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1/*
2 * net/dccp/timer.c
3 *
4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13#include <linux/dccp.h>
14#include <linux/skbuff.h>
15
16#include "dccp.h"
17
18/* sysctl variables governing numbers of retransmission attempts */
19int sysctl_dccp_request_retries __read_mostly = TCP_SYN_RETRIES;
20int sysctl_dccp_retries1 __read_mostly = TCP_RETR1;
21int sysctl_dccp_retries2 __read_mostly = TCP_RETR2;
22
23static void dccp_write_err(struct sock *sk)
24{
25 sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
26 sk->sk_error_report(sk);
27
28 dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
29 dccp_done(sk);
30 DCCP_INC_STATS_BH(DCCP_MIB_ABORTONTIMEOUT);
31}
32
33/* A write timeout has occurred. Process the after effects. */
34static int dccp_write_timeout(struct sock *sk)
35{
36 const struct inet_connection_sock *icsk = inet_csk(sk);
37 int retry_until;
38
39 if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) {
40 if (icsk->icsk_retransmits != 0)
41 dst_negative_advice(sk);
42 retry_until = icsk->icsk_syn_retries ?
43 : sysctl_dccp_request_retries;
44 } else {
45 if (icsk->icsk_retransmits >= sysctl_dccp_retries1) {
46 /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu
47 black hole detection. :-(
48
49 It is place to make it. It is not made. I do not want
50 to make it. It is disguisting. It does not work in any
51 case. Let me to cite the same draft, which requires for
52 us to implement this:
53
54 "The one security concern raised by this memo is that ICMP black holes
55 are often caused by over-zealous security administrators who block
56 all ICMP messages. It is vitally important that those who design and
57 deploy security systems understand the impact of strict filtering on
58 upper-layer protocols. The safest web site in the world is worthless
59 if most TCP implementations cannot transfer data from it. It would
60 be far nicer to have all of the black holes fixed rather than fixing
61 all of the TCP implementations."
62
63 Golden words :-).
64 */
65
66 dst_negative_advice(sk);
67 }
68
69 retry_until = sysctl_dccp_retries2;
70 /*
71 * FIXME: see tcp_write_timout and tcp_out_of_resources
72 */
73 }
74
75 if (icsk->icsk_retransmits >= retry_until) {
76 /* Has it gone just too far? */
77 dccp_write_err(sk);
78 return 1;
79 }
80 return 0;
81}
82
83/*
84 * The DCCP retransmit timer.
85 */
86static void dccp_retransmit_timer(struct sock *sk)
87{
88 struct inet_connection_sock *icsk = inet_csk(sk);
89
90 /*
91 * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
92 * sent, no need to retransmit, this sock is dead.
93 */
94 if (dccp_write_timeout(sk))
95 return;
96
97 /*
98 * We want to know the number of packets retransmitted, not the
99 * total number of retransmissions of clones of original packets.
100 */
101 if (icsk->icsk_retransmits == 0)
102 DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
103
104 if (dccp_retransmit_skb(sk) != 0) {
105 /*
106 * Retransmission failed because of local congestion,
107 * do not backoff.
108 */
109 if (--icsk->icsk_retransmits == 0)
110 icsk->icsk_retransmits = 1;
111 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
112 min(icsk->icsk_rto,
113 TCP_RESOURCE_PROBE_INTERVAL),
114 DCCP_RTO_MAX);
115 return;
116 }
117
118 icsk->icsk_backoff++;
119
120 icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
121 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
122 DCCP_RTO_MAX);
123 if (icsk->icsk_retransmits > sysctl_dccp_retries1)
124 __sk_dst_reset(sk);
125}
126
127static void dccp_write_timer(unsigned long data)
128{
129 struct sock *sk = (struct sock *)data;
130 struct inet_connection_sock *icsk = inet_csk(sk);
131 int event = 0;
132
133 bh_lock_sock(sk);
134 if (sock_owned_by_user(sk)) {
135 /* Try again later */
136 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
137 jiffies + (HZ / 20));
138 goto out;
139 }
140
141 if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending)
142 goto out;
143
144 if (time_after(icsk->icsk_timeout, jiffies)) {
145 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
146 icsk->icsk_timeout);
147 goto out;
148 }
149
150 event = icsk->icsk_pending;
151 icsk->icsk_pending = 0;
152
153 switch (event) {
154 case ICSK_TIME_RETRANS:
155 dccp_retransmit_timer(sk);
156 break;
157 }
158out:
159 bh_unlock_sock(sk);
160 sock_put(sk);
161}
162
163/*
164 * Timer for listening sockets
165 */
166static void dccp_response_timer(struct sock *sk)
167{
168 inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, DCCP_TIMEOUT_INIT,
169 DCCP_RTO_MAX);
170}
171
172static void dccp_keepalive_timer(unsigned long data)
173{
174 struct sock *sk = (struct sock *)data;
175
176 /* Only process if socket is not in use. */
177 bh_lock_sock(sk);
178 if (sock_owned_by_user(sk)) {
179 /* Try again later. */
180 inet_csk_reset_keepalive_timer(sk, HZ / 20);
181 goto out;
182 }
183
184 if (sk->sk_state == DCCP_LISTEN) {
185 dccp_response_timer(sk);
186 goto out;
187 }
188out:
189 bh_unlock_sock(sk);
190 sock_put(sk);
191}
192
193/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
194static void dccp_delack_timer(unsigned long data)
195{
196 struct sock *sk = (struct sock *)data;
197 struct inet_connection_sock *icsk = inet_csk(sk);
198
199 bh_lock_sock(sk);
200 if (sock_owned_by_user(sk)) {
201 /* Try again later. */
202 icsk->icsk_ack.blocked = 1;
203 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
204 sk_reset_timer(sk, &icsk->icsk_delack_timer,
205 jiffies + TCP_DELACK_MIN);
206 goto out;
207 }
208
209 if (sk->sk_state == DCCP_CLOSED ||
210 !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
211 goto out;
212 if (time_after(icsk->icsk_ack.timeout, jiffies)) {
213 sk_reset_timer(sk, &icsk->icsk_delack_timer,
214 icsk->icsk_ack.timeout);
215 goto out;
216 }
217
218 icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
219
220 if (inet_csk_ack_scheduled(sk)) {
221 if (!icsk->icsk_ack.pingpong) {
222 /* Delayed ACK missed: inflate ATO. */
223 icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
224 icsk->icsk_rto);
225 } else {
226 /* Delayed ACK missed: leave pingpong mode and
227 * deflate ATO.
228 */
229 icsk->icsk_ack.pingpong = 0;
230 icsk->icsk_ack.ato = TCP_ATO_MIN;
231 }
232 dccp_send_ack(sk);
233 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS);
234 }
235out:
236 bh_unlock_sock(sk);
237 sock_put(sk);
238}
239
240/**
241 * dccp_write_xmitlet - Workhorse for CCID packet dequeueing interface
242 * See the comments above %ccid_dequeueing_decision for supported modes.
243 */
244static void dccp_write_xmitlet(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 sk_reset_timer(sk, &dccp_sk(sk)->dccps_xmit_timer, jiffies + 1);
251 else
252 dccp_write_xmit(sk);
253 bh_unlock_sock(sk);
254}
255
256static void dccp_write_xmit_timer(unsigned long data)
257{
258 dccp_write_xmitlet(data);
259 sock_put((struct sock *)data);
260}
261
262void dccp_init_xmit_timers(struct sock *sk)
263{
264 struct dccp_sock *dp = dccp_sk(sk);
265
266 tasklet_init(&dp->dccps_xmitlet, dccp_write_xmitlet, (unsigned long)sk);
267 setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer,
268 (unsigned long)sk);
269 inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
270 &dccp_keepalive_timer);
271}
272
273static ktime_t dccp_timestamp_seed;
274/**
275 * dccp_timestamp - 10s of microseconds time source
276 * Returns the number of 10s of microseconds since loading DCCP. This is native
277 * DCCP time difference format (RFC 4340, sec. 13).
278 * Please note: This will wrap around about circa every 11.9 hours.
279 */
280u32 dccp_timestamp(void)
281{
282 s64 delta = ktime_us_delta(ktime_get_real(), dccp_timestamp_seed);
283
284 do_div(delta, 10);
285 return delta;
286}
287EXPORT_SYMBOL_GPL(dccp_timestamp);
288
289void __init dccp_timestamping_init(void)
290{
291 dccp_timestamp_seed = ktime_get_real();
292}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/dccp/timer.c
4 *
5 * An implementation of the DCCP protocol
6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 */
8
9#include <linux/dccp.h>
10#include <linux/skbuff.h>
11#include <linux/export.h>
12
13#include "dccp.h"
14
15/* sysctl variables governing numbers of retransmission attempts */
16int sysctl_dccp_request_retries __read_mostly = TCP_SYN_RETRIES;
17int sysctl_dccp_retries1 __read_mostly = TCP_RETR1;
18int sysctl_dccp_retries2 __read_mostly = TCP_RETR2;
19
20static void dccp_write_err(struct sock *sk)
21{
22 sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
23 sk->sk_error_report(sk);
24
25 dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
26 dccp_done(sk);
27 __DCCP_INC_STATS(DCCP_MIB_ABORTONTIMEOUT);
28}
29
30/* A write timeout has occurred. Process the after effects. */
31static int dccp_write_timeout(struct sock *sk)
32{
33 const struct inet_connection_sock *icsk = inet_csk(sk);
34 int retry_until;
35
36 if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) {
37 if (icsk->icsk_retransmits != 0)
38 dst_negative_advice(sk);
39 retry_until = icsk->icsk_syn_retries ?
40 : sysctl_dccp_request_retries;
41 } else {
42 if (icsk->icsk_retransmits >= sysctl_dccp_retries1) {
43 /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu
44 black hole detection. :-(
45
46 It is place to make it. It is not made. I do not want
47 to make it. It is disguisting. It does not work in any
48 case. Let me to cite the same draft, which requires for
49 us to implement this:
50
51 "The one security concern raised by this memo is that ICMP black holes
52 are often caused by over-zealous security administrators who block
53 all ICMP messages. It is vitally important that those who design and
54 deploy security systems understand the impact of strict filtering on
55 upper-layer protocols. The safest web site in the world is worthless
56 if most TCP implementations cannot transfer data from it. It would
57 be far nicer to have all of the black holes fixed rather than fixing
58 all of the TCP implementations."
59
60 Golden words :-).
61 */
62
63 dst_negative_advice(sk);
64 }
65
66 retry_until = sysctl_dccp_retries2;
67 /*
68 * FIXME: see tcp_write_timout and tcp_out_of_resources
69 */
70 }
71
72 if (icsk->icsk_retransmits >= retry_until) {
73 /* Has it gone just too far? */
74 dccp_write_err(sk);
75 return 1;
76 }
77 return 0;
78}
79
80/*
81 * The DCCP retransmit timer.
82 */
83static void dccp_retransmit_timer(struct sock *sk)
84{
85 struct inet_connection_sock *icsk = inet_csk(sk);
86
87 /*
88 * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
89 * sent, no need to retransmit, this sock is dead.
90 */
91 if (dccp_write_timeout(sk))
92 return;
93
94 /*
95 * We want to know the number of packets retransmitted, not the
96 * total number of retransmissions of clones of original packets.
97 */
98 if (icsk->icsk_retransmits == 0)
99 __DCCP_INC_STATS(DCCP_MIB_TIMEOUTS);
100
101 if (dccp_retransmit_skb(sk) != 0) {
102 /*
103 * Retransmission failed because of local congestion,
104 * do not backoff.
105 */
106 if (--icsk->icsk_retransmits == 0)
107 icsk->icsk_retransmits = 1;
108 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
109 min(icsk->icsk_rto,
110 TCP_RESOURCE_PROBE_INTERVAL),
111 DCCP_RTO_MAX);
112 return;
113 }
114
115 icsk->icsk_backoff++;
116
117 icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
118 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
119 DCCP_RTO_MAX);
120 if (icsk->icsk_retransmits > sysctl_dccp_retries1)
121 __sk_dst_reset(sk);
122}
123
124static void dccp_write_timer(struct timer_list *t)
125{
126 struct inet_connection_sock *icsk =
127 from_timer(icsk, t, icsk_retransmit_timer);
128 struct sock *sk = &icsk->icsk_inet.sk;
129 int event = 0;
130
131 bh_lock_sock(sk);
132 if (sock_owned_by_user(sk)) {
133 /* Try again later */
134 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
135 jiffies + (HZ / 20));
136 goto out;
137 }
138
139 if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending)
140 goto out;
141
142 if (time_after(icsk->icsk_timeout, jiffies)) {
143 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
144 icsk->icsk_timeout);
145 goto out;
146 }
147
148 event = icsk->icsk_pending;
149 icsk->icsk_pending = 0;
150
151 switch (event) {
152 case ICSK_TIME_RETRANS:
153 dccp_retransmit_timer(sk);
154 break;
155 }
156out:
157 bh_unlock_sock(sk);
158 sock_put(sk);
159}
160
161static void dccp_keepalive_timer(struct timer_list *t)
162{
163 struct sock *sk = from_timer(sk, t, sk_timer);
164
165 pr_err("dccp should not use a keepalive timer !\n");
166 sock_put(sk);
167}
168
169/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
170static void dccp_delack_timer(struct timer_list *t)
171{
172 struct inet_connection_sock *icsk =
173 from_timer(icsk, t, icsk_delack_timer);
174 struct sock *sk = &icsk->icsk_inet.sk;
175
176 bh_lock_sock(sk);
177 if (sock_owned_by_user(sk)) {
178 /* Try again later. */
179 icsk->icsk_ack.blocked = 1;
180 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
181 sk_reset_timer(sk, &icsk->icsk_delack_timer,
182 jiffies + TCP_DELACK_MIN);
183 goto out;
184 }
185
186 if (sk->sk_state == DCCP_CLOSED ||
187 !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
188 goto out;
189 if (time_after(icsk->icsk_ack.timeout, jiffies)) {
190 sk_reset_timer(sk, &icsk->icsk_delack_timer,
191 icsk->icsk_ack.timeout);
192 goto out;
193 }
194
195 icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
196
197 if (inet_csk_ack_scheduled(sk)) {
198 if (!inet_csk_in_pingpong_mode(sk)) {
199 /* Delayed ACK missed: inflate ATO. */
200 icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
201 icsk->icsk_rto);
202 } else {
203 /* Delayed ACK missed: leave pingpong mode and
204 * deflate ATO.
205 */
206 inet_csk_exit_pingpong_mode(sk);
207 icsk->icsk_ack.ato = TCP_ATO_MIN;
208 }
209 dccp_send_ack(sk);
210 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS);
211 }
212out:
213 bh_unlock_sock(sk);
214 sock_put(sk);
215}
216
217/**
218 * dccp_write_xmitlet - Workhorse for CCID packet dequeueing interface
219 * @data: Socket to act on
220 *
221 * See the comments above %ccid_dequeueing_decision for supported modes.
222 */
223static void dccp_write_xmitlet(unsigned long data)
224{
225 struct sock *sk = (struct sock *)data;
226
227 bh_lock_sock(sk);
228 if (sock_owned_by_user(sk))
229 sk_reset_timer(sk, &dccp_sk(sk)->dccps_xmit_timer, jiffies + 1);
230 else
231 dccp_write_xmit(sk);
232 bh_unlock_sock(sk);
233 sock_put(sk);
234}
235
236static void dccp_write_xmit_timer(struct timer_list *t)
237{
238 struct dccp_sock *dp = from_timer(dp, t, dccps_xmit_timer);
239 struct sock *sk = &dp->dccps_inet_connection.icsk_inet.sk;
240
241 dccp_write_xmitlet((unsigned long)sk);
242}
243
244void dccp_init_xmit_timers(struct sock *sk)
245{
246 struct dccp_sock *dp = dccp_sk(sk);
247
248 tasklet_init(&dp->dccps_xmitlet, dccp_write_xmitlet, (unsigned long)sk);
249 timer_setup(&dp->dccps_xmit_timer, dccp_write_xmit_timer, 0);
250 inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
251 &dccp_keepalive_timer);
252}
253
254static ktime_t dccp_timestamp_seed;
255/**
256 * dccp_timestamp - 10s of microseconds time source
257 * Returns the number of 10s of microseconds since loading DCCP. This is native
258 * DCCP time difference format (RFC 4340, sec. 13).
259 * Please note: This will wrap around about circa every 11.9 hours.
260 */
261u32 dccp_timestamp(void)
262{
263 u64 delta = (u64)ktime_us_delta(ktime_get_real(), dccp_timestamp_seed);
264
265 do_div(delta, 10);
266 return delta;
267}
268EXPORT_SYMBOL_GPL(dccp_timestamp);
269
270void __init dccp_timestamping_init(void)
271{
272 dccp_timestamp_seed = ktime_get_real();
273}