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.
6 * Definitions for the TCP module.
8 * Version: @(#)tcp.h 1.0.5 05/23/93
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
21 #define FASTRETRANS_DEBUG 1
23 #include <linux/list.h>
24 #include <linux/tcp.h>
25 #include <linux/bug.h>
26 #include <linux/slab.h>
27 #include <linux/cache.h>
28 #include <linux/percpu.h>
29 #include <linux/skbuff.h>
30 #include <linux/crypto.h>
31 #include <linux/cryptohash.h>
32 #include <linux/kref.h>
33 #include <linux/ktime.h>
35 #include <net/inet_connection_sock.h>
36 #include <net/inet_timewait_sock.h>
37 #include <net/inet_hashtables.h>
38 #include <net/checksum.h>
39 #include <net/request_sock.h>
43 #include <net/tcp_states.h>
44 #include <net/inet_ecn.h>
47 #include <linux/seq_file.h>
48 #include <linux/memcontrol.h>
50 extern struct inet_hashinfo tcp_hashinfo
;
52 extern struct percpu_counter tcp_orphan_count
;
53 void tcp_time_wait(struct sock
*sk
, int state
, int timeo
);
55 #define MAX_TCP_HEADER (128 + MAX_HEADER)
56 #define MAX_TCP_OPTION_SPACE 40
59 * Never offer a window over 32767 without using window scaling. Some
60 * poor stacks do signed 16bit maths!
62 #define MAX_TCP_WINDOW 32767U
64 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
65 #define TCP_MIN_MSS 88U
67 /* The least MTU to use for probing */
68 #define TCP_BASE_MSS 1024
70 /* probing interval, default to 10 minutes as per RFC4821 */
71 #define TCP_PROBE_INTERVAL 600
73 /* Specify interval when tcp mtu probing will stop */
74 #define TCP_PROBE_THRESHOLD 8
76 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
77 #define TCP_FASTRETRANS_THRESH 3
79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
80 #define TCP_MAX_QUICKACKS 16U
83 #define TCP_URG_VALID 0x0100
84 #define TCP_URG_NOTYET 0x0200
85 #define TCP_URG_READ 0x0400
87 #define TCP_RETR1 3 /*
88 * This is how many retries it does before it
89 * tries to figure out if the gateway is
90 * down. Minimal RFC value is 3; it corresponds
91 * to ~3sec-8min depending on RTO.
94 #define TCP_RETR2 15 /*
95 * This should take at least
96 * 90 minutes to time out.
97 * RFC1122 says that the limit is 100 sec.
98 * 15 is ~13-30min depending on RTO.
101 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
102 * when active opening a connection.
103 * RFC1122 says the minimum retry MUST
104 * be at least 180secs. Nevertheless
105 * this value is corresponding to
106 * 63secs of retransmission with the
107 * current initial RTO.
110 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
111 * when passive opening a connection.
112 * This is corresponding to 31secs of
113 * retransmission with the current
117 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
118 * state, about 60 seconds */
119 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
120 /* BSD style FIN_WAIT2 deadlock breaker.
121 * It used to be 3min, new value is 60sec,
122 * to combine FIN-WAIT-2 timeout with
126 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
128 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
129 #define TCP_ATO_MIN ((unsigned)(HZ/25))
131 #define TCP_DELACK_MIN 4U
132 #define TCP_ATO_MIN 4U
134 #define TCP_RTO_MAX ((unsigned)(120*HZ))
135 #define TCP_RTO_MIN ((unsigned)(HZ/5))
136 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
137 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
138 * used as a fallback RTO for the
139 * initial data transmission if no
140 * valid RTT sample has been acquired,
141 * most likely due to retrans in 3WHS.
144 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
145 * for local resources.
148 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
149 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
150 #define TCP_KEEPALIVE_INTVL (75*HZ)
152 #define MAX_TCP_KEEPIDLE 32767
153 #define MAX_TCP_KEEPINTVL 32767
154 #define MAX_TCP_KEEPCNT 127
155 #define MAX_TCP_SYNCNT 127
157 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
159 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
160 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
161 * after this time. It should be equal
162 * (or greater than) TCP_TIMEWAIT_LEN
163 * to provide reliability equal to one
164 * provided by timewait state.
166 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
167 * timestamps. It must be less than
168 * minimal timewait lifetime.
174 #define TCPOPT_NOP 1 /* Padding */
175 #define TCPOPT_EOL 0 /* End of options */
176 #define TCPOPT_MSS 2 /* Segment size negotiating */
177 #define TCPOPT_WINDOW 3 /* Window scaling */
178 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
179 #define TCPOPT_SACK 5 /* SACK Block */
180 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
181 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
182 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
183 #define TCPOPT_EXP 254 /* Experimental */
184 /* Magic number to be after the option value for sharing TCP
185 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
187 #define TCPOPT_FASTOPEN_MAGIC 0xF989
193 #define TCPOLEN_MSS 4
194 #define TCPOLEN_WINDOW 3
195 #define TCPOLEN_SACK_PERM 2
196 #define TCPOLEN_TIMESTAMP 10
197 #define TCPOLEN_MD5SIG 18
198 #define TCPOLEN_FASTOPEN_BASE 2
199 #define TCPOLEN_EXP_FASTOPEN_BASE 4
201 /* But this is what stacks really send out. */
202 #define TCPOLEN_TSTAMP_ALIGNED 12
203 #define TCPOLEN_WSCALE_ALIGNED 4
204 #define TCPOLEN_SACKPERM_ALIGNED 4
205 #define TCPOLEN_SACK_BASE 2
206 #define TCPOLEN_SACK_BASE_ALIGNED 4
207 #define TCPOLEN_SACK_PERBLOCK 8
208 #define TCPOLEN_MD5SIG_ALIGNED 20
209 #define TCPOLEN_MSS_ALIGNED 4
211 /* Flags in tp->nonagle */
212 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
213 #define TCP_NAGLE_CORK 2 /* Socket is corked */
214 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
216 /* TCP thin-stream limits */
217 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
219 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
220 #define TCP_INIT_CWND 10
222 /* Bit Flags for sysctl_tcp_fastopen */
223 #define TFO_CLIENT_ENABLE 1
224 #define TFO_SERVER_ENABLE 2
225 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
227 /* Accept SYN data w/o any cookie option */
228 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
230 /* Force enable TFO on all listeners, i.e., not requiring the
231 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
233 #define TFO_SERVER_WO_SOCKOPT1 0x400
234 #define TFO_SERVER_WO_SOCKOPT2 0x800
236 extern struct inet_timewait_death_row tcp_death_row
;
238 /* sysctl variables for tcp */
239 extern int sysctl_tcp_timestamps
;
240 extern int sysctl_tcp_window_scaling
;
241 extern int sysctl_tcp_sack
;
242 extern int sysctl_tcp_fin_timeout
;
243 extern int sysctl_tcp_keepalive_time
;
244 extern int sysctl_tcp_keepalive_probes
;
245 extern int sysctl_tcp_keepalive_intvl
;
246 extern int sysctl_tcp_syn_retries
;
247 extern int sysctl_tcp_synack_retries
;
248 extern int sysctl_tcp_retries1
;
249 extern int sysctl_tcp_retries2
;
250 extern int sysctl_tcp_orphan_retries
;
251 extern int sysctl_tcp_syncookies
;
252 extern int sysctl_tcp_fastopen
;
253 extern int sysctl_tcp_retrans_collapse
;
254 extern int sysctl_tcp_stdurg
;
255 extern int sysctl_tcp_rfc1337
;
256 extern int sysctl_tcp_abort_on_overflow
;
257 extern int sysctl_tcp_max_orphans
;
258 extern int sysctl_tcp_fack
;
259 extern int sysctl_tcp_reordering
;
260 extern int sysctl_tcp_max_reordering
;
261 extern int sysctl_tcp_dsack
;
262 extern long sysctl_tcp_mem
[3];
263 extern int sysctl_tcp_wmem
[3];
264 extern int sysctl_tcp_rmem
[3];
265 extern int sysctl_tcp_app_win
;
266 extern int sysctl_tcp_adv_win_scale
;
267 extern int sysctl_tcp_tw_reuse
;
268 extern int sysctl_tcp_frto
;
269 extern int sysctl_tcp_low_latency
;
270 extern int sysctl_tcp_nometrics_save
;
271 extern int sysctl_tcp_moderate_rcvbuf
;
272 extern int sysctl_tcp_tso_win_divisor
;
273 extern int sysctl_tcp_workaround_signed_windows
;
274 extern int sysctl_tcp_slow_start_after_idle
;
275 extern int sysctl_tcp_thin_linear_timeouts
;
276 extern int sysctl_tcp_thin_dupack
;
277 extern int sysctl_tcp_early_retrans
;
278 extern int sysctl_tcp_limit_output_bytes
;
279 extern int sysctl_tcp_challenge_ack_limit
;
280 extern unsigned int sysctl_tcp_notsent_lowat
;
281 extern int sysctl_tcp_min_tso_segs
;
282 extern int sysctl_tcp_autocorking
;
283 extern int sysctl_tcp_invalid_ratelimit
;
285 extern atomic_long_t tcp_memory_allocated
;
286 extern struct percpu_counter tcp_sockets_allocated
;
287 extern int tcp_memory_pressure
;
289 /* optimized version of sk_under_memory_pressure() for TCP sockets */
290 static inline bool tcp_under_memory_pressure(const struct sock
*sk
)
292 if (mem_cgroup_sockets_enabled
&& sk
->sk_cgrp
)
293 return !!sk
->sk_cgrp
->memory_pressure
;
295 return tcp_memory_pressure
;
298 * The next routines deal with comparing 32 bit unsigned ints
299 * and worry about wraparound (automatic with unsigned arithmetic).
302 static inline bool before(__u32 seq1
, __u32 seq2
)
304 return (__s32
)(seq1
-seq2
) < 0;
306 #define after(seq2, seq1) before(seq1, seq2)
308 /* is s2<=s1<=s3 ? */
309 static inline bool between(__u32 seq1
, __u32 seq2
, __u32 seq3
)
311 return seq3
- seq2
>= seq1
- seq2
;
314 static inline bool tcp_out_of_memory(struct sock
*sk
)
316 if (sk
->sk_wmem_queued
> SOCK_MIN_SNDBUF
&&
317 sk_memory_allocated(sk
) > sk_prot_mem_limits(sk
, 2))
322 void sk_forced_mem_schedule(struct sock
*sk
, int size
);
324 static inline bool tcp_too_many_orphans(struct sock
*sk
, int shift
)
326 struct percpu_counter
*ocp
= sk
->sk_prot
->orphan_count
;
327 int orphans
= percpu_counter_read_positive(ocp
);
329 if (orphans
<< shift
> sysctl_tcp_max_orphans
) {
330 orphans
= percpu_counter_sum_positive(ocp
);
331 if (orphans
<< shift
> sysctl_tcp_max_orphans
)
337 bool tcp_check_oom(struct sock
*sk
, int shift
);
340 extern struct proto tcp_prot
;
342 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
343 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
344 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
345 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
346 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
348 void tcp_tasklet_init(void);
350 void tcp_v4_err(struct sk_buff
*skb
, u32
);
352 void tcp_shutdown(struct sock
*sk
, int how
);
354 void tcp_v4_early_demux(struct sk_buff
*skb
);
355 int tcp_v4_rcv(struct sk_buff
*skb
);
357 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock
*tw
);
358 int tcp_sendmsg(struct sock
*sk
, struct msghdr
*msg
, size_t size
);
359 int tcp_sendpage(struct sock
*sk
, struct page
*page
, int offset
, size_t size
,
361 void tcp_release_cb(struct sock
*sk
);
362 void tcp_wfree(struct sk_buff
*skb
);
363 void tcp_write_timer_handler(struct sock
*sk
);
364 void tcp_delack_timer_handler(struct sock
*sk
);
365 int tcp_ioctl(struct sock
*sk
, int cmd
, unsigned long arg
);
366 int tcp_rcv_state_process(struct sock
*sk
, struct sk_buff
*skb
,
367 const struct tcphdr
*th
, unsigned int len
);
368 void tcp_rcv_established(struct sock
*sk
, struct sk_buff
*skb
,
369 const struct tcphdr
*th
, unsigned int len
);
370 void tcp_rcv_space_adjust(struct sock
*sk
);
371 int tcp_twsk_unique(struct sock
*sk
, struct sock
*sktw
, void *twp
);
372 void tcp_twsk_destructor(struct sock
*sk
);
373 ssize_t
tcp_splice_read(struct socket
*sk
, loff_t
*ppos
,
374 struct pipe_inode_info
*pipe
, size_t len
,
377 static inline void tcp_dec_quickack_mode(struct sock
*sk
,
378 const unsigned int pkts
)
380 struct inet_connection_sock
*icsk
= inet_csk(sk
);
382 if (icsk
->icsk_ack
.quick
) {
383 if (pkts
>= icsk
->icsk_ack
.quick
) {
384 icsk
->icsk_ack
.quick
= 0;
385 /* Leaving quickack mode we deflate ATO. */
386 icsk
->icsk_ack
.ato
= TCP_ATO_MIN
;
388 icsk
->icsk_ack
.quick
-= pkts
;
393 #define TCP_ECN_QUEUE_CWR 2
394 #define TCP_ECN_DEMAND_CWR 4
395 #define TCP_ECN_SEEN 8
405 enum tcp_tw_status
tcp_timewait_state_process(struct inet_timewait_sock
*tw
,
407 const struct tcphdr
*th
);
408 struct sock
*tcp_check_req(struct sock
*sk
, struct sk_buff
*skb
,
409 struct request_sock
*req
, bool fastopen
);
410 int tcp_child_process(struct sock
*parent
, struct sock
*child
,
411 struct sk_buff
*skb
);
412 void tcp_enter_loss(struct sock
*sk
);
413 void tcp_clear_retrans(struct tcp_sock
*tp
);
414 void tcp_update_metrics(struct sock
*sk
);
415 void tcp_init_metrics(struct sock
*sk
);
416 void tcp_metrics_init(void);
417 bool tcp_peer_is_proven(struct request_sock
*req
, struct dst_entry
*dst
,
418 bool paws_check
, bool timestamps
);
419 bool tcp_remember_stamp(struct sock
*sk
);
420 bool tcp_tw_remember_stamp(struct inet_timewait_sock
*tw
);
421 void tcp_fetch_timewait_stamp(struct sock
*sk
, struct dst_entry
*dst
);
422 void tcp_disable_fack(struct tcp_sock
*tp
);
423 void tcp_close(struct sock
*sk
, long timeout
);
424 void tcp_init_sock(struct sock
*sk
);
425 unsigned int tcp_poll(struct file
*file
, struct socket
*sock
,
426 struct poll_table_struct
*wait
);
427 int tcp_getsockopt(struct sock
*sk
, int level
, int optname
,
428 char __user
*optval
, int __user
*optlen
);
429 int tcp_setsockopt(struct sock
*sk
, int level
, int optname
,
430 char __user
*optval
, unsigned int optlen
);
431 int compat_tcp_getsockopt(struct sock
*sk
, int level
, int optname
,
432 char __user
*optval
, int __user
*optlen
);
433 int compat_tcp_setsockopt(struct sock
*sk
, int level
, int optname
,
434 char __user
*optval
, unsigned int optlen
);
435 void tcp_set_keepalive(struct sock
*sk
, int val
);
436 void tcp_syn_ack_timeout(const struct request_sock
*req
);
437 int tcp_recvmsg(struct sock
*sk
, struct msghdr
*msg
, size_t len
, int nonblock
,
438 int flags
, int *addr_len
);
439 void tcp_parse_options(const struct sk_buff
*skb
,
440 struct tcp_options_received
*opt_rx
,
441 int estab
, struct tcp_fastopen_cookie
*foc
);
442 const u8
*tcp_parse_md5sig_option(const struct tcphdr
*th
);
445 * TCP v4 functions exported for the inet6 API
448 void tcp_v4_send_check(struct sock
*sk
, struct sk_buff
*skb
);
449 void tcp_v4_mtu_reduced(struct sock
*sk
);
450 void tcp_req_err(struct sock
*sk
, u32 seq
);
451 int tcp_v4_conn_request(struct sock
*sk
, struct sk_buff
*skb
);
452 struct sock
*tcp_create_openreq_child(struct sock
*sk
,
453 struct request_sock
*req
,
454 struct sk_buff
*skb
);
455 void tcp_ca_openreq_child(struct sock
*sk
, const struct dst_entry
*dst
);
456 struct sock
*tcp_v4_syn_recv_sock(struct sock
*sk
, struct sk_buff
*skb
,
457 struct request_sock
*req
,
458 struct dst_entry
*dst
);
459 int tcp_v4_do_rcv(struct sock
*sk
, struct sk_buff
*skb
);
460 int tcp_v4_connect(struct sock
*sk
, struct sockaddr
*uaddr
, int addr_len
);
461 int tcp_connect(struct sock
*sk
);
462 struct sk_buff
*tcp_make_synack(struct sock
*sk
, struct dst_entry
*dst
,
463 struct request_sock
*req
,
464 struct tcp_fastopen_cookie
*foc
);
465 int tcp_disconnect(struct sock
*sk
, int flags
);
467 void tcp_finish_connect(struct sock
*sk
, struct sk_buff
*skb
);
468 int tcp_send_rcvq(struct sock
*sk
, struct msghdr
*msg
, size_t size
);
469 void inet_sk_rx_dst_set(struct sock
*sk
, const struct sk_buff
*skb
);
471 /* From syncookies.c */
472 int __cookie_v4_check(const struct iphdr
*iph
, const struct tcphdr
*th
,
474 struct sock
*cookie_v4_check(struct sock
*sk
, struct sk_buff
*skb
);
475 #ifdef CONFIG_SYN_COOKIES
477 /* Syncookies use a monotonic timer which increments every 60 seconds.
478 * This counter is used both as a hash input and partially encoded into
479 * the cookie value. A cookie is only validated further if the delta
480 * between the current counter value and the encoded one is less than this,
481 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
482 * the counter advances immediately after a cookie is generated).
484 #define MAX_SYNCOOKIE_AGE 2
485 #define TCP_SYNCOOKIE_PERIOD (60 * HZ)
486 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
488 /* syncookies: remember time of last synqueue overflow
489 * But do not dirty this field too often (once per second is enough)
491 static inline void tcp_synq_overflow(struct sock
*sk
)
493 unsigned long last_overflow
= tcp_sk(sk
)->rx_opt
.ts_recent_stamp
;
494 unsigned long now
= jiffies
;
496 if (time_after(now
, last_overflow
+ HZ
))
497 tcp_sk(sk
)->rx_opt
.ts_recent_stamp
= now
;
500 /* syncookies: no recent synqueue overflow on this listening socket? */
501 static inline bool tcp_synq_no_recent_overflow(const struct sock
*sk
)
503 unsigned long last_overflow
= tcp_sk(sk
)->rx_opt
.ts_recent_stamp
;
505 return time_after(jiffies
, last_overflow
+ TCP_SYNCOOKIE_VALID
);
508 static inline u32
tcp_cookie_time(void)
510 u64 val
= get_jiffies_64();
512 do_div(val
, TCP_SYNCOOKIE_PERIOD
);
516 u32
__cookie_v4_init_sequence(const struct iphdr
*iph
, const struct tcphdr
*th
,
518 __u32
cookie_v4_init_sequence(struct sock
*sk
, const struct sk_buff
*skb
,
520 __u32
cookie_init_timestamp(struct request_sock
*req
);
521 bool cookie_timestamp_decode(struct tcp_options_received
*opt
);
522 bool cookie_ecn_ok(const struct tcp_options_received
*opt
,
523 const struct net
*net
, const struct dst_entry
*dst
);
525 /* From net/ipv6/syncookies.c */
526 int __cookie_v6_check(const struct ipv6hdr
*iph
, const struct tcphdr
*th
,
528 struct sock
*cookie_v6_check(struct sock
*sk
, struct sk_buff
*skb
);
530 u32
__cookie_v6_init_sequence(const struct ipv6hdr
*iph
,
531 const struct tcphdr
*th
, u16
*mssp
);
532 __u32
cookie_v6_init_sequence(struct sock
*sk
, const struct sk_buff
*skb
,
537 void __tcp_push_pending_frames(struct sock
*sk
, unsigned int cur_mss
,
539 bool tcp_may_send_now(struct sock
*sk
);
540 int __tcp_retransmit_skb(struct sock
*, struct sk_buff
*);
541 int tcp_retransmit_skb(struct sock
*, struct sk_buff
*);
542 void tcp_retransmit_timer(struct sock
*sk
);
543 void tcp_xmit_retransmit_queue(struct sock
*);
544 void tcp_simple_retransmit(struct sock
*);
545 int tcp_trim_head(struct sock
*, struct sk_buff
*, u32
);
546 int tcp_fragment(struct sock
*, struct sk_buff
*, u32
, unsigned int, gfp_t
);
548 void tcp_send_probe0(struct sock
*);
549 void tcp_send_partial(struct sock
*);
550 int tcp_write_wakeup(struct sock
*, int mib
);
551 void tcp_send_fin(struct sock
*sk
);
552 void tcp_send_active_reset(struct sock
*sk
, gfp_t priority
);
553 int tcp_send_synack(struct sock
*);
554 void tcp_push_one(struct sock
*, unsigned int mss_now
);
555 void tcp_send_ack(struct sock
*sk
);
556 void tcp_send_delayed_ack(struct sock
*sk
);
557 void tcp_send_loss_probe(struct sock
*sk
);
558 bool tcp_schedule_loss_probe(struct sock
*sk
);
561 void tcp_resume_early_retransmit(struct sock
*sk
);
562 void tcp_rearm_rto(struct sock
*sk
);
563 void tcp_reset(struct sock
*sk
);
566 void tcp_init_xmit_timers(struct sock
*);
567 static inline void tcp_clear_xmit_timers(struct sock
*sk
)
569 inet_csk_clear_xmit_timers(sk
);
572 unsigned int tcp_sync_mss(struct sock
*sk
, u32 pmtu
);
573 unsigned int tcp_current_mss(struct sock
*sk
);
575 /* Bound MSS / TSO packet size with the half of the window */
576 static inline int tcp_bound_to_half_wnd(struct tcp_sock
*tp
, int pktsize
)
580 /* When peer uses tiny windows, there is no use in packetizing
581 * to sub-MSS pieces for the sake of SWS or making sure there
582 * are enough packets in the pipe for fast recovery.
584 * On the other hand, for extremely large MSS devices, handling
585 * smaller than MSS windows in this way does make sense.
587 if (tp
->max_window
>= 512)
588 cutoff
= (tp
->max_window
>> 1);
590 cutoff
= tp
->max_window
;
592 if (cutoff
&& pktsize
> cutoff
)
593 return max_t(int, cutoff
, 68U - tp
->tcp_header_len
);
599 void tcp_get_info(struct sock
*, struct tcp_info
*);
601 /* Read 'sendfile()'-style from a TCP socket */
602 typedef int (*sk_read_actor_t
)(read_descriptor_t
*, struct sk_buff
*,
603 unsigned int, size_t);
604 int tcp_read_sock(struct sock
*sk
, read_descriptor_t
*desc
,
605 sk_read_actor_t recv_actor
);
607 void tcp_initialize_rcv_mss(struct sock
*sk
);
609 int tcp_mtu_to_mss(struct sock
*sk
, int pmtu
);
610 int tcp_mss_to_mtu(struct sock
*sk
, int mss
);
611 void tcp_mtup_init(struct sock
*sk
);
612 void tcp_init_buffer_space(struct sock
*sk
);
614 static inline void tcp_bound_rto(const struct sock
*sk
)
616 if (inet_csk(sk
)->icsk_rto
> TCP_RTO_MAX
)
617 inet_csk(sk
)->icsk_rto
= TCP_RTO_MAX
;
620 static inline u32
__tcp_set_rto(const struct tcp_sock
*tp
)
622 return usecs_to_jiffies((tp
->srtt_us
>> 3) + tp
->rttvar_us
);
625 static inline void __tcp_fast_path_on(struct tcp_sock
*tp
, u32 snd_wnd
)
627 tp
->pred_flags
= htonl((tp
->tcp_header_len
<< 26) |
628 ntohl(TCP_FLAG_ACK
) |
632 static inline void tcp_fast_path_on(struct tcp_sock
*tp
)
634 __tcp_fast_path_on(tp
, tp
->snd_wnd
>> tp
->rx_opt
.snd_wscale
);
637 static inline void tcp_fast_path_check(struct sock
*sk
)
639 struct tcp_sock
*tp
= tcp_sk(sk
);
641 if (skb_queue_empty(&tp
->out_of_order_queue
) &&
643 atomic_read(&sk
->sk_rmem_alloc
) < sk
->sk_rcvbuf
&&
645 tcp_fast_path_on(tp
);
648 /* Compute the actual rto_min value */
649 static inline u32
tcp_rto_min(struct sock
*sk
)
651 const struct dst_entry
*dst
= __sk_dst_get(sk
);
652 u32 rto_min
= TCP_RTO_MIN
;
654 if (dst
&& dst_metric_locked(dst
, RTAX_RTO_MIN
))
655 rto_min
= dst_metric_rtt(dst
, RTAX_RTO_MIN
);
659 static inline u32
tcp_rto_min_us(struct sock
*sk
)
661 return jiffies_to_usecs(tcp_rto_min(sk
));
664 static inline bool tcp_ca_dst_locked(const struct dst_entry
*dst
)
666 return dst_metric_locked(dst
, RTAX_CC_ALGO
);
669 /* Compute the actual receive window we are currently advertising.
670 * Rcv_nxt can be after the window if our peer push more data
671 * than the offered window.
673 static inline u32
tcp_receive_window(const struct tcp_sock
*tp
)
675 s32 win
= tp
->rcv_wup
+ tp
->rcv_wnd
- tp
->rcv_nxt
;
682 /* Choose a new window, without checks for shrinking, and without
683 * scaling applied to the result. The caller does these things
684 * if necessary. This is a "raw" window selection.
686 u32
__tcp_select_window(struct sock
*sk
);
688 void tcp_send_window_probe(struct sock
*sk
);
690 /* TCP timestamps are only 32-bits, this causes a slight
691 * complication on 64-bit systems since we store a snapshot
692 * of jiffies in the buffer control blocks below. We decided
693 * to use only the low 32-bits of jiffies and hide the ugly
694 * casts with the following macro.
696 #define tcp_time_stamp ((__u32)(jiffies))
698 static inline u32
tcp_skb_timestamp(const struct sk_buff
*skb
)
700 return skb
->skb_mstamp
.stamp_jiffies
;
704 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
706 #define TCPHDR_FIN 0x01
707 #define TCPHDR_SYN 0x02
708 #define TCPHDR_RST 0x04
709 #define TCPHDR_PSH 0x08
710 #define TCPHDR_ACK 0x10
711 #define TCPHDR_URG 0x20
712 #define TCPHDR_ECE 0x40
713 #define TCPHDR_CWR 0x80
715 /* This is what the send packet queuing engine uses to pass
716 * TCP per-packet control information to the transmission code.
717 * We also store the host-order sequence numbers in here too.
718 * This is 44 bytes if IPV6 is enabled.
719 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
722 __u32 seq
; /* Starting sequence number */
723 __u32 end_seq
; /* SEQ + FIN + SYN + datalen */
725 /* Note : tcp_tw_isn is used in input path only
726 * (isn chosen by tcp_timewait_state_process())
728 * tcp_gso_segs is used in write queue only,
729 * cf tcp_skb_pcount()
734 __u8 tcp_flags
; /* TCP header flags. (tcp[13]) */
736 __u8 sacked
; /* State flags for SACK/FACK. */
737 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
738 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
739 #define TCPCB_LOST 0x04 /* SKB is lost */
740 #define TCPCB_TAGBITS 0x07 /* All tag bits */
741 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
742 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
743 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
746 __u8 ip_dsfield
; /* IPv4 tos or IPv6 dsfield */
748 __u32 ack_seq
; /* Sequence number ACK'd */
750 struct inet_skb_parm h4
;
751 #if IS_ENABLED(CONFIG_IPV6)
752 struct inet6_skb_parm h6
;
754 } header
; /* For incoming frames */
757 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
760 #if IS_ENABLED(CONFIG_IPV6)
761 /* This is the variant of inet6_iif() that must be used by TCP,
762 * as TCP moves IP6CB into a different location in skb->cb[]
764 static inline int tcp_v6_iif(const struct sk_buff
*skb
)
766 return TCP_SKB_CB(skb
)->header
.h6
.iif
;
770 /* Due to TSO, an SKB can be composed of multiple actual
771 * packets. To keep these tracked properly, we use this.
773 static inline int tcp_skb_pcount(const struct sk_buff
*skb
)
775 return TCP_SKB_CB(skb
)->tcp_gso_segs
;
778 static inline void tcp_skb_pcount_set(struct sk_buff
*skb
, int segs
)
780 TCP_SKB_CB(skb
)->tcp_gso_segs
= segs
;
783 static inline void tcp_skb_pcount_add(struct sk_buff
*skb
, int segs
)
785 TCP_SKB_CB(skb
)->tcp_gso_segs
+= segs
;
788 /* This is valid iff tcp_skb_pcount() > 1. */
789 static inline int tcp_skb_mss(const struct sk_buff
*skb
)
791 return skb_shinfo(skb
)->gso_size
;
794 /* Events passed to congestion control interface */
796 CA_EVENT_TX_START
, /* first transmit when no packets in flight */
797 CA_EVENT_CWND_RESTART
, /* congestion window restart */
798 CA_EVENT_COMPLETE_CWR
, /* end of congestion recovery */
799 CA_EVENT_LOSS
, /* loss timeout */
800 CA_EVENT_ECN_NO_CE
, /* ECT set, but not CE marked */
801 CA_EVENT_ECN_IS_CE
, /* received CE marked IP packet */
802 CA_EVENT_DELAYED_ACK
, /* Delayed ack is sent */
803 CA_EVENT_NON_DELAYED_ACK
,
806 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
807 enum tcp_ca_ack_event_flags
{
808 CA_ACK_SLOWPATH
= (1 << 0), /* In slow path processing */
809 CA_ACK_WIN_UPDATE
= (1 << 1), /* ACK updated window */
810 CA_ACK_ECE
= (1 << 2), /* ECE bit is set on ack */
814 * Interface for adding new TCP congestion control handlers
816 #define TCP_CA_NAME_MAX 16
817 #define TCP_CA_MAX 128
818 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
820 #define TCP_CA_UNSPEC 0
822 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
823 #define TCP_CONG_NON_RESTRICTED 0x1
824 /* Requires ECN/ECT set on all packets */
825 #define TCP_CONG_NEEDS_ECN 0x2
829 struct tcp_congestion_ops
{
830 struct list_head list
;
834 /* initialize private data (optional) */
835 void (*init
)(struct sock
*sk
);
836 /* cleanup private data (optional) */
837 void (*release
)(struct sock
*sk
);
839 /* return slow start threshold (required) */
840 u32 (*ssthresh
)(struct sock
*sk
);
841 /* do new cwnd calculation (required) */
842 void (*cong_avoid
)(struct sock
*sk
, u32 ack
, u32 acked
);
843 /* call before changing ca_state (optional) */
844 void (*set_state
)(struct sock
*sk
, u8 new_state
);
845 /* call when cwnd event occurs (optional) */
846 void (*cwnd_event
)(struct sock
*sk
, enum tcp_ca_event ev
);
847 /* call when ack arrives (optional) */
848 void (*in_ack_event
)(struct sock
*sk
, u32 flags
);
849 /* new value of cwnd after loss (optional) */
850 u32 (*undo_cwnd
)(struct sock
*sk
);
851 /* hook for packet ack accounting (optional) */
852 void (*pkts_acked
)(struct sock
*sk
, u32 num_acked
, s32 rtt_us
);
853 /* get info for inet_diag (optional) */
854 size_t (*get_info
)(struct sock
*sk
, u32 ext
, int *attr
,
855 union tcp_cc_info
*info
);
857 char name
[TCP_CA_NAME_MAX
];
858 struct module
*owner
;
861 int tcp_register_congestion_control(struct tcp_congestion_ops
*type
);
862 void tcp_unregister_congestion_control(struct tcp_congestion_ops
*type
);
864 void tcp_assign_congestion_control(struct sock
*sk
);
865 void tcp_init_congestion_control(struct sock
*sk
);
866 void tcp_cleanup_congestion_control(struct sock
*sk
);
867 int tcp_set_default_congestion_control(const char *name
);
868 void tcp_get_default_congestion_control(char *name
);
869 void tcp_get_available_congestion_control(char *buf
, size_t len
);
870 void tcp_get_allowed_congestion_control(char *buf
, size_t len
);
871 int tcp_set_allowed_congestion_control(char *allowed
);
872 int tcp_set_congestion_control(struct sock
*sk
, const char *name
);
873 u32
tcp_slow_start(struct tcp_sock
*tp
, u32 acked
);
874 void tcp_cong_avoid_ai(struct tcp_sock
*tp
, u32 w
, u32 acked
);
876 u32
tcp_reno_ssthresh(struct sock
*sk
);
877 void tcp_reno_cong_avoid(struct sock
*sk
, u32 ack
, u32 acked
);
878 extern struct tcp_congestion_ops tcp_reno
;
880 struct tcp_congestion_ops
*tcp_ca_find_key(u32 key
);
881 u32
tcp_ca_get_key_by_name(const char *name
);
883 char *tcp_ca_get_name_by_key(u32 key
, char *buffer
);
885 static inline char *tcp_ca_get_name_by_key(u32 key
, char *buffer
)
891 static inline bool tcp_ca_needs_ecn(const struct sock
*sk
)
893 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
895 return icsk
->icsk_ca_ops
->flags
& TCP_CONG_NEEDS_ECN
;
898 static inline void tcp_set_ca_state(struct sock
*sk
, const u8 ca_state
)
900 struct inet_connection_sock
*icsk
= inet_csk(sk
);
902 if (icsk
->icsk_ca_ops
->set_state
)
903 icsk
->icsk_ca_ops
->set_state(sk
, ca_state
);
904 icsk
->icsk_ca_state
= ca_state
;
907 static inline void tcp_ca_event(struct sock
*sk
, const enum tcp_ca_event event
)
909 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
911 if (icsk
->icsk_ca_ops
->cwnd_event
)
912 icsk
->icsk_ca_ops
->cwnd_event(sk
, event
);
915 /* These functions determine how the current flow behaves in respect of SACK
916 * handling. SACK is negotiated with the peer, and therefore it can vary
917 * between different flows.
919 * tcp_is_sack - SACK enabled
920 * tcp_is_reno - No SACK
921 * tcp_is_fack - FACK enabled, implies SACK enabled
923 static inline int tcp_is_sack(const struct tcp_sock
*tp
)
925 return tp
->rx_opt
.sack_ok
;
928 static inline bool tcp_is_reno(const struct tcp_sock
*tp
)
930 return !tcp_is_sack(tp
);
933 static inline bool tcp_is_fack(const struct tcp_sock
*tp
)
935 return tp
->rx_opt
.sack_ok
& TCP_FACK_ENABLED
;
938 static inline void tcp_enable_fack(struct tcp_sock
*tp
)
940 tp
->rx_opt
.sack_ok
|= TCP_FACK_ENABLED
;
943 /* TCP early-retransmit (ER) is similar to but more conservative than
944 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
946 static inline void tcp_enable_early_retrans(struct tcp_sock
*tp
)
948 tp
->do_early_retrans
= sysctl_tcp_early_retrans
&&
949 sysctl_tcp_early_retrans
< 4 && !sysctl_tcp_thin_dupack
&&
950 sysctl_tcp_reordering
== 3;
953 static inline void tcp_disable_early_retrans(struct tcp_sock
*tp
)
955 tp
->do_early_retrans
= 0;
958 static inline unsigned int tcp_left_out(const struct tcp_sock
*tp
)
960 return tp
->sacked_out
+ tp
->lost_out
;
963 /* This determines how many packets are "in the network" to the best
964 * of our knowledge. In many cases it is conservative, but where
965 * detailed information is available from the receiver (via SACK
966 * blocks etc.) we can make more aggressive calculations.
968 * Use this for decisions involving congestion control, use just
969 * tp->packets_out to determine if the send queue is empty or not.
971 * Read this equation as:
973 * "Packets sent once on transmission queue" MINUS
974 * "Packets left network, but not honestly ACKed yet" PLUS
975 * "Packets fast retransmitted"
977 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock
*tp
)
979 return tp
->packets_out
- tcp_left_out(tp
) + tp
->retrans_out
;
982 #define TCP_INFINITE_SSTHRESH 0x7fffffff
984 static inline bool tcp_in_initial_slowstart(const struct tcp_sock
*tp
)
986 return tp
->snd_ssthresh
>= TCP_INFINITE_SSTHRESH
;
989 static inline bool tcp_in_cwnd_reduction(const struct sock
*sk
)
991 return (TCPF_CA_CWR
| TCPF_CA_Recovery
) &
992 (1 << inet_csk(sk
)->icsk_ca_state
);
995 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
996 * The exception is cwnd reduction phase, when cwnd is decreasing towards
999 static inline __u32
tcp_current_ssthresh(const struct sock
*sk
)
1001 const struct tcp_sock
*tp
= tcp_sk(sk
);
1003 if (tcp_in_cwnd_reduction(sk
))
1004 return tp
->snd_ssthresh
;
1006 return max(tp
->snd_ssthresh
,
1007 ((tp
->snd_cwnd
>> 1) +
1008 (tp
->snd_cwnd
>> 2)));
1011 /* Use define here intentionally to get WARN_ON location shown at the caller */
1012 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1014 void tcp_enter_cwr(struct sock
*sk
);
1015 __u32
tcp_init_cwnd(const struct tcp_sock
*tp
, const struct dst_entry
*dst
);
1017 /* The maximum number of MSS of available cwnd for which TSO defers
1018 * sending if not using sysctl_tcp_tso_win_divisor.
1020 static inline __u32
tcp_max_tso_deferred_mss(const struct tcp_sock
*tp
)
1025 /* Slow start with delack produces 3 packets of burst, so that
1026 * it is safe "de facto". This will be the default - same as
1027 * the default reordering threshold - but if reordering increases,
1028 * we must be able to allow cwnd to burst at least this much in order
1029 * to not pull it back when holes are filled.
1031 static __inline__ __u32
tcp_max_burst(const struct tcp_sock
*tp
)
1033 return tp
->reordering
;
1036 /* Returns end sequence number of the receiver's advertised window */
1037 static inline u32
tcp_wnd_end(const struct tcp_sock
*tp
)
1039 return tp
->snd_una
+ tp
->snd_wnd
;
1042 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1043 * flexible approach. The RFC suggests cwnd should not be raised unless
1044 * it was fully used previously. And that's exactly what we do in
1045 * congestion avoidance mode. But in slow start we allow cwnd to grow
1046 * as long as the application has used half the cwnd.
1048 * cwnd is 10 (IW10), but application sends 9 frames.
1049 * We allow cwnd to reach 18 when all frames are ACKed.
1050 * This check is safe because it's as aggressive as slow start which already
1051 * risks 100% overshoot. The advantage is that we discourage application to
1052 * either send more filler packets or data to artificially blow up the cwnd
1053 * usage, and allow application-limited process to probe bw more aggressively.
1055 static inline bool tcp_is_cwnd_limited(const struct sock
*sk
)
1057 const struct tcp_sock
*tp
= tcp_sk(sk
);
1059 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1060 if (tp
->snd_cwnd
<= tp
->snd_ssthresh
)
1061 return tp
->snd_cwnd
< 2 * tp
->max_packets_out
;
1063 return tp
->is_cwnd_limited
;
1066 /* Something is really bad, we could not queue an additional packet,
1067 * because qdisc is full or receiver sent a 0 window.
1068 * We do not want to add fuel to the fire, or abort too early,
1069 * so make sure the timer we arm now is at least 200ms in the future,
1070 * regardless of current icsk_rto value (as it could be ~2ms)
1072 static inline unsigned long tcp_probe0_base(const struct sock
*sk
)
1074 return max_t(unsigned long, inet_csk(sk
)->icsk_rto
, TCP_RTO_MIN
);
1077 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1078 static inline unsigned long tcp_probe0_when(const struct sock
*sk
,
1079 unsigned long max_when
)
1081 u64 when
= (u64
)tcp_probe0_base(sk
) << inet_csk(sk
)->icsk_backoff
;
1083 return (unsigned long)min_t(u64
, when
, max_when
);
1086 static inline void tcp_check_probe_timer(struct sock
*sk
)
1088 if (!tcp_sk(sk
)->packets_out
&& !inet_csk(sk
)->icsk_pending
)
1089 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_PROBE0
,
1090 tcp_probe0_base(sk
), TCP_RTO_MAX
);
1093 static inline void tcp_init_wl(struct tcp_sock
*tp
, u32 seq
)
1098 static inline void tcp_update_wl(struct tcp_sock
*tp
, u32 seq
)
1104 * Calculate(/check) TCP checksum
1106 static inline __sum16
tcp_v4_check(int len
, __be32 saddr
,
1107 __be32 daddr
, __wsum base
)
1109 return csum_tcpudp_magic(saddr
,daddr
,len
,IPPROTO_TCP
,base
);
1112 static inline __sum16
__tcp_checksum_complete(struct sk_buff
*skb
)
1114 return __skb_checksum_complete(skb
);
1117 static inline bool tcp_checksum_complete(struct sk_buff
*skb
)
1119 return !skb_csum_unnecessary(skb
) &&
1120 __tcp_checksum_complete(skb
);
1123 /* Prequeue for VJ style copy to user, combined with checksumming. */
1125 static inline void tcp_prequeue_init(struct tcp_sock
*tp
)
1127 tp
->ucopy
.task
= NULL
;
1129 tp
->ucopy
.memory
= 0;
1130 skb_queue_head_init(&tp
->ucopy
.prequeue
);
1133 bool tcp_prequeue(struct sock
*sk
, struct sk_buff
*skb
);
1138 static const char *statename
[]={
1139 "Unused","Established","Syn Sent","Syn Recv",
1140 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1141 "Close Wait","Last ACK","Listen","Closing"
1144 void tcp_set_state(struct sock
*sk
, int state
);
1146 void tcp_done(struct sock
*sk
);
1148 static inline void tcp_sack_reset(struct tcp_options_received
*rx_opt
)
1151 rx_opt
->num_sacks
= 0;
1154 u32
tcp_default_init_rwnd(u32 mss
);
1156 /* Determine a window scaling and initial window to offer. */
1157 void tcp_select_initial_window(int __space
, __u32 mss
, __u32
*rcv_wnd
,
1158 __u32
*window_clamp
, int wscale_ok
,
1159 __u8
*rcv_wscale
, __u32 init_rcv_wnd
);
1161 static inline int tcp_win_from_space(int space
)
1163 return sysctl_tcp_adv_win_scale
<=0 ?
1164 (space
>>(-sysctl_tcp_adv_win_scale
)) :
1165 space
- (space
>>sysctl_tcp_adv_win_scale
);
1168 /* Note: caller must be prepared to deal with negative returns */
1169 static inline int tcp_space(const struct sock
*sk
)
1171 return tcp_win_from_space(sk
->sk_rcvbuf
-
1172 atomic_read(&sk
->sk_rmem_alloc
));
1175 static inline int tcp_full_space(const struct sock
*sk
)
1177 return tcp_win_from_space(sk
->sk_rcvbuf
);
1180 extern void tcp_openreq_init_rwin(struct request_sock
*req
,
1181 struct sock
*sk
, struct dst_entry
*dst
);
1183 void tcp_enter_memory_pressure(struct sock
*sk
);
1185 static inline int keepalive_intvl_when(const struct tcp_sock
*tp
)
1187 return tp
->keepalive_intvl
? : sysctl_tcp_keepalive_intvl
;
1190 static inline int keepalive_time_when(const struct tcp_sock
*tp
)
1192 return tp
->keepalive_time
? : sysctl_tcp_keepalive_time
;
1195 static inline int keepalive_probes(const struct tcp_sock
*tp
)
1197 return tp
->keepalive_probes
? : sysctl_tcp_keepalive_probes
;
1200 static inline u32
keepalive_time_elapsed(const struct tcp_sock
*tp
)
1202 const struct inet_connection_sock
*icsk
= &tp
->inet_conn
;
1204 return min_t(u32
, tcp_time_stamp
- icsk
->icsk_ack
.lrcvtime
,
1205 tcp_time_stamp
- tp
->rcv_tstamp
);
1208 static inline int tcp_fin_time(const struct sock
*sk
)
1210 int fin_timeout
= tcp_sk(sk
)->linger2
? : sysctl_tcp_fin_timeout
;
1211 const int rto
= inet_csk(sk
)->icsk_rto
;
1213 if (fin_timeout
< (rto
<< 2) - (rto
>> 1))
1214 fin_timeout
= (rto
<< 2) - (rto
>> 1);
1219 static inline bool tcp_paws_check(const struct tcp_options_received
*rx_opt
,
1222 if ((s32
)(rx_opt
->ts_recent
- rx_opt
->rcv_tsval
) <= paws_win
)
1224 if (unlikely(get_seconds() >= rx_opt
->ts_recent_stamp
+ TCP_PAWS_24DAYS
))
1227 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1228 * then following tcp messages have valid values. Ignore 0 value,
1229 * or else 'negative' tsval might forbid us to accept their packets.
1231 if (!rx_opt
->ts_recent
)
1236 static inline bool tcp_paws_reject(const struct tcp_options_received
*rx_opt
,
1239 if (tcp_paws_check(rx_opt
, 0))
1242 /* RST segments are not recommended to carry timestamp,
1243 and, if they do, it is recommended to ignore PAWS because
1244 "their cleanup function should take precedence over timestamps."
1245 Certainly, it is mistake. It is necessary to understand the reasons
1246 of this constraint to relax it: if peer reboots, clock may go
1247 out-of-sync and half-open connections will not be reset.
1248 Actually, the problem would be not existing if all
1249 the implementations followed draft about maintaining clock
1250 via reboots. Linux-2.2 DOES NOT!
1252 However, we can relax time bounds for RST segments to MSL.
1254 if (rst
&& get_seconds() >= rx_opt
->ts_recent_stamp
+ TCP_PAWS_MSL
)
1259 bool tcp_oow_rate_limited(struct net
*net
, const struct sk_buff
*skb
,
1260 int mib_idx
, u32
*last_oow_ack_time
);
1262 static inline void tcp_mib_init(struct net
*net
)
1265 TCP_ADD_STATS_USER(net
, TCP_MIB_RTOALGORITHM
, 1);
1266 TCP_ADD_STATS_USER(net
, TCP_MIB_RTOMIN
, TCP_RTO_MIN
*1000/HZ
);
1267 TCP_ADD_STATS_USER(net
, TCP_MIB_RTOMAX
, TCP_RTO_MAX
*1000/HZ
);
1268 TCP_ADD_STATS_USER(net
, TCP_MIB_MAXCONN
, -1);
1272 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock
*tp
)
1274 tp
->lost_skb_hint
= NULL
;
1277 static inline void tcp_clear_all_retrans_hints(struct tcp_sock
*tp
)
1279 tcp_clear_retrans_hints_partial(tp
);
1280 tp
->retransmit_skb_hint
= NULL
;
1286 union tcp_md5_addr
{
1288 #if IS_ENABLED(CONFIG_IPV6)
1293 /* - key database */
1294 struct tcp_md5sig_key
{
1295 struct hlist_node node
;
1297 u8 family
; /* AF_INET or AF_INET6 */
1298 union tcp_md5_addr addr
;
1299 u8 key
[TCP_MD5SIG_MAXKEYLEN
];
1300 struct rcu_head rcu
;
1304 struct tcp_md5sig_info
{
1305 struct hlist_head head
;
1306 struct rcu_head rcu
;
1309 /* - pseudo header */
1310 struct tcp4_pseudohdr
{
1318 struct tcp6_pseudohdr
{
1319 struct in6_addr saddr
;
1320 struct in6_addr daddr
;
1322 __be32 protocol
; /* including padding */
1325 union tcp_md5sum_block
{
1326 struct tcp4_pseudohdr ip4
;
1327 #if IS_ENABLED(CONFIG_IPV6)
1328 struct tcp6_pseudohdr ip6
;
1332 /* - pool: digest algorithm, hash description and scratch buffer */
1333 struct tcp_md5sig_pool
{
1334 struct hash_desc md5_desc
;
1335 union tcp_md5sum_block md5_blk
;
1339 int tcp_v4_md5_hash_skb(char *md5_hash
, const struct tcp_md5sig_key
*key
,
1340 const struct sock
*sk
, const struct sk_buff
*skb
);
1341 int tcp_md5_do_add(struct sock
*sk
, const union tcp_md5_addr
*addr
,
1342 int family
, const u8
*newkey
, u8 newkeylen
, gfp_t gfp
);
1343 int tcp_md5_do_del(struct sock
*sk
, const union tcp_md5_addr
*addr
,
1345 struct tcp_md5sig_key
*tcp_v4_md5_lookup(struct sock
*sk
,
1346 const struct sock
*addr_sk
);
1348 #ifdef CONFIG_TCP_MD5SIG
1349 struct tcp_md5sig_key
*tcp_md5_do_lookup(struct sock
*sk
,
1350 const union tcp_md5_addr
*addr
,
1352 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1354 static inline struct tcp_md5sig_key
*tcp_md5_do_lookup(struct sock
*sk
,
1355 const union tcp_md5_addr
*addr
,
1360 #define tcp_twsk_md5_key(twsk) NULL
1363 bool tcp_alloc_md5sig_pool(void);
1365 struct tcp_md5sig_pool
*tcp_get_md5sig_pool(void);
1366 static inline void tcp_put_md5sig_pool(void)
1371 int tcp_md5_hash_header(struct tcp_md5sig_pool
*, const struct tcphdr
*);
1372 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool
*, const struct sk_buff
*,
1373 unsigned int header_len
);
1374 int tcp_md5_hash_key(struct tcp_md5sig_pool
*hp
,
1375 const struct tcp_md5sig_key
*key
);
1377 /* From tcp_fastopen.c */
1378 void tcp_fastopen_cache_get(struct sock
*sk
, u16
*mss
,
1379 struct tcp_fastopen_cookie
*cookie
, int *syn_loss
,
1380 unsigned long *last_syn_loss
);
1381 void tcp_fastopen_cache_set(struct sock
*sk
, u16 mss
,
1382 struct tcp_fastopen_cookie
*cookie
, bool syn_lost
,
1384 struct tcp_fastopen_request
{
1385 /* Fast Open cookie. Size 0 means a cookie request */
1386 struct tcp_fastopen_cookie cookie
;
1387 struct msghdr
*data
; /* data in MSG_FASTOPEN */
1389 int copied
; /* queued in tcp_connect() */
1391 void tcp_free_fastopen_req(struct tcp_sock
*tp
);
1393 extern struct tcp_fastopen_context __rcu
*tcp_fastopen_ctx
;
1394 int tcp_fastopen_reset_cipher(void *key
, unsigned int len
);
1395 bool tcp_try_fastopen(struct sock
*sk
, struct sk_buff
*skb
,
1396 struct request_sock
*req
,
1397 struct tcp_fastopen_cookie
*foc
,
1398 struct dst_entry
*dst
);
1399 void tcp_fastopen_init_key_once(bool publish
);
1400 #define TCP_FASTOPEN_KEY_LENGTH 16
1402 /* Fastopen key context */
1403 struct tcp_fastopen_context
{
1404 struct crypto_cipher
*tfm
;
1405 __u8 key
[TCP_FASTOPEN_KEY_LENGTH
];
1406 struct rcu_head rcu
;
1409 /* write queue abstraction */
1410 static inline void tcp_write_queue_purge(struct sock
*sk
)
1412 struct sk_buff
*skb
;
1414 while ((skb
= __skb_dequeue(&sk
->sk_write_queue
)) != NULL
)
1415 sk_wmem_free_skb(sk
, skb
);
1417 tcp_clear_all_retrans_hints(tcp_sk(sk
));
1420 static inline struct sk_buff
*tcp_write_queue_head(const struct sock
*sk
)
1422 return skb_peek(&sk
->sk_write_queue
);
1425 static inline struct sk_buff
*tcp_write_queue_tail(const struct sock
*sk
)
1427 return skb_peek_tail(&sk
->sk_write_queue
);
1430 static inline struct sk_buff
*tcp_write_queue_next(const struct sock
*sk
,
1431 const struct sk_buff
*skb
)
1433 return skb_queue_next(&sk
->sk_write_queue
, skb
);
1436 static inline struct sk_buff
*tcp_write_queue_prev(const struct sock
*sk
,
1437 const struct sk_buff
*skb
)
1439 return skb_queue_prev(&sk
->sk_write_queue
, skb
);
1442 #define tcp_for_write_queue(skb, sk) \
1443 skb_queue_walk(&(sk)->sk_write_queue, skb)
1445 #define tcp_for_write_queue_from(skb, sk) \
1446 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1448 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1449 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1451 static inline struct sk_buff
*tcp_send_head(const struct sock
*sk
)
1453 return sk
->sk_send_head
;
1456 static inline bool tcp_skb_is_last(const struct sock
*sk
,
1457 const struct sk_buff
*skb
)
1459 return skb_queue_is_last(&sk
->sk_write_queue
, skb
);
1462 static inline void tcp_advance_send_head(struct sock
*sk
, const struct sk_buff
*skb
)
1464 if (tcp_skb_is_last(sk
, skb
))
1465 sk
->sk_send_head
= NULL
;
1467 sk
->sk_send_head
= tcp_write_queue_next(sk
, skb
);
1470 static inline void tcp_check_send_head(struct sock
*sk
, struct sk_buff
*skb_unlinked
)
1472 if (sk
->sk_send_head
== skb_unlinked
)
1473 sk
->sk_send_head
= NULL
;
1476 static inline void tcp_init_send_head(struct sock
*sk
)
1478 sk
->sk_send_head
= NULL
;
1481 static inline void __tcp_add_write_queue_tail(struct sock
*sk
, struct sk_buff
*skb
)
1483 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
1486 static inline void tcp_add_write_queue_tail(struct sock
*sk
, struct sk_buff
*skb
)
1488 __tcp_add_write_queue_tail(sk
, skb
);
1490 /* Queue it, remembering where we must start sending. */
1491 if (sk
->sk_send_head
== NULL
) {
1492 sk
->sk_send_head
= skb
;
1494 if (tcp_sk(sk
)->highest_sack
== NULL
)
1495 tcp_sk(sk
)->highest_sack
= skb
;
1499 static inline void __tcp_add_write_queue_head(struct sock
*sk
, struct sk_buff
*skb
)
1501 __skb_queue_head(&sk
->sk_write_queue
, skb
);
1504 /* Insert buff after skb on the write queue of sk. */
1505 static inline void tcp_insert_write_queue_after(struct sk_buff
*skb
,
1506 struct sk_buff
*buff
,
1509 __skb_queue_after(&sk
->sk_write_queue
, skb
, buff
);
1512 /* Insert new before skb on the write queue of sk. */
1513 static inline void tcp_insert_write_queue_before(struct sk_buff
*new,
1514 struct sk_buff
*skb
,
1517 __skb_queue_before(&sk
->sk_write_queue
, skb
, new);
1519 if (sk
->sk_send_head
== skb
)
1520 sk
->sk_send_head
= new;
1523 static inline void tcp_unlink_write_queue(struct sk_buff
*skb
, struct sock
*sk
)
1525 __skb_unlink(skb
, &sk
->sk_write_queue
);
1528 static inline bool tcp_write_queue_empty(struct sock
*sk
)
1530 return skb_queue_empty(&sk
->sk_write_queue
);
1533 static inline void tcp_push_pending_frames(struct sock
*sk
)
1535 if (tcp_send_head(sk
)) {
1536 struct tcp_sock
*tp
= tcp_sk(sk
);
1538 __tcp_push_pending_frames(sk
, tcp_current_mss(sk
), tp
->nonagle
);
1542 /* Start sequence of the skb just after the highest skb with SACKed
1543 * bit, valid only if sacked_out > 0 or when the caller has ensured
1544 * validity by itself.
1546 static inline u32
tcp_highest_sack_seq(struct tcp_sock
*tp
)
1548 if (!tp
->sacked_out
)
1551 if (tp
->highest_sack
== NULL
)
1554 return TCP_SKB_CB(tp
->highest_sack
)->seq
;
1557 static inline void tcp_advance_highest_sack(struct sock
*sk
, struct sk_buff
*skb
)
1559 tcp_sk(sk
)->highest_sack
= tcp_skb_is_last(sk
, skb
) ? NULL
:
1560 tcp_write_queue_next(sk
, skb
);
1563 static inline struct sk_buff
*tcp_highest_sack(struct sock
*sk
)
1565 return tcp_sk(sk
)->highest_sack
;
1568 static inline void tcp_highest_sack_reset(struct sock
*sk
)
1570 tcp_sk(sk
)->highest_sack
= tcp_write_queue_head(sk
);
1573 /* Called when old skb is about to be deleted (to be combined with new skb) */
1574 static inline void tcp_highest_sack_combine(struct sock
*sk
,
1575 struct sk_buff
*old
,
1576 struct sk_buff
*new)
1578 if (tcp_sk(sk
)->sacked_out
&& (old
== tcp_sk(sk
)->highest_sack
))
1579 tcp_sk(sk
)->highest_sack
= new;
1582 /* Determines whether this is a thin stream (which may suffer from
1583 * increased latency). Used to trigger latency-reducing mechanisms.
1585 static inline bool tcp_stream_is_thin(struct tcp_sock
*tp
)
1587 return tp
->packets_out
< 4 && !tcp_in_initial_slowstart(tp
);
1591 enum tcp_seq_states
{
1592 TCP_SEQ_STATE_LISTENING
,
1593 TCP_SEQ_STATE_OPENREQ
,
1594 TCP_SEQ_STATE_ESTABLISHED
,
1597 int tcp_seq_open(struct inode
*inode
, struct file
*file
);
1599 struct tcp_seq_afinfo
{
1602 const struct file_operations
*seq_fops
;
1603 struct seq_operations seq_ops
;
1606 struct tcp_iter_state
{
1607 struct seq_net_private p
;
1609 enum tcp_seq_states state
;
1610 struct sock
*syn_wait_sk
;
1611 int bucket
, offset
, sbucket
, num
;
1616 int tcp_proc_register(struct net
*net
, struct tcp_seq_afinfo
*afinfo
);
1617 void tcp_proc_unregister(struct net
*net
, struct tcp_seq_afinfo
*afinfo
);
1619 extern struct request_sock_ops tcp_request_sock_ops
;
1620 extern struct request_sock_ops tcp6_request_sock_ops
;
1622 void tcp_v4_destroy_sock(struct sock
*sk
);
1624 struct sk_buff
*tcp_gso_segment(struct sk_buff
*skb
,
1625 netdev_features_t features
);
1626 struct sk_buff
**tcp_gro_receive(struct sk_buff
**head
, struct sk_buff
*skb
);
1627 int tcp_gro_complete(struct sk_buff
*skb
);
1629 void __tcp_v4_send_check(struct sk_buff
*skb
, __be32 saddr
, __be32 daddr
);
1631 static inline u32
tcp_notsent_lowat(const struct tcp_sock
*tp
)
1633 return tp
->notsent_lowat
?: sysctl_tcp_notsent_lowat
;
1636 static inline bool tcp_stream_memory_free(const struct sock
*sk
)
1638 const struct tcp_sock
*tp
= tcp_sk(sk
);
1639 u32 notsent_bytes
= tp
->write_seq
- tp
->snd_nxt
;
1641 return notsent_bytes
< tcp_notsent_lowat(tp
);
1644 #ifdef CONFIG_PROC_FS
1645 int tcp4_proc_init(void);
1646 void tcp4_proc_exit(void);
1649 int tcp_rtx_synack(struct sock
*sk
, struct request_sock
*req
);
1650 int tcp_conn_request(struct request_sock_ops
*rsk_ops
,
1651 const struct tcp_request_sock_ops
*af_ops
,
1652 struct sock
*sk
, struct sk_buff
*skb
);
1654 /* TCP af-specific functions */
1655 struct tcp_sock_af_ops
{
1656 #ifdef CONFIG_TCP_MD5SIG
1657 struct tcp_md5sig_key
*(*md5_lookup
) (struct sock
*sk
,
1658 const struct sock
*addr_sk
);
1659 int (*calc_md5_hash
)(char *location
,
1660 const struct tcp_md5sig_key
*md5
,
1661 const struct sock
*sk
,
1662 const struct sk_buff
*skb
);
1663 int (*md5_parse
)(struct sock
*sk
,
1664 char __user
*optval
,
1669 struct tcp_request_sock_ops
{
1671 #ifdef CONFIG_TCP_MD5SIG
1672 struct tcp_md5sig_key
*(*req_md5_lookup
)(struct sock
*sk
,
1673 const struct sock
*addr_sk
);
1674 int (*calc_md5_hash
) (char *location
,
1675 const struct tcp_md5sig_key
*md5
,
1676 const struct sock
*sk
,
1677 const struct sk_buff
*skb
);
1679 void (*init_req
)(struct request_sock
*req
, struct sock
*sk
,
1680 struct sk_buff
*skb
);
1681 #ifdef CONFIG_SYN_COOKIES
1682 __u32 (*cookie_init_seq
)(struct sock
*sk
, const struct sk_buff
*skb
,
1685 struct dst_entry
*(*route_req
)(struct sock
*sk
, struct flowi
*fl
,
1686 const struct request_sock
*req
,
1688 __u32 (*init_seq
)(const struct sk_buff
*skb
);
1689 int (*send_synack
)(struct sock
*sk
, struct dst_entry
*dst
,
1690 struct flowi
*fl
, struct request_sock
*req
,
1691 u16 queue_mapping
, struct tcp_fastopen_cookie
*foc
);
1692 void (*queue_hash_add
)(struct sock
*sk
, struct request_sock
*req
,
1693 const unsigned long timeout
);
1696 #ifdef CONFIG_SYN_COOKIES
1697 static inline __u32
cookie_init_sequence(const struct tcp_request_sock_ops
*ops
,
1698 struct sock
*sk
, struct sk_buff
*skb
,
1701 return ops
->cookie_init_seq(sk
, skb
, mss
);
1704 static inline __u32
cookie_init_sequence(const struct tcp_request_sock_ops
*ops
,
1705 struct sock
*sk
, struct sk_buff
*skb
,
1712 int tcpv4_offload_init(void);
1714 void tcp_v4_init(void);
1715 void tcp_init(void);
1718 * Save and compile IPv4 options, return a pointer to it
1720 static inline struct ip_options_rcu
*tcp_v4_save_options(struct sk_buff
*skb
)
1722 const struct ip_options
*opt
= &TCP_SKB_CB(skb
)->header
.h4
.opt
;
1723 struct ip_options_rcu
*dopt
= NULL
;
1726 int opt_size
= sizeof(*dopt
) + opt
->optlen
;
1728 dopt
= kmalloc(opt_size
, GFP_ATOMIC
);
1729 if (dopt
&& __ip_options_echo(&dopt
->opt
, skb
, opt
)) {
1737 /* locally generated TCP pure ACKs have skb->truesize == 2
1738 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1739 * This is much faster than dissecting the packet to find out.
1740 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1742 static inline bool skb_is_tcp_pure_ack(const struct sk_buff
*skb
)
1744 return skb
->truesize
== 2;
1747 static inline void skb_set_tcp_pure_ack(struct sk_buff
*skb
)