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 | ||
55477206 | 25 | static u32 tcp_retransmit_stamp(const struct sock *sk) |
a7fa3770 JM |
26 | { |
27 | u32 start_ts = tcp_sk(sk)->retrans_stamp; | |
28 | ||
29 | if (unlikely(!start_ts)) { | |
30 | struct sk_buff *head = tcp_rtx_queue_head(sk); | |
31 | ||
32 | if (!head) | |
33 | return 0; | |
34 | start_ts = tcp_skb_timestamp(head); | |
35 | } | |
36 | return start_ts; | |
37 | } | |
38 | ||
b701a99e JM |
39 | static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk) |
40 | { | |
41 | struct inet_connection_sock *icsk = inet_csk(sk); | |
42 | u32 elapsed, start_ts; | |
43 | ||
44 | start_ts = tcp_retransmit_stamp(sk); | |
45 | if (!icsk->icsk_user_timeout || !start_ts) | |
46 | return icsk->icsk_rto; | |
47 | elapsed = tcp_time_stamp(tcp_sk(sk)) - start_ts; | |
48 | if (elapsed >= icsk->icsk_user_timeout) | |
49 | return 1; /* user timeout has passed; fire ASAP */ | |
50 | else | |
51 | return min_t(u32, icsk->icsk_rto, msecs_to_jiffies(icsk->icsk_user_timeout - elapsed)); | |
52 | } | |
53 | ||
c380d37e RS |
54 | /** |
55 | * tcp_write_err() - close socket and save error info | |
56 | * @sk: The socket the error has appeared on. | |
57 | * | |
58 | * Returns: Nothing (void) | |
59 | */ | |
60 | ||
1da177e4 LT |
61 | static void tcp_write_err(struct sock *sk) |
62 | { | |
63 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
64 | sk->sk_error_report(sk); | |
65 | ||
e05836ac | 66 | tcp_write_queue_purge(sk); |
1da177e4 | 67 | tcp_done(sk); |
02a1d6e7 | 68 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT); |
1da177e4 LT |
69 | } |
70 | ||
c380d37e RS |
71 | /** |
72 | * tcp_out_of_resources() - Close socket if out of resources | |
73 | * @sk: pointer to current socket | |
74 | * @do_reset: send a last packet with reset flag | |
1da177e4 | 75 | * |
c380d37e RS |
76 | * Do not allow orphaned sockets to eat all our resources. |
77 | * This is direct violation of TCP specs, but it is required | |
78 | * to prevent DoS attacks. It is called when a retransmission timeout | |
79 | * or zero probe timeout occurs on orphaned socket. | |
80 | * | |
4ee806d5 DS |
81 | * Also close if our net namespace is exiting; in that case there is no |
82 | * hope of ever communicating again since all netns interfaces are already | |
83 | * down (or about to be down), and we need to release our dst references, | |
84 | * which have been moved to the netns loopback interface, so the namespace | |
85 | * can finish exiting. This condition is only possible if we are a kernel | |
86 | * socket, as those do not hold references to the namespace. | |
87 | * | |
c380d37e RS |
88 | * Criteria is still not confirmed experimentally and may change. |
89 | * We kill the socket, if: | |
90 | * 1. If number of orphaned sockets exceeds an administratively configured | |
91 | * limit. | |
92 | * 2. If we have strong memory pressure. | |
4ee806d5 | 93 | * 3. If our net namespace is exiting. |
1da177e4 | 94 | */ |
b248230c | 95 | static int tcp_out_of_resources(struct sock *sk, bool do_reset) |
1da177e4 LT |
96 | { |
97 | struct tcp_sock *tp = tcp_sk(sk); | |
ad1af0fe | 98 | int shift = 0; |
1da177e4 | 99 | |
e905a9ed | 100 | /* If peer does not open window for long time, or did not transmit |
1da177e4 | 101 | * anything for long time, penalize it. */ |
d635fbe2 | 102 | if ((s32)(tcp_jiffies32 - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) |
ad1af0fe | 103 | shift++; |
1da177e4 LT |
104 | |
105 | /* If some dubious ICMP arrived, penalize even more. */ | |
106 | if (sk->sk_err_soft) | |
ad1af0fe | 107 | shift++; |
1da177e4 | 108 | |
efcdbf24 | 109 | if (tcp_check_oom(sk, shift)) { |
1da177e4 LT |
110 | /* Catch exceptional cases, when connection requires reset. |
111 | * 1. Last segment was sent recently. */ | |
d635fbe2 | 112 | if ((s32)(tcp_jiffies32 - tp->lsndtime) <= TCP_TIMEWAIT_LEN || |
1da177e4 LT |
113 | /* 2. Window is closed. */ |
114 | (!tp->snd_wnd && !tp->packets_out)) | |
b248230c | 115 | do_reset = true; |
1da177e4 LT |
116 | if (do_reset) |
117 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
118 | tcp_done(sk); | |
02a1d6e7 | 119 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); |
1da177e4 LT |
120 | return 1; |
121 | } | |
4ee806d5 DS |
122 | |
123 | if (!check_net(sock_net(sk))) { | |
124 | /* Not possible to send reset; just close */ | |
125 | tcp_done(sk); | |
126 | return 1; | |
127 | } | |
128 | ||
1da177e4 LT |
129 | return 0; |
130 | } | |
131 | ||
c380d37e RS |
132 | /** |
133 | * tcp_orphan_retries() - Returns maximal number of retries on an orphaned socket | |
134 | * @sk: Pointer to the current socket. | |
135 | * @alive: bool, socket alive state | |
136 | */ | |
7533ce30 | 137 | static int tcp_orphan_retries(struct sock *sk, bool alive) |
1da177e4 | 138 | { |
c402d9be | 139 | int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */ |
1da177e4 LT |
140 | |
141 | /* We know from an ICMP that something is wrong. */ | |
142 | if (sk->sk_err_soft && !alive) | |
143 | retries = 0; | |
144 | ||
145 | /* However, if socket sent something recently, select some safe | |
146 | * number of retries. 8 corresponds to >100 seconds with minimal | |
147 | * RTO of 200msec. */ | |
148 | if (retries == 0 && alive) | |
149 | retries = 8; | |
150 | return retries; | |
151 | } | |
152 | ||
ce55dd36 ED |
153 | static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) |
154 | { | |
d0f36847 ED |
155 | const struct net *net = sock_net(sk); |
156 | int mss; | |
b0f9ca53 | 157 | |
ce55dd36 | 158 | /* Black hole detection */ |
d0f36847 ED |
159 | if (!net->ipv4.sysctl_tcp_mtu_probing) |
160 | return; | |
161 | ||
162 | if (!icsk->icsk_mtup.enabled) { | |
163 | icsk->icsk_mtup.enabled = 1; | |
164 | icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; | |
165 | } else { | |
166 | mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; | |
167 | mss = min(net->ipv4.sysctl_tcp_base_mss, mss); | |
168 | mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len); | |
169 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
ce55dd36 | 170 | } |
d0f36847 | 171 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); |
ce55dd36 ED |
172 | } |
173 | ||
c380d37e RS |
174 | |
175 | /** | |
176 | * retransmits_timed_out() - returns true if this connection has timed out | |
177 | * @sk: The current socket | |
178 | * @boundary: max number of retransmissions | |
179 | * @timeout: A custom timeout value. | |
180 | * If set to 0 the default timeout is calculated and used. | |
181 | * Using TCP_RTO_MIN and the number of unsuccessful retransmits. | |
c380d37e RS |
182 | * |
183 | * The default "timeout" value this function can calculate and use | |
184 | * is equivalent to the timeout of a TCP Connection | |
185 | * after "boundary" unsuccessful, exponentially backed-off | |
ce682ef6 | 186 | * retransmissions with an initial RTO of TCP_RTO_MIN. |
2f7de571 DL |
187 | */ |
188 | static bool retransmits_timed_out(struct sock *sk, | |
dca43c75 | 189 | unsigned int boundary, |
ce682ef6 | 190 | unsigned int timeout) |
2f7de571 | 191 | { |
ce682ef6 | 192 | const unsigned int rto_base = TCP_RTO_MIN; |
9a568de4 | 193 | unsigned int linear_backoff_thresh, start_ts; |
2f7de571 DL |
194 | |
195 | if (!inet_csk(sk)->icsk_retransmits) | |
196 | return false; | |
197 | ||
a7fa3770 JM |
198 | start_ts = tcp_retransmit_stamp(sk); |
199 | if (!start_ts) | |
200 | return false; | |
2f7de571 | 201 | |
dca43c75 | 202 | if (likely(timeout == 0)) { |
21a180cd | 203 | linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base); |
2f7de571 | 204 | |
dca43c75 | 205 | if (boundary <= linear_backoff_thresh) |
21a180cd | 206 | timeout = ((2 << boundary) - 1) * rto_base; |
dca43c75 | 207 | else |
21a180cd | 208 | timeout = ((2 << linear_backoff_thresh) - 1) * rto_base + |
dca43c75 | 209 | (boundary - linear_backoff_thresh) * TCP_RTO_MAX; |
9bcc66e1 | 210 | timeout = jiffies_to_msecs(timeout); |
dca43c75 | 211 | } |
9bcc66e1 | 212 | return (tcp_time_stamp(tcp_sk(sk)) - start_ts) >= timeout; |
2f7de571 DL |
213 | } |
214 | ||
1da177e4 LT |
215 | /* A write timeout has occurred. Process the after effects. */ |
216 | static int tcp_write_timeout(struct sock *sk) | |
217 | { | |
5d424d5a | 218 | struct inet_connection_sock *icsk = inet_csk(sk); |
c968601d | 219 | struct tcp_sock *tp = tcp_sk(sk); |
6fa25166 | 220 | struct net *net = sock_net(sk); |
ce682ef6 | 221 | bool expired, do_reset; |
1da177e4 LT |
222 | int retry_until; |
223 | ||
224 | if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { | |
c968601d | 225 | if (icsk->icsk_retransmits) { |
b6c6712a | 226 | dst_negative_advice(sk); |
3acf3ec3 LB |
227 | } else if (!tp->syn_data && !tp->syn_fastopen) { |
228 | sk_rethink_txhash(sk); | |
c968601d | 229 | } |
6fa25166 | 230 | retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries; |
ce682ef6 | 231 | expired = icsk->icsk_retransmits >= retry_until; |
1da177e4 | 232 | } else { |
ce682ef6 | 233 | if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0)) { |
5d424d5a | 234 | /* Black hole detection */ |
ce55dd36 | 235 | tcp_mtu_probing(icsk, sk); |
1da177e4 | 236 | |
b6c6712a | 237 | dst_negative_advice(sk); |
3acf3ec3 LB |
238 | } else { |
239 | sk_rethink_txhash(sk); | |
1da177e4 LT |
240 | } |
241 | ||
c6214a97 | 242 | retry_until = net->ipv4.sysctl_tcp_retries2; |
1da177e4 | 243 | if (sock_flag(sk, SOCK_DEAD)) { |
7533ce30 | 244 | const bool alive = icsk->icsk_rto < TCP_RTO_MAX; |
e905a9ed | 245 | |
1da177e4 | 246 | retry_until = tcp_orphan_retries(sk, alive); |
6fa12c85 | 247 | do_reset = alive || |
ce682ef6 | 248 | !retransmits_timed_out(sk, retry_until, 0); |
1da177e4 | 249 | |
6fa12c85 | 250 | if (tcp_out_of_resources(sk, do_reset)) |
1da177e4 LT |
251 | return 1; |
252 | } | |
ce682ef6 ED |
253 | expired = retransmits_timed_out(sk, retry_until, |
254 | icsk->icsk_user_timeout); | |
1da177e4 | 255 | } |
7268586b | 256 | tcp_fastopen_active_detect_blackhole(sk, expired); |
f89013f6 LB |
257 | |
258 | if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG)) | |
259 | tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB, | |
260 | icsk->icsk_retransmits, | |
261 | icsk->icsk_rto, (int)expired); | |
262 | ||
ce682ef6 | 263 | if (expired) { |
1da177e4 LT |
264 | /* Has it gone just too far? */ |
265 | tcp_write_err(sk); | |
266 | return 1; | |
267 | } | |
f89013f6 | 268 | |
1da177e4 LT |
269 | return 0; |
270 | } | |
271 | ||
c10d9310 | 272 | /* Called with BH disabled */ |
6f458dfb | 273 | void tcp_delack_timer_handler(struct sock *sk) |
1da177e4 | 274 | { |
463c84b9 | 275 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 276 | |
9993e7d3 | 277 | sk_mem_reclaim_partial(sk); |
1da177e4 | 278 | |
02b2faaf ED |
279 | if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) || |
280 | !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) | |
1da177e4 LT |
281 | goto out; |
282 | ||
463c84b9 ACM |
283 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { |
284 | sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout); | |
1da177e4 LT |
285 | goto out; |
286 | } | |
463c84b9 | 287 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; |
1da177e4 | 288 | |
463c84b9 ACM |
289 | if (inet_csk_ack_scheduled(sk)) { |
290 | if (!icsk->icsk_ack.pingpong) { | |
1da177e4 | 291 | /* Delayed ACK missed: inflate ATO. */ |
463c84b9 | 292 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto); |
1da177e4 LT |
293 | } else { |
294 | /* Delayed ACK missed: leave pingpong mode and | |
295 | * deflate ATO. | |
296 | */ | |
463c84b9 ACM |
297 | icsk->icsk_ack.pingpong = 0; |
298 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 | 299 | } |
4688eb7c | 300 | tcp_mstamp_refresh(tcp_sk(sk)); |
1da177e4 | 301 | tcp_send_ack(sk); |
02a1d6e7 | 302 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS); |
1da177e4 | 303 | } |
1da177e4 LT |
304 | |
305 | out: | |
b8da51eb | 306 | if (tcp_under_memory_pressure(sk)) |
3ab224be | 307 | sk_mem_reclaim(sk); |
6f458dfb ED |
308 | } |
309 | ||
c380d37e RS |
310 | |
311 | /** | |
312 | * tcp_delack_timer() - The TCP delayed ACK timeout handler | |
313 | * @data: Pointer to the current socket. (gets casted to struct sock *) | |
314 | * | |
315 | * This function gets (indirectly) called when the kernel timer for a TCP packet | |
316 | * of this socket expires. Calls tcp_delack_timer_handler() to do the actual work. | |
317 | * | |
318 | * Returns: Nothing (void) | |
319 | */ | |
59f379f9 | 320 | static void tcp_delack_timer(struct timer_list *t) |
6f458dfb | 321 | { |
59f379f9 KC |
322 | struct inet_connection_sock *icsk = |
323 | from_timer(icsk, t, icsk_delack_timer); | |
324 | struct sock *sk = &icsk->icsk_inet.sk; | |
6f458dfb ED |
325 | |
326 | bh_lock_sock(sk); | |
327 | if (!sock_owned_by_user(sk)) { | |
328 | tcp_delack_timer_handler(sk); | |
329 | } else { | |
59f379f9 | 330 | icsk->icsk_ack.blocked = 1; |
02a1d6e7 | 331 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED); |
6f458dfb | 332 | /* deleguate our work to tcp_release_cb() */ |
7aa5470c | 333 | if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags)) |
144d56e9 | 334 | sock_hold(sk); |
6f458dfb | 335 | } |
1da177e4 LT |
336 | bh_unlock_sock(sk); |
337 | sock_put(sk); | |
338 | } | |
339 | ||
340 | static void tcp_probe_timer(struct sock *sk) | |
341 | { | |
6687e988 | 342 | struct inet_connection_sock *icsk = inet_csk(sk); |
75c119af | 343 | struct sk_buff *skb = tcp_send_head(sk); |
1da177e4 LT |
344 | struct tcp_sock *tp = tcp_sk(sk); |
345 | int max_probes; | |
b248230c | 346 | u32 start_ts; |
1da177e4 | 347 | |
75c119af | 348 | if (tp->packets_out || !skb) { |
6687e988 | 349 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
350 | return; |
351 | } | |
352 | ||
b248230c YC |
353 | /* RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as |
354 | * long as the receiver continues to respond probes. We support this by | |
355 | * default and reset icsk_probes_out with incoming ACKs. But if the | |
356 | * socket is orphaned or the user specifies TCP_USER_TIMEOUT, we | |
357 | * kill the socket when the retry count and the time exceeds the | |
358 | * corresponding system limit. We also implement similar policy when | |
359 | * we use RTO to probe window in tcp_retransmit_timer(). | |
1da177e4 | 360 | */ |
75c119af | 361 | start_ts = tcp_skb_timestamp(skb); |
b248230c | 362 | if (!start_ts) |
5f6188a8 | 363 | skb->skb_mstamp_ns = tp->tcp_clock_cache; |
b248230c | 364 | else if (icsk->icsk_user_timeout && |
9bcc66e1 | 365 | (s32)(tcp_time_stamp(tp) - start_ts) > icsk->icsk_user_timeout) |
b248230c | 366 | goto abort; |
1da177e4 | 367 | |
c6214a97 | 368 | max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2; |
1da177e4 | 369 | if (sock_flag(sk, SOCK_DEAD)) { |
7533ce30 | 370 | const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX; |
e905a9ed | 371 | |
1da177e4 | 372 | max_probes = tcp_orphan_retries(sk, alive); |
b248230c YC |
373 | if (!alive && icsk->icsk_backoff >= max_probes) |
374 | goto abort; | |
375 | if (tcp_out_of_resources(sk, true)) | |
1da177e4 LT |
376 | return; |
377 | } | |
378 | ||
6687e988 | 379 | if (icsk->icsk_probes_out > max_probes) { |
b248230c | 380 | abort: tcp_write_err(sk); |
1da177e4 LT |
381 | } else { |
382 | /* Only send another probe if we didn't close things up. */ | |
383 | tcp_send_probe0(sk); | |
384 | } | |
385 | } | |
386 | ||
8336886f JC |
387 | /* |
388 | * Timer for Fast Open socket to retransmit SYNACK. Note that the | |
389 | * sk here is the child socket, not the parent (listener) socket. | |
390 | */ | |
391 | static void tcp_fastopen_synack_timer(struct sock *sk) | |
392 | { | |
393 | struct inet_connection_sock *icsk = inet_csk(sk); | |
394 | int max_retries = icsk->icsk_syn_retries ? : | |
7c083ecb | 395 | sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */ |
8336886f JC |
396 | struct request_sock *req; |
397 | ||
398 | req = tcp_sk(sk)->fastopen_rsk; | |
42cb80a2 | 399 | req->rsk_ops->syn_ack_timeout(req); |
8336886f | 400 | |
e6c022a4 | 401 | if (req->num_timeout >= max_retries) { |
8336886f JC |
402 | tcp_write_err(sk); |
403 | return; | |
404 | } | |
405 | /* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error | |
406 | * returned from rtx_syn_ack() to make it more persistent like | |
407 | * regular retransmit because if the child socket has been accepted | |
408 | * it's not good to give up too easily. | |
409 | */ | |
e6c022a4 ED |
410 | inet_rtx_syn_ack(sk, req); |
411 | req->num_timeout++; | |
7e32b443 | 412 | icsk->icsk_retransmits++; |
8336886f | 413 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
e6c022a4 | 414 | TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); |
8336886f JC |
415 | } |
416 | ||
1da177e4 | 417 | |
c380d37e RS |
418 | /** |
419 | * tcp_retransmit_timer() - The TCP retransmit timeout handler | |
420 | * @sk: Pointer to the current socket. | |
421 | * | |
422 | * This function gets called when the kernel timer for a TCP packet | |
423 | * of this socket expires. | |
424 | * | |
425 | * It handles retransmission, timer adjustment and other necesarry measures. | |
426 | * | |
427 | * Returns: Nothing (void) | |
428 | */ | |
f1ecd5d9 | 429 | void tcp_retransmit_timer(struct sock *sk) |
1da177e4 LT |
430 | { |
431 | struct tcp_sock *tp = tcp_sk(sk); | |
ae5c3f40 | 432 | struct net *net = sock_net(sk); |
463c84b9 | 433 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 434 | |
8336886f | 435 | if (tp->fastopen_rsk) { |
37561f68 JC |
436 | WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV && |
437 | sk->sk_state != TCP_FIN_WAIT1); | |
8336886f JC |
438 | tcp_fastopen_synack_timer(sk); |
439 | /* Before we receive ACK to our SYN-ACK don't retransmit | |
440 | * anything else (e.g., data or FIN segments). | |
441 | */ | |
442 | return; | |
443 | } | |
1da177e4 LT |
444 | if (!tp->packets_out) |
445 | goto out; | |
446 | ||
75c119af | 447 | WARN_ON(tcp_rtx_queue_empty(sk)); |
1da177e4 | 448 | |
9b717a8d ND |
449 | tp->tlp_high_seq = 0; |
450 | ||
1da177e4 LT |
451 | if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) && |
452 | !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) { | |
453 | /* Receiver dastardly shrinks window. Our retransmits | |
454 | * become zero probes, but we should not timeout this | |
455 | * connection. If the socket is an orphan, time it out, | |
456 | * we cannot allow such beasts to hang infinitely. | |
457 | */ | |
569508c9 YH |
458 | struct inet_sock *inet = inet_sk(sk); |
459 | if (sk->sk_family == AF_INET) { | |
ba7a46f1 JP |
460 | net_dbg_ratelimited("Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
461 | &inet->inet_daddr, | |
462 | ntohs(inet->inet_dport), | |
463 | inet->inet_num, | |
464 | tp->snd_una, tp->snd_nxt); | |
1da177e4 | 465 | } |
dfd56b8b | 466 | #if IS_ENABLED(CONFIG_IPV6) |
569508c9 | 467 | else if (sk->sk_family == AF_INET6) { |
ba7a46f1 JP |
468 | net_dbg_ratelimited("Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n", |
469 | &sk->sk_v6_daddr, | |
470 | ntohs(inet->inet_dport), | |
471 | inet->inet_num, | |
472 | tp->snd_una, tp->snd_nxt); | |
569508c9 | 473 | } |
1da177e4 | 474 | #endif |
70eabf0e | 475 | if (tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX) { |
1da177e4 LT |
476 | tcp_write_err(sk); |
477 | goto out; | |
478 | } | |
5ae344c9 | 479 | tcp_enter_loss(sk); |
75c119af | 480 | tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1); |
1da177e4 LT |
481 | __sk_dst_reset(sk); |
482 | goto out_reset_timer; | |
483 | } | |
484 | ||
485 | if (tcp_write_timeout(sk)) | |
486 | goto out; | |
487 | ||
463c84b9 | 488 | if (icsk->icsk_retransmits == 0) { |
40b215e5 PE |
489 | int mib_idx; |
490 | ||
c60ce4e2 | 491 | if (icsk->icsk_ca_state == TCP_CA_Recovery) { |
bc079e9e IJ |
492 | if (tcp_is_sack(tp)) |
493 | mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL; | |
494 | else | |
495 | mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL; | |
6687e988 | 496 | } else if (icsk->icsk_ca_state == TCP_CA_Loss) { |
40b215e5 | 497 | mib_idx = LINUX_MIB_TCPLOSSFAILURES; |
c60ce4e2 IJ |
498 | } else if ((icsk->icsk_ca_state == TCP_CA_Disorder) || |
499 | tp->sacked_out) { | |
500 | if (tcp_is_sack(tp)) | |
501 | mib_idx = LINUX_MIB_TCPSACKFAILURES; | |
502 | else | |
503 | mib_idx = LINUX_MIB_TCPRENOFAILURES; | |
1da177e4 | 504 | } else { |
40b215e5 | 505 | mib_idx = LINUX_MIB_TCPTIMEOUTS; |
1da177e4 | 506 | } |
02a1d6e7 | 507 | __NET_INC_STATS(sock_net(sk), mib_idx); |
1da177e4 LT |
508 | } |
509 | ||
5ae344c9 | 510 | tcp_enter_loss(sk); |
1da177e4 | 511 | |
75c119af | 512 | if (tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1) > 0) { |
1da177e4 LT |
513 | /* Retransmission failed because of local congestion, |
514 | * do not backoff. | |
515 | */ | |
463c84b9 ACM |
516 | if (!icsk->icsk_retransmits) |
517 | icsk->icsk_retransmits = 1; | |
518 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3f421baa ACM |
519 | min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), |
520 | TCP_RTO_MAX); | |
1da177e4 LT |
521 | goto out; |
522 | } | |
523 | ||
524 | /* Increase the timeout each time we retransmit. Note that | |
525 | * we do not increase the rtt estimate. rto is initialized | |
526 | * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests | |
527 | * that doubling rto each time is the least we can get away with. | |
528 | * In KA9Q, Karn uses this for the first few times, and then | |
529 | * goes to quadratic. netBSD doubles, but only goes up to *64, | |
530 | * and clamps at 1 to 64 sec afterwards. Note that 120 sec is | |
531 | * defined in the protocol as the maximum possible RTT. I guess | |
532 | * we'll have to use something other than TCP to talk to the | |
533 | * University of Mars. | |
534 | * | |
535 | * PAWS allows us longer timeouts and large windows, so once | |
536 | * implemented ftp to mars will work nicely. We will have to fix | |
537 | * the 120 second clamps though! | |
538 | */ | |
463c84b9 ACM |
539 | icsk->icsk_backoff++; |
540 | icsk->icsk_retransmits++; | |
1da177e4 LT |
541 | |
542 | out_reset_timer: | |
36e31b0a AP |
543 | /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is |
544 | * used to reset timer, set to 0. Recalculate 'icsk_rto' as this | |
545 | * might be increased if the stream oscillates between thin and thick, | |
546 | * thus the old value might already be too high compared to the value | |
547 | * set by 'tcp_set_rto' in tcp_input.c which resets the rto without | |
548 | * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating | |
549 | * exponential backoff behaviour to avoid continue hammering | |
550 | * linear-timeout retransmissions into a black hole | |
551 | */ | |
552 | if (sk->sk_state == TCP_ESTABLISHED && | |
2c04ac8a | 553 | (tp->thin_lto || net->ipv4.sysctl_tcp_thin_linear_timeouts) && |
36e31b0a AP |
554 | tcp_stream_is_thin(tp) && |
555 | icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) { | |
556 | icsk->icsk_backoff = 0; | |
557 | icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX); | |
558 | } else { | |
559 | /* Use normal (exponential) backoff */ | |
560 | icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX); | |
561 | } | |
b701a99e JM |
562 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
563 | tcp_clamp_rto_to_user_timeout(sk), TCP_RTO_MAX); | |
ce682ef6 | 564 | if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0)) |
1da177e4 LT |
565 | __sk_dst_reset(sk); |
566 | ||
567 | out:; | |
568 | } | |
569 | ||
c380d37e RS |
570 | /* Called with bottom-half processing disabled. |
571 | Called by tcp_write_timer() */ | |
6f458dfb | 572 | void tcp_write_timer_handler(struct sock *sk) |
1da177e4 | 573 | { |
463c84b9 | 574 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
575 | int event; |
576 | ||
02b2faaf ED |
577 | if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) || |
578 | !icsk->icsk_pending) | |
1da177e4 LT |
579 | goto out; |
580 | ||
463c84b9 ACM |
581 | if (time_after(icsk->icsk_timeout, jiffies)) { |
582 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout); | |
1da177e4 LT |
583 | goto out; |
584 | } | |
585 | ||
9a568de4 | 586 | tcp_mstamp_refresh(tcp_sk(sk)); |
463c84b9 | 587 | event = icsk->icsk_pending; |
1da177e4 LT |
588 | |
589 | switch (event) { | |
57dde7f7 YC |
590 | case ICSK_TIME_REO_TIMEOUT: |
591 | tcp_rack_reo_timeout(sk); | |
592 | break; | |
6ba8a3b1 ND |
593 | case ICSK_TIME_LOSS_PROBE: |
594 | tcp_send_loss_probe(sk); | |
595 | break; | |
463c84b9 | 596 | case ICSK_TIME_RETRANS: |
6ba8a3b1 | 597 | icsk->icsk_pending = 0; |
1da177e4 LT |
598 | tcp_retransmit_timer(sk); |
599 | break; | |
463c84b9 | 600 | case ICSK_TIME_PROBE0: |
6ba8a3b1 | 601 | icsk->icsk_pending = 0; |
1da177e4 LT |
602 | tcp_probe_timer(sk); |
603 | break; | |
604 | } | |
1da177e4 LT |
605 | |
606 | out: | |
3ab224be | 607 | sk_mem_reclaim(sk); |
6f458dfb ED |
608 | } |
609 | ||
59f379f9 | 610 | static void tcp_write_timer(struct timer_list *t) |
6f458dfb | 611 | { |
59f379f9 KC |
612 | struct inet_connection_sock *icsk = |
613 | from_timer(icsk, t, icsk_retransmit_timer); | |
614 | struct sock *sk = &icsk->icsk_inet.sk; | |
6f458dfb ED |
615 | |
616 | bh_lock_sock(sk); | |
617 | if (!sock_owned_by_user(sk)) { | |
618 | tcp_write_timer_handler(sk); | |
619 | } else { | |
c380d37e | 620 | /* delegate our work to tcp_release_cb() */ |
7aa5470c | 621 | if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &sk->sk_tsq_flags)) |
144d56e9 | 622 | sock_hold(sk); |
6f458dfb | 623 | } |
1da177e4 LT |
624 | bh_unlock_sock(sk); |
625 | sock_put(sk); | |
626 | } | |
627 | ||
42cb80a2 | 628 | void tcp_syn_ack_timeout(const struct request_sock *req) |
72659ecc | 629 | { |
42cb80a2 ED |
630 | struct net *net = read_pnet(&inet_rsk(req)->ireq_net); |
631 | ||
02a1d6e7 | 632 | __NET_INC_STATS(net, LINUX_MIB_TCPTIMEOUTS); |
72659ecc OP |
633 | } |
634 | EXPORT_SYMBOL(tcp_syn_ack_timeout); | |
635 | ||
1da177e4 LT |
636 | void tcp_set_keepalive(struct sock *sk, int val) |
637 | { | |
638 | if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) | |
639 | return; | |
640 | ||
641 | if (val && !sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 642 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk))); |
1da177e4 | 643 | else if (!val) |
463c84b9 | 644 | inet_csk_delete_keepalive_timer(sk); |
1da177e4 | 645 | } |
4b9d07a4 | 646 | EXPORT_SYMBOL_GPL(tcp_set_keepalive); |
1da177e4 LT |
647 | |
648 | ||
59f379f9 | 649 | static void tcp_keepalive_timer (struct timer_list *t) |
1da177e4 | 650 | { |
59f379f9 | 651 | struct sock *sk = from_timer(sk, t, sk_timer); |
6687e988 | 652 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 653 | struct tcp_sock *tp = tcp_sk(sk); |
6c37e5de | 654 | u32 elapsed; |
1da177e4 LT |
655 | |
656 | /* Only process if socket is not in use. */ | |
657 | bh_lock_sock(sk); | |
658 | if (sock_owned_by_user(sk)) { | |
e905a9ed | 659 | /* Try again later. */ |
463c84b9 | 660 | inet_csk_reset_keepalive_timer (sk, HZ/20); |
1da177e4 LT |
661 | goto out; |
662 | } | |
663 | ||
664 | if (sk->sk_state == TCP_LISTEN) { | |
fa76ce73 | 665 | pr_err("Hmm... keepalive on a LISTEN ???\n"); |
1da177e4 LT |
666 | goto out; |
667 | } | |
668 | ||
4688eb7c | 669 | tcp_mstamp_refresh(tp); |
1da177e4 LT |
670 | if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) { |
671 | if (tp->linger2 >= 0) { | |
463c84b9 | 672 | const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN; |
1da177e4 LT |
673 | |
674 | if (tmo > 0) { | |
675 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
676 | goto out; | |
677 | } | |
678 | } | |
679 | tcp_send_active_reset(sk, GFP_ATOMIC); | |
680 | goto death; | |
681 | } | |
682 | ||
2dda6400 ED |
683 | if (!sock_flag(sk, SOCK_KEEPOPEN) || |
684 | ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT))) | |
1da177e4 LT |
685 | goto out; |
686 | ||
687 | elapsed = keepalive_time_when(tp); | |
688 | ||
689 | /* It is alive without keepalive 8) */ | |
75c119af | 690 | if (tp->packets_out || !tcp_write_queue_empty(sk)) |
1da177e4 LT |
691 | goto resched; |
692 | ||
6c37e5de | 693 | elapsed = keepalive_time_elapsed(tp); |
1da177e4 LT |
694 | |
695 | if (elapsed >= keepalive_time_when(tp)) { | |
dca43c75 JC |
696 | /* If the TCP_USER_TIMEOUT option is enabled, use that |
697 | * to determine when to timeout instead. | |
698 | */ | |
699 | if ((icsk->icsk_user_timeout != 0 && | |
9bcc66e1 | 700 | elapsed >= msecs_to_jiffies(icsk->icsk_user_timeout) && |
dca43c75 JC |
701 | icsk->icsk_probes_out > 0) || |
702 | (icsk->icsk_user_timeout == 0 && | |
703 | icsk->icsk_probes_out >= keepalive_probes(tp))) { | |
1da177e4 LT |
704 | tcp_send_active_reset(sk, GFP_ATOMIC); |
705 | tcp_write_err(sk); | |
706 | goto out; | |
707 | } | |
e520af48 | 708 | if (tcp_write_wakeup(sk, LINUX_MIB_TCPKEEPALIVE) <= 0) { |
6687e988 | 709 | icsk->icsk_probes_out++; |
1da177e4 LT |
710 | elapsed = keepalive_intvl_when(tp); |
711 | } else { | |
712 | /* If keepalive was lost due to local congestion, | |
713 | * try harder. | |
714 | */ | |
715 | elapsed = TCP_RESOURCE_PROBE_INTERVAL; | |
716 | } | |
717 | } else { | |
718 | /* It is tp->rcv_tstamp + keepalive_time_when(tp) */ | |
719 | elapsed = keepalive_time_when(tp) - elapsed; | |
720 | } | |
721 | ||
3ab224be | 722 | sk_mem_reclaim(sk); |
1da177e4 LT |
723 | |
724 | resched: | |
463c84b9 | 725 | inet_csk_reset_keepalive_timer (sk, elapsed); |
1da177e4 LT |
726 | goto out; |
727 | ||
e905a9ed | 728 | death: |
1da177e4 LT |
729 | tcp_done(sk); |
730 | ||
731 | out: | |
732 | bh_unlock_sock(sk); | |
733 | sock_put(sk); | |
734 | } | |
6f458dfb | 735 | |
5d9f4262 ED |
736 | static enum hrtimer_restart tcp_compressed_ack_kick(struct hrtimer *timer) |
737 | { | |
738 | struct tcp_sock *tp = container_of(timer, struct tcp_sock, compressed_ack_timer); | |
739 | struct sock *sk = (struct sock *)tp; | |
740 | ||
741 | bh_lock_sock(sk); | |
742 | if (!sock_owned_by_user(sk)) { | |
743 | if (tp->compressed_ack) | |
744 | tcp_send_ack(sk); | |
745 | } else { | |
746 | if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, | |
747 | &sk->sk_tsq_flags)) | |
748 | sock_hold(sk); | |
749 | } | |
750 | bh_unlock_sock(sk); | |
751 | ||
752 | sock_put(sk); | |
753 | ||
754 | return HRTIMER_NORESTART; | |
755 | } | |
756 | ||
6f458dfb ED |
757 | void tcp_init_xmit_timers(struct sock *sk) |
758 | { | |
759 | inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer, | |
760 | &tcp_keepalive_timer); | |
fb420d5d | 761 | hrtimer_init(&tcp_sk(sk)->pacing_timer, CLOCK_MONOTONIC, |
73a6bab5 | 762 | HRTIMER_MODE_ABS_PINNED_SOFT); |
218af599 | 763 | tcp_sk(sk)->pacing_timer.function = tcp_pace_kick; |
5d9f4262 ED |
764 | |
765 | hrtimer_init(&tcp_sk(sk)->compressed_ack_timer, CLOCK_MONOTONIC, | |
766 | HRTIMER_MODE_REL_PINNED_SOFT); | |
767 | tcp_sk(sk)->compressed_ack_timer.function = tcp_compressed_ack_kick; | |
6f458dfb | 768 | } |