205 | if (tp->syn_data_acked && | |
206 | tp->bytes_acked <= tp->rx_opt.mss_clamp) { | |
207 | tcp_fastopen_cache_set(sk, 0, NULL, true, 0); | |
ae5c3f40 | 208 | if (icsk->icsk_retransmits == net->ipv4.sysctl_tcp_retries1) |
c10d9310 ED |
209 | NET_INC_STATS(sock_net(sk), |
210 | LINUX_MIB_TCPFASTOPENACTIVEFAIL); | |
0e45f4da | 211 | } |
5d424d5a | 212 | /* Black hole detection */ |
ce55dd36 | 213 | tcp_mtu_probing(icsk, sk); |
1da177e4 | 214 | |
b6c6712a | 215 | dst_negative_advice(sk); |
1da177e4 LT |
216 | } |
217 | ||
c6214a97 | 218 | retry_until = net->ipv4.sysctl_tcp_retries2; |
1da177e4 | 219 | if (sock_flag(sk, SOCK_DEAD)) { |
7533ce30 | 220 | const bool alive = icsk->icsk_rto < TCP_RTO_MAX; |
e905a9ed | 221 | |
1da177e4 | 222 | retry_until = tcp_orphan_retries(sk, alive); |
6fa12c85 | 223 | do_reset = alive || |
21a180cd | 224 | !retransmits_timed_out(sk, retry_until, 0, 0); |
1da177e4 | 225 | |
6fa12c85 | 226 | if (tcp_out_of_resources(sk, do_reset)) |
1da177e4 LT |
227 | return 1; |
228 | } | |
229 | } | |
230 | ||
dca43c75 | 231 | if (retransmits_timed_out(sk, retry_until, |
21a180cd | 232 | syn_set ? 0 : icsk->icsk_user_timeout, syn_set)) { |
1da177e4 LT |
233 | /* Has it gone just too far? */ |
234 | tcp_write_err(sk); | |
235 | return 1; | |
236 | } | |
237 | return 0; | |
238 | } | |
239 | ||
c10d9310 | 240 | /* Called with BH disabled */ |
6f458dfb | 241 | void tcp_delack_timer_handler(struct sock *sk) |
1da177e4 | 242 | { |
1da177e4 | 243 | struct tcp_sock *tp = tcp_sk(sk); |
463c84b9 | 244 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 245 | |
9993e7d3 | 246 | sk_mem_reclaim_partial(sk); |
1da177e4 | 247 | |
463c84b9 | 248 | if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) |
1da177e4 LT |
249 | goto out; |
250 | ||
463c84b9 ACM |
251 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
252 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
253 | goto out; |
254 | } | |
463c84b9 | 255 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 256 | |
b03efcfb | 257 | if (!skb_queue_empty(&tp->ucopy.prequeue)) { |
1da177e4 LT |
258 | struct sk_buff *skb; |
259 | ||
02a1d6e7 | 260 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSCHEDULERFAILED); |
1da177e4 LT |
261 | |
262 | while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) | |
c57943a1 | 263 | sk_backlog_rcv(sk, skb); |
1da177e4 LT |
264 | |
265 | tp->ucopy.memory = 0; | |
266 | } | |
267 | ||
463c84b9 ACM |
268 | if (inet_csk_ack_scheduled(sk)) { |
269 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 270 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 271 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
272 | } else { |
273 | /* Delayed ACK missed: leave pingpong mode and | |
274 | * deflate ATO. | |
275 | */ | |
463c84b9 ACM |
276 | icsk->icsk_ack.pingpong = 0; |
277 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
278 | } |
279 | tcp_send_ack(sk); | |
02a1d6e7 | 280 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS); |
1da177e4 | 281 | } |
1da177e4 LT |
282 | |
283 | out: | |
b8da51eb | 284 | if (tcp_under_memory_pressure(sk)) |
3ab224be | 285 | sk_mem_reclaim(sk); |
6f458dfb ED |
286 | } |
287 | ||
c380d37e RS |
288 | |
289 | /** | |
290 | * tcp_delack_timer() - The TCP delayed ACK timeout handler | |
291 | * @data: Pointer to the current socket. (gets casted to struct sock *) | |
292 | * | |
293 | * This function gets (indirectly) called when the kernel timer for a TCP packet | |
294 | * of this socket expires. Calls tcp_delack_timer_handler() to do the actual work. | |
295 | * | |
296 | * Returns: Nothing (void) | |
297 | */ | |
6f458dfb ED |
298 | static void tcp_delack_timer(unsigned long data) |
299 | { | |
300 | struct sock *sk = (struct sock *)data; | |
301 | ||
302 | bh_lock_sock(sk); | |
303 | if (!sock_owned_by_user(sk)) { | |
304 | tcp_delack_timer_handler(sk); | |
305 | } else { | |
306 | inet_csk(sk)->icsk_ack.blocked = 1; | |
02a1d6e7 | 307 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED); |
6f458dfb | 308 | /* deleguate our work to tcp_release_cb() */ |
144d56e9 ED |
309 | if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags)) |
310 | sock_hold(sk); | |
6f458dfb | 311 | } |
1da177e4 LT |
312 | bh_unlock_sock(sk); |
313 | sock_put(sk); | |
314 | } | |
315 | ||
316 | static void tcp_probe_timer(struct sock *sk) | |
317 | { | |
6687e988 | 318 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
319 | struct tcp_sock *tp = tcp_sk(sk); |
320 | int max_probes; | |
b248230c | 321 | u32 start_ts; |
1da177e4 | 322 | |
fe067e8a | 323 | if (tp->packets_out || !tcp_send_head(sk)) { |
6687e988 | 324 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
325 | return; |
326 | } | |
327 | ||
b248230c YC |
328 | /* RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as |
329 | * long as the receiver continues to respond probes. We support this by | |
330 | * default and reset icsk_probes_out with incoming ACKs. But if the | |
331 | * socket is orphaned or the user specifies TCP_USER_TIMEOUT, we | |
332 | * kill the socket when the retry count and the time exceeds the | |
333 | * corresponding system limit. We also implement similar policy when | |
334 | * we use RTO to probe window in tcp_retransmit_timer(). | |
1da177e4 | 335 | */ |
b248230c YC |
336 | start_ts = tcp_skb_timestamp(tcp_send_head(sk)); |
337 | if (!start_ts) | |
338 | skb_mstamp_get(&tcp_send_head(sk)->skb_mstamp); | |
339 | else if (icsk->icsk_user_timeout && | |
340 | (s32)(tcp_time_stamp - start_ts) > icsk->icsk_user_timeout) | |
341 | goto abort; | |
1da177e4 | 342 | |
c6214a97 | 343 | max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2; |
1da177e4 | 344 | if (sock_flag(sk, SOCK_DEAD)) { |
7533ce30 | 345 | const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX; |
e905a9ed | 346 | |
1da177e4 | 347 | max_probes = tcp_orphan_retries(sk, alive); |
b248230c YC |
348 | if (!alive && icsk->icsk_backoff >= max_probes) |
349 | goto abort; | |
350 | if (tcp_out_of_resources(sk, true)) | |
1da177e4 LT |
351 | return; |
352 | } | |
353 | ||
6687e988 | 354 | if (icsk->icsk_probes_out > max_probes) { |
b248230c | 355 | abort: tcp_write_err(sk); |
1da177e4 LT |
356 | } else { |
357 | /* Only send another probe if we didn't close things up. */ | |
358 | tcp_send_probe0(sk); | |
359 | } | |
360 | } | |
361 | ||
8336886f JC |
362 | /* |
363 | * Timer for Fast Open socket to retransmit SYNACK. Note that the | |
364 | * sk here is the child socket, not the parent (listener) socket. | |
365 | */ | |
366 | static void tcp_fastopen_synack_timer(struct sock *sk) | |
367 | { | |
368 | struct inet_connection_sock *icsk = inet_csk(sk); | |
369 | int max_retries = icsk->icsk_syn_retries ? : | |
7c083ecb | 370 | sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */ |
8336886f JC |
371 | struct request_sock *req; |
372 | ||
373 | req = tcp_sk(sk)->fastopen_rsk; | |
42cb80a2 | 374 | req->rsk_ops->syn_ack_timeout(req); |
8336886f | 375 | |
e6c022a4 | 376 | if (req->num_timeout >= max_retries) { |
8336886f JC |
377 | tcp_write_err(sk); |
378 | return; | |
379 | } | |
380 | /* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error | |
381 | * returned from rtx_syn_ack() to make it more persistent like | |
382 | * regular retransmit because if the child socket has been accepted | |
383 | * it's not good to give up too easily. | |
384 | */ | |
e6c022a4 ED |
385 | inet_rtx_syn_ack(sk, req); |
386 | req->num_timeout++; | |
8336886f | 387 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
e6c022a4 | 388 | TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); |
8336886f JC |
389 | } |
390 | ||
1da177e4 | 391 | |
c380d37e RS |
392 | /** |
393 | * tcp_retransmit_timer() - The TCP retransmit timeout handler | |
394 | * @sk: Pointer to the current socket. | |
395 | * | |
396 | * This function gets called when the kernel timer for a TCP packet | |
397 | * of this socket expires. | |
398 | * | |
399 | * It handles retransmission, timer adjustment and other necesarry measures. | |
400 | * | |
401 | * Returns: Nothing (void) | |
402 | */ | |
f1ecd5d9 | 403 | void tcp_retransmit_timer(struct sock *sk) |
1da177e4 LT |
404 | { |
405 | struct tcp_sock *tp = tcp_sk(sk); | |
ae5c3f40 | 406 | struct net *net = sock_net(sk); |
463c84b9 | 407 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 408 | |
8336886f | 409 | if (tp->fastopen_rsk) { |
37561f68 JC |
410 | WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV && |
411 | sk->sk_state != TCP_FIN_WAIT1); | |
8336886f JC |
412 | tcp_fastopen_synack_timer(sk); |
413 | /* Before we receive ACK to our SYN-ACK don't retransmit | |
414 | * anything else (e.g., data or FIN segments). | |
415 | */ | |
416 | return; | |
417 | } | |
1da177e4 LT |
418 | if (!tp->packets_out) |
419 | goto out; | |
420 | ||
547b792c | 421 | WARN_ON(tcp_write_queue_empty(sk)); |
1da177e4 | 422 | |
9b717a8d ND |
423 | tp->tlp_high_seq = 0; |
424 | ||
1da177e4 LT |
425 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && |
426 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
427 | /* Receiver dastardly shrinks window. Our retransmits | |
428 | * become zero probes, but we should not timeout this | |
429 | * connection. If the socket is an orphan, time it out, | |
430 | * we cannot allow such beasts to hang infinitely. | |
431 | */ | |
569508c9 YH |
432 | struct inet_sock *inet = inet_sk(sk); |
433 | if (sk->sk_family == AF_INET) { | |
ba7a46f1 JP |
434 | net_dbg_ratelimited("Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
435 | &inet->inet_daddr, | |
436 | ntohs(inet->inet_dport), | |
437 | inet->inet_num, | |
438 | tp->snd_una, tp->snd_nxt); | |
1da177e4 | 439 | } |
dfd56b8b | 440 | #if IS_ENABLED(CONFIG_IPV6) |
569508c9 | 441 | else if (sk->sk_family == AF_INET6) { |
ba7a46f1 JP |
442 | net_dbg_ratelimited("Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
443 | &sk->sk_v6_daddr, | |
444 | ntohs(inet->inet_dport), | |
445 | inet->inet_num, | |
446 | tp->snd_una, tp->snd_nxt); | |
569508c9 | 447 | } |
1da177e4 LT |
448 | #endif |
449 | if (tcp_time_stamp - tp->rcv_tstamp > TCP_RTO_MAX) { | |
450 | tcp_write_err(sk); | |
451 | goto out; | |
452 | } | |
5ae344c9 | 453 | tcp_enter_loss(sk); |
10d3be56 | 454 | tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1); |
1da177e4 LT |
455 | __sk_dst_reset(sk); |
456 | goto out_reset_timer; | |
457 | } | |
458 | ||
459 | if (tcp_write_timeout(sk)) | |
460 | goto out; | |
461 | ||
463c84b9 | 462 | if (icsk->icsk_retransmits == 0) { |
40b215e5 PE |
463 | int mib_idx; |
464 | ||
c60ce4e2 | 465 | if (icsk->icsk_ca_state == TCP_CA_Recovery) { |
bc079e9e IJ |
466 | if (tcp_is_sack(tp)) |
467 | mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL; | |
468 | else | |
469 | mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL; | |
6687e988 | 470 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
40b215e5 | 471 | mib_idx = LINUX_MIB_TCPLOSSFAILURES; |
c60ce4e2 IJ |
472 | } else if ((icsk->icsk_ca_state == TCP_CA_Disorder) || |
473 | tp->sacked_out) { | |
474 | if (tcp_is_sack(tp)) | |
475 | mib_idx = LINUX_MIB_TCPSACKFAILURES; | |
476 | else | |
477 | mib_idx = LINUX_MIB_TCPRENOFAILURES; | |
1da177e4 | 478 | } else { |
40b215e5 | 479 | mib_idx = LINUX_MIB_TCPTIMEOUTS; |
1da177e4 | 480 | } |
02a1d6e7 | 481 | __NET_INC_STATS(sock_net(sk), mib_idx); |
1da177e4 LT |
482 | } |
483 | ||
5ae344c9 | 484 | tcp_enter_loss(sk); |
1da177e4 | 485 | |
10d3be56 | 486 | if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1) > 0) { |
1da177e4 LT |
487 | /* Retransmission failed because of local congestion, |
488 | * do not backoff. | |
489 | */ | |
463c84b9 ACM |
490 | if (!icsk->icsk_retransmits) |
491 | icsk->icsk_retransmits = 1; | |
492 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
493 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
494 | TCP_RTO_MAX); | |
1da177e4 LT |
495 | goto out; |
496 | } | |
497 | ||
498 | /* Increase the timeout each time we retransmit. Note that | |
499 | * we do not increase the rtt estimate. rto is initialized | |
500 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
501 | * that doubling rto each time is the least we can get away with. | |
502 | * In KA9Q, Karn uses this for the first few times, and then | |
503 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
504 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
505 | * defined in the protocol as the maximum possible RTT. I guess | |
506 | * we'll have to use something other than TCP to talk to the | |
507 | * University of Mars. | |
508 | * | |
509 | * PAWS allows us longer timeouts and large windows, so once | |
510 | * implemented ftp to mars will work nicely. We will have to fix | |
511 | * the 120 second clamps though! | |
512 | */ | |
463c84b9 ACM |
513 | icsk->icsk_backoff++; |
514 | icsk->icsk_retransmits++; | |
1da177e4 LT |
515 | |
516 | out_reset_timer: | |
36e31b0a AP |
517 | /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is |
518 | * used to reset timer, set to 0. Recalculate 'icsk_rto' as this | |
519 | * might be increased if the stream oscillates between thin and thick, | |
520 | * thus the old value might already be too high compared to the value | |
521 | * set by 'tcp_set_rto' in tcp_input.c which resets the rto without | |
522 | * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating | |
523 | * exponential backoff behaviour to avoid continue hammering | |
524 | * linear-timeout retransmissions into a black hole | |
525 | */ | |
526 | if (sk->sk_state == TCP_ESTABLISHED && | |
527 | (tp->thin_lto || sysctl_tcp_thin_linear_timeouts) && | |
528 | tcp_stream_is_thin(tp) && | |
529 | icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) { | |
530 | icsk->icsk_backoff = 0; | |
531 | icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX); | |
532 | } else { | |
533 | /* Use normal (exponential) backoff */ | |
534 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); | |
535 | } | |
3f421baa | 536 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX); |
ae5c3f40 | 537 | if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0, 0)) |
1da177e4 LT |
538 | __sk_dst_reset(sk); |
539 | ||
540 | out:; | |
541 | } | |
542 | ||
c380d37e RS |
543 | /* Called with bottom-half processing disabled. |
544 | Called by tcp_write_timer() */ | |
6f458dfb | 545 | void tcp_write_timer_handler(struct sock *sk) |
1da177e4 | 546 | { |
463c84b9 | 547 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
548 | int event; |
549 | ||
463c84b9 | 550 | if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending) |
1da177e4 LT |
551 | goto out; |
552 | ||
463c84b9 ACM |
553 | if (time_after(icsk->icsk_timeout, jiffies)) { |
554 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
555 | goto out; |
556 | } | |
557 | ||
463c84b9 | 558 | event = icsk->icsk_pending; |
1da177e4 LT |
559 | |
560 | switch (event) { | |
6ba8a3b1 ND |
561 | case ICSK_TIME_EARLY_RETRANS: |
562 | tcp_resume_early_retransmit(sk); | |
563 | break; | |
564 | case ICSK_TIME_LOSS_PROBE: | |
565 | tcp_send_loss_probe(sk); | |
566 | break; | |
463c84b9 | 567 | case ICSK_TIME_RETRANS: |
6ba8a3b1 | 568 | icsk->icsk_pending = 0; |
1da177e4 LT |
569 | tcp_retransmit_timer(sk); |
570 | break; | |
463c84b9 | 571 | case ICSK_TIME_PROBE0: |
6ba8a3b1 | 572 | icsk->icsk_pending = 0; |
1da177e4 LT |
573 | tcp_probe_timer(sk); |
574 | break; | |
575 | } | |
1da177e4 LT |
576 | |
577 | out: | |
3ab224be | 578 | sk_mem_reclaim(sk); |
6f458dfb ED |
579 | } |
580 | ||
581 | static void tcp_write_timer(unsigned long data) | |
582 | { | |
583 | struct sock *sk = (struct sock *)data; | |
584 | ||
585 | bh_lock_sock(sk); | |
586 | if (!sock_owned_by_user(sk)) { | |
587 | tcp_write_timer_handler(sk); | |
588 | } else { | |
c380d37e | 589 | /* delegate our work to tcp_release_cb() */ |
144d56e9 ED |
590 | if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags)) |
591 | sock_hold(sk); | |
6f458dfb | 592 | } |
1da177e4 LT |
593 | bh_unlock_sock(sk); |
594 | sock_put(sk); | |
595 | } | |
596 | ||
42cb80a2 | 597 | void tcp_syn_ack_timeout(const struct request_sock *req) |
72659ecc | 598 | { |
42cb80a2 ED |
599 | struct net *net = read_pnet(&inet_rsk(req)->ireq_net); |
600 | ||
02a1d6e7 | 601 | __NET_INC_STATS(net, LINUX_MIB_TCPTIMEOUTS); |
72659ecc OP |
602 | } |
603 | EXPORT_SYMBOL(tcp_syn_ack_timeout); | |
604 | ||
1da177e4 LT |
605 | void tcp_set_keepalive(struct sock *sk, int val) |
606 | { | |
607 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
608 | return; | |
609 | ||
610 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 611 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 612 | else if (!val) |
463c84b9 | 613 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 LT |
614 | } |
615 | ||
616 | ||
617 | static void tcp_keepalive_timer (unsigned long data) | |
618 | { | |
619 | struct sock *sk = (struct sock *) data; | |
6687e988 | 620 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 621 | struct tcp_sock *tp = tcp_sk(sk); |
6c37e5de | 622 | u32 elapsed; |
1da177e4 LT |
623 | |
624 | /* Only process if socket is not in use. */ | |
625 | bh_lock_sock(sk); | |
626 | if (sock_owned_by_user(sk)) { | |
e905a9ed | 627 | /* Try again later. */ |
463c84b9 | 628 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
629 | goto out; |
630 | } | |
631 | ||
632 | if (sk->sk_state == TCP_LISTEN) { | |
fa76ce73 | 633 | pr_err("Hmm... keepalive on a LISTEN ???\n"); |
1da177e4 LT |
634 | goto out; |
635 | } | |
636 | ||
637 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { | |
638 | if (tp->linger2 >= 0) { | |
463c84b9 | 639 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
640 | |
641 | if (tmo > 0) { | |
642 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
643 | goto out; | |
644 | } | |
645 | } | |
646 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
647 | goto death; | |
648 | } | |
649 | ||
650 | if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE) | |
651 | goto out; | |
652 | ||
653 | elapsed = keepalive_time_when(tp); | |
654 | ||
655 | /* It is alive without keepalive 8) */ | |
fe067e8a | 656 | if (tp->packets_out || tcp_send_head(sk)) |
1da177e4 LT |
657 | goto resched; |
658 | ||
6c37e5de | 659 | elapsed = keepalive_time_elapsed(tp); |
1da177e4 LT |
660 | |
661 | if (elapsed >= keepalive_time_when(tp)) { | |
dca43c75 JC |
662 | /* If the TCP_USER_TIMEOUT option is enabled, use that |
663 | * to determine when to timeout instead. | |
664 | */ | |
665 | if ((icsk->icsk_user_timeout != 0 && | |
666 | elapsed >= icsk->icsk_user_timeout && | |
667 | icsk->icsk_probes_out > 0) || | |
668 | (icsk->icsk_user_timeout == 0 && | |
669 | icsk->icsk_probes_out >= keepalive_probes(tp))) { | |
1da177e4 LT |
670 | tcp_send_active_reset(sk, GFP_ATOMIC); |
671 | tcp_write_err(sk); | |
672 | goto out; | |
673 | } | |
e520af48 | 674 | if (tcp_write_wakeup(sk, LINUX_MIB_TCPKEEPALIVE) <= 0) { |
6687e988 | 675 | icsk->icsk_probes_out++; |
1da177e4 LT |
676 | elapsed = keepalive_intvl_when(tp); |
677 | } else { | |
678 | /* If keepalive was lost due to local congestion, | |
679 | * try harder. | |
680 | */ | |
681 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
682 | } | |
683 | } else { | |
684 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
685 | elapsed = keepalive_time_when(tp) - elapsed; | |
686 | } | |
687 | ||
3ab224be | 688 | sk_mem_reclaim(sk); |
1da177e4 LT |
689 | |
690 | resched: | |
463c84b9 | 691 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
692 | goto out; |
693 | ||
e905a9ed | 694 | death: |
1da177e4 LT |
695 | tcp_done(sk); |
696 | ||
697 | out: | |
698 | bh_unlock_sock(sk); | |
699 | sock_put(sk); | |
700 | } | |
6f458dfb ED |
701 | |
702 | void tcp_init_xmit_timers(struct sock *sk) | |
703 | { | |
704 | inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer, | |
705 | &tcp_keepalive_timer); | |
706 | } |