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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 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
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.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define FASTRETRANS_DEBUG 1
22
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/cryptohash.h>
31#include <linux/kref.h>
32#include <linux/ktime.h>
33
34#include <net/inet_connection_sock.h>
35#include <net/inet_timewait_sock.h>
36#include <net/inet_hashtables.h>
37#include <net/checksum.h>
38#include <net/request_sock.h>
39#include <net/sock.h>
40#include <net/snmp.h>
41#include <net/ip.h>
42#include <net/tcp_states.h>
43#include <net/inet_ecn.h>
44#include <net/dst.h>
45
46#include <linux/seq_file.h>
47#include <linux/memcontrol.h>
48
49#include <linux/bpf.h>
50#include <linux/filter.h>
51#include <linux/bpf-cgroup.h>
52
53extern struct inet_hashinfo tcp_hashinfo;
54
55extern struct percpu_counter tcp_orphan_count;
56void tcp_time_wait(struct sock *sk, int state, int timeo);
57
58#define MAX_TCP_HEADER (128 + MAX_HEADER)
59#define MAX_TCP_OPTION_SPACE 40
60
61/*
62 * Never offer a window over 32767 without using window scaling. Some
63 * poor stacks do signed 16bit maths!
64 */
65#define MAX_TCP_WINDOW 32767U
66
67/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68#define TCP_MIN_MSS 88U
69
70/* The least MTU to use for probing */
71#define TCP_BASE_MSS 1024
72
73/* probing interval, default to 10 minutes as per RFC4821 */
74#define TCP_PROBE_INTERVAL 600
75
76/* Specify interval when tcp mtu probing will stop */
77#define TCP_PROBE_THRESHOLD 8
78
79/* After receiving this amount of duplicate ACKs fast retransmit starts. */
80#define TCP_FASTRETRANS_THRESH 3
81
82/* Maximal number of ACKs sent quickly to accelerate slow-start. */
83#define TCP_MAX_QUICKACKS 16U
84
85/* Maximal number of window scale according to RFC1323 */
86#define TCP_MAX_WSCALE 14U
87
88/* urg_data states */
89#define TCP_URG_VALID 0x0100
90#define TCP_URG_NOTYET 0x0200
91#define TCP_URG_READ 0x0400
92
93#define TCP_RETR1 3 /*
94 * This is how many retries it does before it
95 * tries to figure out if the gateway is
96 * down. Minimal RFC value is 3; it corresponds
97 * to ~3sec-8min depending on RTO.
98 */
99
100#define TCP_RETR2 15 /*
101 * This should take at least
102 * 90 minutes to time out.
103 * RFC1122 says that the limit is 100 sec.
104 * 15 is ~13-30min depending on RTO.
105 */
106
107#define TCP_SYN_RETRIES 6 /* This is how many retries are done
108 * when active opening a connection.
109 * RFC1122 says the minimum retry MUST
110 * be at least 180secs. Nevertheless
111 * this value is corresponding to
112 * 63secs of retransmission with the
113 * current initial RTO.
114 */
115
116#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
117 * when passive opening a connection.
118 * This is corresponding to 31secs of
119 * retransmission with the current
120 * initial RTO.
121 */
122
123#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
124 * state, about 60 seconds */
125#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
126 /* BSD style FIN_WAIT2 deadlock breaker.
127 * It used to be 3min, new value is 60sec,
128 * to combine FIN-WAIT-2 timeout with
129 * TIME-WAIT timer.
130 */
131
132#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
133#if HZ >= 100
134#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
135#define TCP_ATO_MIN ((unsigned)(HZ/25))
136#else
137#define TCP_DELACK_MIN 4U
138#define TCP_ATO_MIN 4U
139#endif
140#define TCP_RTO_MAX ((unsigned)(120*HZ))
141#define TCP_RTO_MIN ((unsigned)(HZ/5))
142#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
143#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
144 * used as a fallback RTO for the
145 * initial data transmission if no
146 * valid RTT sample has been acquired,
147 * most likely due to retrans in 3WHS.
148 */
149
150#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
151 * for local resources.
152 */
153#define TCP_REO_TIMEOUT_MIN (2000) /* Min RACK reordering timeout in usec */
154
155#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
156#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
157#define TCP_KEEPALIVE_INTVL (75*HZ)
158
159#define MAX_TCP_KEEPIDLE 32767
160#define MAX_TCP_KEEPINTVL 32767
161#define MAX_TCP_KEEPCNT 127
162#define MAX_TCP_SYNCNT 127
163
164#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
165
166#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
167#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
168 * after this time. It should be equal
169 * (or greater than) TCP_TIMEWAIT_LEN
170 * to provide reliability equal to one
171 * provided by timewait state.
172 */
173#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
174 * timestamps. It must be less than
175 * minimal timewait lifetime.
176 */
177/*
178 * TCP option
179 */
180
181#define TCPOPT_NOP 1 /* Padding */
182#define TCPOPT_EOL 0 /* End of options */
183#define TCPOPT_MSS 2 /* Segment size negotiating */
184#define TCPOPT_WINDOW 3 /* Window scaling */
185#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
186#define TCPOPT_SACK 5 /* SACK Block */
187#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
188#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
189#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
190#define TCPOPT_EXP 254 /* Experimental */
191/* Magic number to be after the option value for sharing TCP
192 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
193 */
194#define TCPOPT_FASTOPEN_MAGIC 0xF989
195
196/*
197 * TCP option lengths
198 */
199
200#define TCPOLEN_MSS 4
201#define TCPOLEN_WINDOW 3
202#define TCPOLEN_SACK_PERM 2
203#define TCPOLEN_TIMESTAMP 10
204#define TCPOLEN_MD5SIG 18
205#define TCPOLEN_FASTOPEN_BASE 2
206#define TCPOLEN_EXP_FASTOPEN_BASE 4
207
208/* But this is what stacks really send out. */
209#define TCPOLEN_TSTAMP_ALIGNED 12
210#define TCPOLEN_WSCALE_ALIGNED 4
211#define TCPOLEN_SACKPERM_ALIGNED 4
212#define TCPOLEN_SACK_BASE 2
213#define TCPOLEN_SACK_BASE_ALIGNED 4
214#define TCPOLEN_SACK_PERBLOCK 8
215#define TCPOLEN_MD5SIG_ALIGNED 20
216#define TCPOLEN_MSS_ALIGNED 4
217
218/* Flags in tp->nonagle */
219#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
220#define TCP_NAGLE_CORK 2 /* Socket is corked */
221#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
222
223/* TCP thin-stream limits */
224#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
225
226/* TCP initial congestion window as per rfc6928 */
227#define TCP_INIT_CWND 10
228
229/* Bit Flags for sysctl_tcp_fastopen */
230#define TFO_CLIENT_ENABLE 1
231#define TFO_SERVER_ENABLE 2
232#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
233
234/* Accept SYN data w/o any cookie option */
235#define TFO_SERVER_COOKIE_NOT_REQD 0x200
236
237/* Force enable TFO on all listeners, i.e., not requiring the
238 * TCP_FASTOPEN socket option.
239 */
240#define TFO_SERVER_WO_SOCKOPT1 0x400
241
242
243/* sysctl variables for tcp */
244extern int sysctl_tcp_fastopen;
245extern int sysctl_tcp_retrans_collapse;
246extern int sysctl_tcp_stdurg;
247extern int sysctl_tcp_rfc1337;
248extern int sysctl_tcp_abort_on_overflow;
249extern int sysctl_tcp_max_orphans;
250extern int sysctl_tcp_fack;
251extern int sysctl_tcp_reordering;
252extern int sysctl_tcp_max_reordering;
253extern int sysctl_tcp_dsack;
254extern long sysctl_tcp_mem[3];
255extern int sysctl_tcp_wmem[3];
256extern int sysctl_tcp_rmem[3];
257extern int sysctl_tcp_app_win;
258extern int sysctl_tcp_adv_win_scale;
259extern int sysctl_tcp_frto;
260extern int sysctl_tcp_low_latency;
261extern int sysctl_tcp_nometrics_save;
262extern int sysctl_tcp_moderate_rcvbuf;
263extern int sysctl_tcp_tso_win_divisor;
264extern int sysctl_tcp_workaround_signed_windows;
265extern int sysctl_tcp_slow_start_after_idle;
266extern int sysctl_tcp_thin_linear_timeouts;
267extern int sysctl_tcp_thin_dupack;
268extern int sysctl_tcp_early_retrans;
269extern int sysctl_tcp_recovery;
270#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
271
272extern int sysctl_tcp_limit_output_bytes;
273extern int sysctl_tcp_challenge_ack_limit;
274extern int sysctl_tcp_min_tso_segs;
275extern int sysctl_tcp_min_rtt_wlen;
276extern int sysctl_tcp_autocorking;
277extern int sysctl_tcp_invalid_ratelimit;
278extern int sysctl_tcp_pacing_ss_ratio;
279extern int sysctl_tcp_pacing_ca_ratio;
280
281extern atomic_long_t tcp_memory_allocated;
282extern struct percpu_counter tcp_sockets_allocated;
283extern unsigned long tcp_memory_pressure;
284
285/* optimized version of sk_under_memory_pressure() for TCP sockets */
286static inline bool tcp_under_memory_pressure(const struct sock *sk)
287{
288 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
289 mem_cgroup_under_socket_pressure(sk->sk_memcg))
290 return true;
291
292 return tcp_memory_pressure;
293}
294/*
295 * The next routines deal with comparing 32 bit unsigned ints
296 * and worry about wraparound (automatic with unsigned arithmetic).
297 */
298
299static inline bool before(__u32 seq1, __u32 seq2)
300{
301 return (__s32)(seq1-seq2) < 0;
302}
303#define after(seq2, seq1) before(seq1, seq2)
304
305/* is s2<=s1<=s3 ? */
306static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
307{
308 return seq3 - seq2 >= seq1 - seq2;
309}
310
311static inline bool tcp_out_of_memory(struct sock *sk)
312{
313 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
314 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
315 return true;
316 return false;
317}
318
319void sk_forced_mem_schedule(struct sock *sk, int size);
320
321static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
322{
323 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
324 int orphans = percpu_counter_read_positive(ocp);
325
326 if (orphans << shift > sysctl_tcp_max_orphans) {
327 orphans = percpu_counter_sum_positive(ocp);
328 if (orphans << shift > sysctl_tcp_max_orphans)
329 return true;
330 }
331 return false;
332}
333
334bool tcp_check_oom(struct sock *sk, int shift);
335
336
337extern struct proto tcp_prot;
338
339#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
340#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
341#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
342#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
343
344void tcp_tasklet_init(void);
345
346void tcp_v4_err(struct sk_buff *skb, u32);
347
348void tcp_shutdown(struct sock *sk, int how);
349
350int tcp_v4_early_demux(struct sk_buff *skb);
351int tcp_v4_rcv(struct sk_buff *skb);
352
353int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
354int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
355int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
356 int flags);
357ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
358 size_t size, int flags);
359void tcp_release_cb(struct sock *sk);
360void tcp_wfree(struct sk_buff *skb);
361void tcp_write_timer_handler(struct sock *sk);
362void tcp_delack_timer_handler(struct sock *sk);
363int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
364int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
365void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
366 const struct tcphdr *th, unsigned int len);
367void tcp_rcv_space_adjust(struct sock *sk);
368int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
369void tcp_twsk_destructor(struct sock *sk);
370ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
371 struct pipe_inode_info *pipe, size_t len,
372 unsigned int flags);
373
374static inline void tcp_dec_quickack_mode(struct sock *sk,
375 const unsigned int pkts)
376{
377 struct inet_connection_sock *icsk = inet_csk(sk);
378
379 if (icsk->icsk_ack.quick) {
380 if (pkts >= icsk->icsk_ack.quick) {
381 icsk->icsk_ack.quick = 0;
382 /* Leaving quickack mode we deflate ATO. */
383 icsk->icsk_ack.ato = TCP_ATO_MIN;
384 } else
385 icsk->icsk_ack.quick -= pkts;
386 }
387}
388
389#define TCP_ECN_OK 1
390#define TCP_ECN_QUEUE_CWR 2
391#define TCP_ECN_DEMAND_CWR 4
392#define TCP_ECN_SEEN 8
393
394enum tcp_tw_status {
395 TCP_TW_SUCCESS = 0,
396 TCP_TW_RST = 1,
397 TCP_TW_ACK = 2,
398 TCP_TW_SYN = 3
399};
400
401
402enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
403 struct sk_buff *skb,
404 const struct tcphdr *th);
405struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
406 struct request_sock *req, bool fastopen);
407int tcp_child_process(struct sock *parent, struct sock *child,
408 struct sk_buff *skb);
409void tcp_enter_loss(struct sock *sk);
410void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
411void tcp_clear_retrans(struct tcp_sock *tp);
412void tcp_update_metrics(struct sock *sk);
413void tcp_init_metrics(struct sock *sk);
414void tcp_metrics_init(void);
415bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
416void tcp_disable_fack(struct tcp_sock *tp);
417void tcp_close(struct sock *sk, long timeout);
418void tcp_init_sock(struct sock *sk);
419unsigned int tcp_poll(struct file *file, struct socket *sock,
420 struct poll_table_struct *wait);
421int tcp_getsockopt(struct sock *sk, int level, int optname,
422 char __user *optval, int __user *optlen);
423int tcp_setsockopt(struct sock *sk, int level, int optname,
424 char __user *optval, unsigned int optlen);
425int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
426 char __user *optval, int __user *optlen);
427int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
428 char __user *optval, unsigned int optlen);
429void tcp_set_keepalive(struct sock *sk, int val);
430void tcp_syn_ack_timeout(const struct request_sock *req);
431int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
432 int flags, int *addr_len);
433void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
434 struct tcp_options_received *opt_rx,
435 int estab, struct tcp_fastopen_cookie *foc);
436const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
437
438/*
439 * TCP v4 functions exported for the inet6 API
440 */
441
442void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
443void tcp_v4_mtu_reduced(struct sock *sk);
444void tcp_req_err(struct sock *sk, u32 seq, bool abort);
445int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
446struct sock *tcp_create_openreq_child(const struct sock *sk,
447 struct request_sock *req,
448 struct sk_buff *skb);
449void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
450struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
451 struct request_sock *req,
452 struct dst_entry *dst,
453 struct request_sock *req_unhash,
454 bool *own_req);
455int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
456int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
457int tcp_connect(struct sock *sk);
458enum tcp_synack_type {
459 TCP_SYNACK_NORMAL,
460 TCP_SYNACK_FASTOPEN,
461 TCP_SYNACK_COOKIE,
462};
463struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
464 struct request_sock *req,
465 struct tcp_fastopen_cookie *foc,
466 enum tcp_synack_type synack_type);
467int tcp_disconnect(struct sock *sk, int flags);
468
469void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
470int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
471void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
472
473/* From syncookies.c */
474struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
475 struct request_sock *req,
476 struct dst_entry *dst, u32 tsoff);
477int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
478 u32 cookie);
479struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
480#ifdef CONFIG_SYN_COOKIES
481
482/* Syncookies use a monotonic timer which increments every 60 seconds.
483 * This counter is used both as a hash input and partially encoded into
484 * the cookie value. A cookie is only validated further if the delta
485 * between the current counter value and the encoded one is less than this,
486 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
487 * the counter advances immediately after a cookie is generated).
488 */
489#define MAX_SYNCOOKIE_AGE 2
490#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
491#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
492
493/* syncookies: remember time of last synqueue overflow
494 * But do not dirty this field too often (once per second is enough)
495 * It is racy as we do not hold a lock, but race is very minor.
496 */
497static inline void tcp_synq_overflow(const struct sock *sk)
498{
499 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
500 unsigned long now = jiffies;
501
502 if (time_after(now, last_overflow + HZ))
503 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
504}
505
506/* syncookies: no recent synqueue overflow on this listening socket? */
507static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
508{
509 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
510
511 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
512}
513
514static inline u32 tcp_cookie_time(void)
515{
516 u64 val = get_jiffies_64();
517
518 do_div(val, TCP_SYNCOOKIE_PERIOD);
519 return val;
520}
521
522u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
523 u16 *mssp);
524__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
525u64 cookie_init_timestamp(struct request_sock *req);
526bool cookie_timestamp_decode(const struct net *net,
527 struct tcp_options_received *opt);
528bool cookie_ecn_ok(const struct tcp_options_received *opt,
529 const struct net *net, const struct dst_entry *dst);
530
531/* From net/ipv6/syncookies.c */
532int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
533 u32 cookie);
534struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
535
536u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
537 const struct tcphdr *th, u16 *mssp);
538__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
539#endif
540/* tcp_output.c */
541
542u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
543 int min_tso_segs);
544void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
545 int nonagle);
546bool tcp_may_send_now(struct sock *sk);
547int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
548int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
549void tcp_retransmit_timer(struct sock *sk);
550void tcp_xmit_retransmit_queue(struct sock *);
551void tcp_simple_retransmit(struct sock *);
552void tcp_enter_recovery(struct sock *sk, bool ece_ack);
553int tcp_trim_head(struct sock *, struct sk_buff *, u32);
554int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
555
556void tcp_send_probe0(struct sock *);
557void tcp_send_partial(struct sock *);
558int tcp_write_wakeup(struct sock *, int mib);
559void tcp_send_fin(struct sock *sk);
560void tcp_send_active_reset(struct sock *sk, gfp_t priority);
561int tcp_send_synack(struct sock *);
562void tcp_push_one(struct sock *, unsigned int mss_now);
563void tcp_send_ack(struct sock *sk);
564void tcp_send_delayed_ack(struct sock *sk);
565void tcp_send_loss_probe(struct sock *sk);
566bool tcp_schedule_loss_probe(struct sock *sk);
567void tcp_skb_collapse_tstamp(struct sk_buff *skb,
568 const struct sk_buff *next_skb);
569
570/* tcp_input.c */
571void tcp_rearm_rto(struct sock *sk);
572void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
573void tcp_reset(struct sock *sk);
574void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
575void tcp_fin(struct sock *sk);
576
577/* tcp_timer.c */
578void tcp_init_xmit_timers(struct sock *);
579static inline void tcp_clear_xmit_timers(struct sock *sk)
580{
581 hrtimer_cancel(&tcp_sk(sk)->pacing_timer);
582 inet_csk_clear_xmit_timers(sk);
583}
584
585unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
586unsigned int tcp_current_mss(struct sock *sk);
587
588/* Bound MSS / TSO packet size with the half of the window */
589static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
590{
591 int cutoff;
592
593 /* When peer uses tiny windows, there is no use in packetizing
594 * to sub-MSS pieces for the sake of SWS or making sure there
595 * are enough packets in the pipe for fast recovery.
596 *
597 * On the other hand, for extremely large MSS devices, handling
598 * smaller than MSS windows in this way does make sense.
599 */
600 if (tp->max_window > TCP_MSS_DEFAULT)
601 cutoff = (tp->max_window >> 1);
602 else
603 cutoff = tp->max_window;
604
605 if (cutoff && pktsize > cutoff)
606 return max_t(int, cutoff, 68U - tp->tcp_header_len);
607 else
608 return pktsize;
609}
610
611/* tcp.c */
612void tcp_get_info(struct sock *, struct tcp_info *);
613
614/* Read 'sendfile()'-style from a TCP socket */
615int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
616 sk_read_actor_t recv_actor);
617
618void tcp_initialize_rcv_mss(struct sock *sk);
619
620int tcp_mtu_to_mss(struct sock *sk, int pmtu);
621int tcp_mss_to_mtu(struct sock *sk, int mss);
622void tcp_mtup_init(struct sock *sk);
623void tcp_init_buffer_space(struct sock *sk);
624
625static inline void tcp_bound_rto(const struct sock *sk)
626{
627 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
628 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
629}
630
631static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
632{
633 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
634}
635
636static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
637{
638 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
639 ntohl(TCP_FLAG_ACK) |
640 snd_wnd);
641}
642
643static inline void tcp_fast_path_on(struct tcp_sock *tp)
644{
645 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
646}
647
648static inline void tcp_fast_path_check(struct sock *sk)
649{
650 struct tcp_sock *tp = tcp_sk(sk);
651
652 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
653 tp->rcv_wnd &&
654 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
655 !tp->urg_data)
656 tcp_fast_path_on(tp);
657}
658
659/* Compute the actual rto_min value */
660static inline u32 tcp_rto_min(struct sock *sk)
661{
662 const struct dst_entry *dst = __sk_dst_get(sk);
663 u32 rto_min = TCP_RTO_MIN;
664
665 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
666 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
667 return rto_min;
668}
669
670static inline u32 tcp_rto_min_us(struct sock *sk)
671{
672 return jiffies_to_usecs(tcp_rto_min(sk));
673}
674
675static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
676{
677 return dst_metric_locked(dst, RTAX_CC_ALGO);
678}
679
680/* Minimum RTT in usec. ~0 means not available. */
681static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
682{
683 return minmax_get(&tp->rtt_min);
684}
685
686/* Compute the actual receive window we are currently advertising.
687 * Rcv_nxt can be after the window if our peer push more data
688 * than the offered window.
689 */
690static inline u32 tcp_receive_window(const struct tcp_sock *tp)
691{
692 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
693
694 if (win < 0)
695 win = 0;
696 return (u32) win;
697}
698
699/* Choose a new window, without checks for shrinking, and without
700 * scaling applied to the result. The caller does these things
701 * if necessary. This is a "raw" window selection.
702 */
703u32 __tcp_select_window(struct sock *sk);
704
705void tcp_send_window_probe(struct sock *sk);
706
707/* TCP uses 32bit jiffies to save some space.
708 * Note that this is different from tcp_time_stamp, which
709 * historically has been the same until linux-4.13.
710 */
711#define tcp_jiffies32 ((u32)jiffies)
712
713/*
714 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
715 * It is no longer tied to jiffies, but to 1 ms clock.
716 * Note: double check if you want to use tcp_jiffies32 instead of this.
717 */
718#define TCP_TS_HZ 1000
719
720static inline u64 tcp_clock_ns(void)
721{
722 return local_clock();
723}
724
725static inline u64 tcp_clock_us(void)
726{
727 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
728}
729
730/* This should only be used in contexts where tp->tcp_mstamp is up to date */
731static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
732{
733 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
734}
735
736/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
737static inline u32 tcp_time_stamp_raw(void)
738{
739 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
740}
741
742
743/* Refresh 1us clock of a TCP socket,
744 * ensuring monotically increasing values.
745 */
746static inline void tcp_mstamp_refresh(struct tcp_sock *tp)
747{
748 u64 val = tcp_clock_us();
749
750 if (val > tp->tcp_mstamp)
751 tp->tcp_mstamp = val;
752}
753
754static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
755{
756 return max_t(s64, t1 - t0, 0);
757}
758
759static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
760{
761 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ);
762}
763
764
765#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
766
767#define TCPHDR_FIN 0x01
768#define TCPHDR_SYN 0x02
769#define TCPHDR_RST 0x04
770#define TCPHDR_PSH 0x08
771#define TCPHDR_ACK 0x10
772#define TCPHDR_URG 0x20
773#define TCPHDR_ECE 0x40
774#define TCPHDR_CWR 0x80
775
776#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
777
778/* This is what the send packet queuing engine uses to pass
779 * TCP per-packet control information to the transmission code.
780 * We also store the host-order sequence numbers in here too.
781 * This is 44 bytes if IPV6 is enabled.
782 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
783 */
784struct tcp_skb_cb {
785 __u32 seq; /* Starting sequence number */
786 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
787 union {
788 /* Note : tcp_tw_isn is used in input path only
789 * (isn chosen by tcp_timewait_state_process())
790 *
791 * tcp_gso_segs/size are used in write queue only,
792 * cf tcp_skb_pcount()/tcp_skb_mss()
793 */
794 __u32 tcp_tw_isn;
795 struct {
796 u16 tcp_gso_segs;
797 u16 tcp_gso_size;
798 };
799 };
800 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
801
802 __u8 sacked; /* State flags for SACK/FACK. */
803#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
804#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
805#define TCPCB_LOST 0x04 /* SKB is lost */
806#define TCPCB_TAGBITS 0x07 /* All tag bits */
807#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
808#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
809#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
810 TCPCB_REPAIRED)
811
812 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
813 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
814 eor:1, /* Is skb MSG_EOR marked? */
815 unused:6;
816 __u32 ack_seq; /* Sequence number ACK'd */
817 union {
818 struct {
819 /* There is space for up to 24 bytes */
820 __u32 in_flight:30,/* Bytes in flight at transmit */
821 is_app_limited:1, /* cwnd not fully used? */
822 unused:1;
823 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
824 __u32 delivered;
825 /* start of send pipeline phase */
826 u64 first_tx_mstamp;
827 /* when we reached the "delivered" count */
828 u64 delivered_mstamp;
829 } tx; /* only used for outgoing skbs */
830 union {
831 struct inet_skb_parm h4;
832#if IS_ENABLED(CONFIG_IPV6)
833 struct inet6_skb_parm h6;
834#endif
835 } header; /* For incoming skbs */
836 };
837};
838
839#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
840
841
842#if IS_ENABLED(CONFIG_IPV6)
843/* This is the variant of inet6_iif() that must be used by TCP,
844 * as TCP moves IP6CB into a different location in skb->cb[]
845 */
846static inline int tcp_v6_iif(const struct sk_buff *skb)
847{
848 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
849
850 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
851}
852#endif
853
854/* TCP_SKB_CB reference means this can not be used from early demux */
855static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
856{
857#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
858 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
859 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
860 return true;
861#endif
862 return false;
863}
864
865/* Due to TSO, an SKB can be composed of multiple actual
866 * packets. To keep these tracked properly, we use this.
867 */
868static inline int tcp_skb_pcount(const struct sk_buff *skb)
869{
870 return TCP_SKB_CB(skb)->tcp_gso_segs;
871}
872
873static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
874{
875 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
876}
877
878static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
879{
880 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
881}
882
883/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
884static inline int tcp_skb_mss(const struct sk_buff *skb)
885{
886 return TCP_SKB_CB(skb)->tcp_gso_size;
887}
888
889static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
890{
891 return likely(!TCP_SKB_CB(skb)->eor);
892}
893
894/* Events passed to congestion control interface */
895enum tcp_ca_event {
896 CA_EVENT_TX_START, /* first transmit when no packets in flight */
897 CA_EVENT_CWND_RESTART, /* congestion window restart */
898 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
899 CA_EVENT_LOSS, /* loss timeout */
900 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
901 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
902 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
903 CA_EVENT_NON_DELAYED_ACK,
904};
905
906/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
907enum tcp_ca_ack_event_flags {
908 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
909 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
910 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
911};
912
913/*
914 * Interface for adding new TCP congestion control handlers
915 */
916#define TCP_CA_NAME_MAX 16
917#define TCP_CA_MAX 128
918#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
919
920#define TCP_CA_UNSPEC 0
921
922/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
923#define TCP_CONG_NON_RESTRICTED 0x1
924/* Requires ECN/ECT set on all packets */
925#define TCP_CONG_NEEDS_ECN 0x2
926
927union tcp_cc_info;
928
929struct ack_sample {
930 u32 pkts_acked;
931 s32 rtt_us;
932 u32 in_flight;
933};
934
935/* A rate sample measures the number of (original/retransmitted) data
936 * packets delivered "delivered" over an interval of time "interval_us".
937 * The tcp_rate.c code fills in the rate sample, and congestion
938 * control modules that define a cong_control function to run at the end
939 * of ACK processing can optionally chose to consult this sample when
940 * setting cwnd and pacing rate.
941 * A sample is invalid if "delivered" or "interval_us" is negative.
942 */
943struct rate_sample {
944 u64 prior_mstamp; /* starting timestamp for interval */
945 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
946 s32 delivered; /* number of packets delivered over interval */
947 long interval_us; /* time for tp->delivered to incr "delivered" */
948 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
949 int losses; /* number of packets marked lost upon ACK */
950 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
951 u32 prior_in_flight; /* in flight before this ACK */
952 bool is_app_limited; /* is sample from packet with bubble in pipe? */
953 bool is_retrans; /* is sample from retransmission? */
954};
955
956struct tcp_congestion_ops {
957 struct list_head list;
958 u32 key;
959 u32 flags;
960
961 /* initialize private data (optional) */
962 void (*init)(struct sock *sk);
963 /* cleanup private data (optional) */
964 void (*release)(struct sock *sk);
965
966 /* return slow start threshold (required) */
967 u32 (*ssthresh)(struct sock *sk);
968 /* do new cwnd calculation (required) */
969 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
970 /* call before changing ca_state (optional) */
971 void (*set_state)(struct sock *sk, u8 new_state);
972 /* call when cwnd event occurs (optional) */
973 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
974 /* call when ack arrives (optional) */
975 void (*in_ack_event)(struct sock *sk, u32 flags);
976 /* new value of cwnd after loss (required) */
977 u32 (*undo_cwnd)(struct sock *sk);
978 /* hook for packet ack accounting (optional) */
979 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
980 /* suggest number of segments for each skb to transmit (optional) */
981 u32 (*tso_segs_goal)(struct sock *sk);
982 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
983 u32 (*sndbuf_expand)(struct sock *sk);
984 /* call when packets are delivered to update cwnd and pacing rate,
985 * after all the ca_state processing. (optional)
986 */
987 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
988 /* get info for inet_diag (optional) */
989 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
990 union tcp_cc_info *info);
991
992 char name[TCP_CA_NAME_MAX];
993 struct module *owner;
994};
995
996int tcp_register_congestion_control(struct tcp_congestion_ops *type);
997void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
998
999void tcp_assign_congestion_control(struct sock *sk);
1000void tcp_init_congestion_control(struct sock *sk);
1001void tcp_cleanup_congestion_control(struct sock *sk);
1002int tcp_set_default_congestion_control(const char *name);
1003void tcp_get_default_congestion_control(char *name);
1004void tcp_get_available_congestion_control(char *buf, size_t len);
1005void tcp_get_allowed_congestion_control(char *buf, size_t len);
1006int tcp_set_allowed_congestion_control(char *allowed);
1007int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit);
1008u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1009void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1010
1011u32 tcp_reno_ssthresh(struct sock *sk);
1012u32 tcp_reno_undo_cwnd(struct sock *sk);
1013void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1014extern struct tcp_congestion_ops tcp_reno;
1015
1016struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1017u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
1018#ifdef CONFIG_INET
1019char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1020#else
1021static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1022{
1023 return NULL;
1024}
1025#endif
1026
1027static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1028{
1029 const struct inet_connection_sock *icsk = inet_csk(sk);
1030
1031 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1032}
1033
1034static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1035{
1036 struct inet_connection_sock *icsk = inet_csk(sk);
1037
1038 if (icsk->icsk_ca_ops->set_state)
1039 icsk->icsk_ca_ops->set_state(sk, ca_state);
1040 icsk->icsk_ca_state = ca_state;
1041}
1042
1043static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1044{
1045 const struct inet_connection_sock *icsk = inet_csk(sk);
1046
1047 if (icsk->icsk_ca_ops->cwnd_event)
1048 icsk->icsk_ca_ops->cwnd_event(sk, event);
1049}
1050
1051/* From tcp_rate.c */
1052void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1053void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1054 struct rate_sample *rs);
1055void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1056 struct rate_sample *rs);
1057void tcp_rate_check_app_limited(struct sock *sk);
1058
1059/* These functions determine how the current flow behaves in respect of SACK
1060 * handling. SACK is negotiated with the peer, and therefore it can vary
1061 * between different flows.
1062 *
1063 * tcp_is_sack - SACK enabled
1064 * tcp_is_reno - No SACK
1065 * tcp_is_fack - FACK enabled, implies SACK enabled
1066 */
1067static inline int tcp_is_sack(const struct tcp_sock *tp)
1068{
1069 return tp->rx_opt.sack_ok;
1070}
1071
1072static inline bool tcp_is_reno(const struct tcp_sock *tp)
1073{
1074 return !tcp_is_sack(tp);
1075}
1076
1077static inline bool tcp_is_fack(const struct tcp_sock *tp)
1078{
1079 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
1080}
1081
1082static inline void tcp_enable_fack(struct tcp_sock *tp)
1083{
1084 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
1085}
1086
1087static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1088{
1089 return tp->sacked_out + tp->lost_out;
1090}
1091
1092/* This determines how many packets are "in the network" to the best
1093 * of our knowledge. In many cases it is conservative, but where
1094 * detailed information is available from the receiver (via SACK
1095 * blocks etc.) we can make more aggressive calculations.
1096 *
1097 * Use this for decisions involving congestion control, use just
1098 * tp->packets_out to determine if the send queue is empty or not.
1099 *
1100 * Read this equation as:
1101 *
1102 * "Packets sent once on transmission queue" MINUS
1103 * "Packets left network, but not honestly ACKed yet" PLUS
1104 * "Packets fast retransmitted"
1105 */
1106static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1107{
1108 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1109}
1110
1111#define TCP_INFINITE_SSTHRESH 0x7fffffff
1112
1113static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1114{
1115 return tp->snd_cwnd < tp->snd_ssthresh;
1116}
1117
1118static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1119{
1120 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1121}
1122
1123static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1124{
1125 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1126 (1 << inet_csk(sk)->icsk_ca_state);
1127}
1128
1129/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1130 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1131 * ssthresh.
1132 */
1133static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1134{
1135 const struct tcp_sock *tp = tcp_sk(sk);
1136
1137 if (tcp_in_cwnd_reduction(sk))
1138 return tp->snd_ssthresh;
1139 else
1140 return max(tp->snd_ssthresh,
1141 ((tp->snd_cwnd >> 1) +
1142 (tp->snd_cwnd >> 2)));
1143}
1144
1145/* Use define here intentionally to get WARN_ON location shown at the caller */
1146#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1147
1148void tcp_enter_cwr(struct sock *sk);
1149__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1150
1151/* The maximum number of MSS of available cwnd for which TSO defers
1152 * sending if not using sysctl_tcp_tso_win_divisor.
1153 */
1154static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1155{
1156 return 3;
1157}
1158
1159/* Returns end sequence number of the receiver's advertised window */
1160static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1161{
1162 return tp->snd_una + tp->snd_wnd;
1163}
1164
1165/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1166 * flexible approach. The RFC suggests cwnd should not be raised unless
1167 * it was fully used previously. And that's exactly what we do in
1168 * congestion avoidance mode. But in slow start we allow cwnd to grow
1169 * as long as the application has used half the cwnd.
1170 * Example :
1171 * cwnd is 10 (IW10), but application sends 9 frames.
1172 * We allow cwnd to reach 18 when all frames are ACKed.
1173 * This check is safe because it's as aggressive as slow start which already
1174 * risks 100% overshoot. The advantage is that we discourage application to
1175 * either send more filler packets or data to artificially blow up the cwnd
1176 * usage, and allow application-limited process to probe bw more aggressively.
1177 */
1178static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1179{
1180 const struct tcp_sock *tp = tcp_sk(sk);
1181
1182 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1183 if (tcp_in_slow_start(tp))
1184 return tp->snd_cwnd < 2 * tp->max_packets_out;
1185
1186 return tp->is_cwnd_limited;
1187}
1188
1189/* Something is really bad, we could not queue an additional packet,
1190 * because qdisc is full or receiver sent a 0 window.
1191 * We do not want to add fuel to the fire, or abort too early,
1192 * so make sure the timer we arm now is at least 200ms in the future,
1193 * regardless of current icsk_rto value (as it could be ~2ms)
1194 */
1195static inline unsigned long tcp_probe0_base(const struct sock *sk)
1196{
1197 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1198}
1199
1200/* Variant of inet_csk_rto_backoff() used for zero window probes */
1201static inline unsigned long tcp_probe0_when(const struct sock *sk,
1202 unsigned long max_when)
1203{
1204 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1205
1206 return (unsigned long)min_t(u64, when, max_when);
1207}
1208
1209static inline void tcp_check_probe_timer(struct sock *sk)
1210{
1211 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1212 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1213 tcp_probe0_base(sk), TCP_RTO_MAX);
1214}
1215
1216static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1217{
1218 tp->snd_wl1 = seq;
1219}
1220
1221static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1222{
1223 tp->snd_wl1 = seq;
1224}
1225
1226/*
1227 * Calculate(/check) TCP checksum
1228 */
1229static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1230 __be32 daddr, __wsum base)
1231{
1232 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1233}
1234
1235static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1236{
1237 return __skb_checksum_complete(skb);
1238}
1239
1240static inline bool tcp_checksum_complete(struct sk_buff *skb)
1241{
1242 return !skb_csum_unnecessary(skb) &&
1243 __tcp_checksum_complete(skb);
1244}
1245
1246/* Prequeue for VJ style copy to user, combined with checksumming. */
1247
1248static inline void tcp_prequeue_init(struct tcp_sock *tp)
1249{
1250 tp->ucopy.task = NULL;
1251 tp->ucopy.len = 0;
1252 tp->ucopy.memory = 0;
1253 skb_queue_head_init(&tp->ucopy.prequeue);
1254}
1255
1256bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1257bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1258int tcp_filter(struct sock *sk, struct sk_buff *skb);
1259
1260#undef STATE_TRACE
1261
1262#ifdef STATE_TRACE
1263static const char *statename[]={
1264 "Unused","Established","Syn Sent","Syn Recv",
1265 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1266 "Close Wait","Last ACK","Listen","Closing"
1267};
1268#endif
1269void tcp_set_state(struct sock *sk, int state);
1270
1271void tcp_done(struct sock *sk);
1272
1273int tcp_abort(struct sock *sk, int err);
1274
1275static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1276{
1277 rx_opt->dsack = 0;
1278 rx_opt->num_sacks = 0;
1279}
1280
1281u32 tcp_default_init_rwnd(u32 mss);
1282void tcp_cwnd_restart(struct sock *sk, s32 delta);
1283
1284static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1285{
1286 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1287 struct tcp_sock *tp = tcp_sk(sk);
1288 s32 delta;
1289
1290 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1291 ca_ops->cong_control)
1292 return;
1293 delta = tcp_jiffies32 - tp->lsndtime;
1294 if (delta > inet_csk(sk)->icsk_rto)
1295 tcp_cwnd_restart(sk, delta);
1296}
1297
1298/* Determine a window scaling and initial window to offer. */
1299void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1300 __u32 *window_clamp, int wscale_ok,
1301 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1302
1303static inline int tcp_win_from_space(int space)
1304{
1305 int tcp_adv_win_scale = sysctl_tcp_adv_win_scale;
1306
1307 return tcp_adv_win_scale <= 0 ?
1308 (space>>(-tcp_adv_win_scale)) :
1309 space - (space>>tcp_adv_win_scale);
1310}
1311
1312/* Note: caller must be prepared to deal with negative returns */
1313static inline int tcp_space(const struct sock *sk)
1314{
1315 return tcp_win_from_space(sk->sk_rcvbuf -
1316 atomic_read(&sk->sk_rmem_alloc));
1317}
1318
1319static inline int tcp_full_space(const struct sock *sk)
1320{
1321 return tcp_win_from_space(sk->sk_rcvbuf);
1322}
1323
1324extern void tcp_openreq_init_rwin(struct request_sock *req,
1325 const struct sock *sk_listener,
1326 const struct dst_entry *dst);
1327
1328void tcp_enter_memory_pressure(struct sock *sk);
1329void tcp_leave_memory_pressure(struct sock *sk);
1330
1331static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1332{
1333 struct net *net = sock_net((struct sock *)tp);
1334
1335 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1336}
1337
1338static inline int keepalive_time_when(const struct tcp_sock *tp)
1339{
1340 struct net *net = sock_net((struct sock *)tp);
1341
1342 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1343}
1344
1345static inline int keepalive_probes(const struct tcp_sock *tp)
1346{
1347 struct net *net = sock_net((struct sock *)tp);
1348
1349 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1350}
1351
1352static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1353{
1354 const struct inet_connection_sock *icsk = &tp->inet_conn;
1355
1356 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1357 tcp_jiffies32 - tp->rcv_tstamp);
1358}
1359
1360static inline int tcp_fin_time(const struct sock *sk)
1361{
1362 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1363 const int rto = inet_csk(sk)->icsk_rto;
1364
1365 if (fin_timeout < (rto << 2) - (rto >> 1))
1366 fin_timeout = (rto << 2) - (rto >> 1);
1367
1368 return fin_timeout;
1369}
1370
1371static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1372 int paws_win)
1373{
1374 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1375 return true;
1376 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1377 return true;
1378 /*
1379 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1380 * then following tcp messages have valid values. Ignore 0 value,
1381 * or else 'negative' tsval might forbid us to accept their packets.
1382 */
1383 if (!rx_opt->ts_recent)
1384 return true;
1385 return false;
1386}
1387
1388static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1389 int rst)
1390{
1391 if (tcp_paws_check(rx_opt, 0))
1392 return false;
1393
1394 /* RST segments are not recommended to carry timestamp,
1395 and, if they do, it is recommended to ignore PAWS because
1396 "their cleanup function should take precedence over timestamps."
1397 Certainly, it is mistake. It is necessary to understand the reasons
1398 of this constraint to relax it: if peer reboots, clock may go
1399 out-of-sync and half-open connections will not be reset.
1400 Actually, the problem would be not existing if all
1401 the implementations followed draft about maintaining clock
1402 via reboots. Linux-2.2 DOES NOT!
1403
1404 However, we can relax time bounds for RST segments to MSL.
1405 */
1406 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1407 return false;
1408 return true;
1409}
1410
1411bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1412 int mib_idx, u32 *last_oow_ack_time);
1413
1414static inline void tcp_mib_init(struct net *net)
1415{
1416 /* See RFC 2012 */
1417 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1418 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1419 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1420 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1421}
1422
1423/* from STCP */
1424static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1425{
1426 tp->lost_skb_hint = NULL;
1427}
1428
1429static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1430{
1431 tcp_clear_retrans_hints_partial(tp);
1432 tp->retransmit_skb_hint = NULL;
1433}
1434
1435union tcp_md5_addr {
1436 struct in_addr a4;
1437#if IS_ENABLED(CONFIG_IPV6)
1438 struct in6_addr a6;
1439#endif
1440};
1441
1442/* - key database */
1443struct tcp_md5sig_key {
1444 struct hlist_node node;
1445 u8 keylen;
1446 u8 family; /* AF_INET or AF_INET6 */
1447 union tcp_md5_addr addr;
1448 u8 prefixlen;
1449 u8 key[TCP_MD5SIG_MAXKEYLEN];
1450 struct rcu_head rcu;
1451};
1452
1453/* - sock block */
1454struct tcp_md5sig_info {
1455 struct hlist_head head;
1456 struct rcu_head rcu;
1457};
1458
1459/* - pseudo header */
1460struct tcp4_pseudohdr {
1461 __be32 saddr;
1462 __be32 daddr;
1463 __u8 pad;
1464 __u8 protocol;
1465 __be16 len;
1466};
1467
1468struct tcp6_pseudohdr {
1469 struct in6_addr saddr;
1470 struct in6_addr daddr;
1471 __be32 len;
1472 __be32 protocol; /* including padding */
1473};
1474
1475union tcp_md5sum_block {
1476 struct tcp4_pseudohdr ip4;
1477#if IS_ENABLED(CONFIG_IPV6)
1478 struct tcp6_pseudohdr ip6;
1479#endif
1480};
1481
1482/* - pool: digest algorithm, hash description and scratch buffer */
1483struct tcp_md5sig_pool {
1484 struct ahash_request *md5_req;
1485 void *scratch;
1486};
1487
1488/* - functions */
1489int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1490 const struct sock *sk, const struct sk_buff *skb);
1491int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1492 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
1493 gfp_t gfp);
1494int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1495 int family, u8 prefixlen);
1496struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1497 const struct sock *addr_sk);
1498
1499#ifdef CONFIG_TCP_MD5SIG
1500struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1501 const union tcp_md5_addr *addr,
1502 int family);
1503#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1504#else
1505static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1506 const union tcp_md5_addr *addr,
1507 int family)
1508{
1509 return NULL;
1510}
1511#define tcp_twsk_md5_key(twsk) NULL
1512#endif
1513
1514bool tcp_alloc_md5sig_pool(void);
1515
1516struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1517static inline void tcp_put_md5sig_pool(void)
1518{
1519 local_bh_enable();
1520}
1521
1522int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1523 unsigned int header_len);
1524int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1525 const struct tcp_md5sig_key *key);
1526
1527/* From tcp_fastopen.c */
1528void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1529 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1530 unsigned long *last_syn_loss);
1531void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1532 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1533 u16 try_exp);
1534struct tcp_fastopen_request {
1535 /* Fast Open cookie. Size 0 means a cookie request */
1536 struct tcp_fastopen_cookie cookie;
1537 struct msghdr *data; /* data in MSG_FASTOPEN */
1538 size_t size;
1539 int copied; /* queued in tcp_connect() */
1540};
1541void tcp_free_fastopen_req(struct tcp_sock *tp);
1542
1543extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1544int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1545void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1546struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1547 struct request_sock *req,
1548 struct tcp_fastopen_cookie *foc,
1549 struct dst_entry *dst);
1550void tcp_fastopen_init_key_once(bool publish);
1551bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1552 struct tcp_fastopen_cookie *cookie);
1553bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1554#define TCP_FASTOPEN_KEY_LENGTH 16
1555
1556/* Fastopen key context */
1557struct tcp_fastopen_context {
1558 struct crypto_cipher *tfm;
1559 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1560 struct rcu_head rcu;
1561};
1562
1563extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1564void tcp_fastopen_active_disable(struct sock *sk);
1565bool tcp_fastopen_active_should_disable(struct sock *sk);
1566void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1567void tcp_fastopen_active_timeout_reset(void);
1568
1569/* Latencies incurred by various limits for a sender. They are
1570 * chronograph-like stats that are mutually exclusive.
1571 */
1572enum tcp_chrono {
1573 TCP_CHRONO_UNSPEC,
1574 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1575 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1576 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1577 __TCP_CHRONO_MAX,
1578};
1579
1580void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1581void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1582
1583/* write queue abstraction */
1584static inline void tcp_write_queue_purge(struct sock *sk)
1585{
1586 struct sk_buff *skb;
1587
1588 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1589 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1590 sk_wmem_free_skb(sk, skb);
1591 sk_mem_reclaim(sk);
1592 tcp_clear_all_retrans_hints(tcp_sk(sk));
1593}
1594
1595static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1596{
1597 return skb_peek(&sk->sk_write_queue);
1598}
1599
1600static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1601{
1602 return skb_peek_tail(&sk->sk_write_queue);
1603}
1604
1605static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1606 const struct sk_buff *skb)
1607{
1608 return skb_queue_next(&sk->sk_write_queue, skb);
1609}
1610
1611static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1612 const struct sk_buff *skb)
1613{
1614 return skb_queue_prev(&sk->sk_write_queue, skb);
1615}
1616
1617#define tcp_for_write_queue(skb, sk) \
1618 skb_queue_walk(&(sk)->sk_write_queue, skb)
1619
1620#define tcp_for_write_queue_from(skb, sk) \
1621 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1622
1623#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1624 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1625
1626static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1627{
1628 return sk->sk_send_head;
1629}
1630
1631static inline bool tcp_skb_is_last(const struct sock *sk,
1632 const struct sk_buff *skb)
1633{
1634 return skb_queue_is_last(&sk->sk_write_queue, skb);
1635}
1636
1637static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1638{
1639 if (tcp_skb_is_last(sk, skb))
1640 sk->sk_send_head = NULL;
1641 else
1642 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1643}
1644
1645static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1646{
1647 if (sk->sk_send_head == skb_unlinked) {
1648 sk->sk_send_head = NULL;
1649 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1650 }
1651 if (tcp_sk(sk)->highest_sack == skb_unlinked)
1652 tcp_sk(sk)->highest_sack = NULL;
1653}
1654
1655static inline void tcp_init_send_head(struct sock *sk)
1656{
1657 sk->sk_send_head = NULL;
1658}
1659
1660static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1661{
1662 __skb_queue_tail(&sk->sk_write_queue, skb);
1663}
1664
1665static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1666{
1667 __tcp_add_write_queue_tail(sk, skb);
1668
1669 /* Queue it, remembering where we must start sending. */
1670 if (sk->sk_send_head == NULL) {
1671 sk->sk_send_head = skb;
1672 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1673
1674 if (tcp_sk(sk)->highest_sack == NULL)
1675 tcp_sk(sk)->highest_sack = skb;
1676 }
1677}
1678
1679static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1680{
1681 __skb_queue_head(&sk->sk_write_queue, skb);
1682}
1683
1684/* Insert buff after skb on the write queue of sk. */
1685static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1686 struct sk_buff *buff,
1687 struct sock *sk)
1688{
1689 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1690}
1691
1692/* Insert new before skb on the write queue of sk. */
1693static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1694 struct sk_buff *skb,
1695 struct sock *sk)
1696{
1697 __skb_queue_before(&sk->sk_write_queue, skb, new);
1698
1699 if (sk->sk_send_head == skb)
1700 sk->sk_send_head = new;
1701}
1702
1703static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1704{
1705 __skb_unlink(skb, &sk->sk_write_queue);
1706}
1707
1708static inline bool tcp_write_queue_empty(struct sock *sk)
1709{
1710 return skb_queue_empty(&sk->sk_write_queue);
1711}
1712
1713static inline void tcp_push_pending_frames(struct sock *sk)
1714{
1715 if (tcp_send_head(sk)) {
1716 struct tcp_sock *tp = tcp_sk(sk);
1717
1718 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1719 }
1720}
1721
1722/* Start sequence of the skb just after the highest skb with SACKed
1723 * bit, valid only if sacked_out > 0 or when the caller has ensured
1724 * validity by itself.
1725 */
1726static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1727{
1728 if (!tp->sacked_out)
1729 return tp->snd_una;
1730
1731 if (tp->highest_sack == NULL)
1732 return tp->snd_nxt;
1733
1734 return TCP_SKB_CB(tp->highest_sack)->seq;
1735}
1736
1737static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1738{
1739 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1740 tcp_write_queue_next(sk, skb);
1741}
1742
1743static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1744{
1745 return tcp_sk(sk)->highest_sack;
1746}
1747
1748static inline void tcp_highest_sack_reset(struct sock *sk)
1749{
1750 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1751}
1752
1753/* Called when old skb is about to be deleted and replaced by new skb */
1754static inline void tcp_highest_sack_replace(struct sock *sk,
1755 struct sk_buff *old,
1756 struct sk_buff *new)
1757{
1758 if (old == tcp_highest_sack(sk))
1759 tcp_sk(sk)->highest_sack = new;
1760}
1761
1762/* This helper checks if socket has IP_TRANSPARENT set */
1763static inline bool inet_sk_transparent(const struct sock *sk)
1764{
1765 switch (sk->sk_state) {
1766 case TCP_TIME_WAIT:
1767 return inet_twsk(sk)->tw_transparent;
1768 case TCP_NEW_SYN_RECV:
1769 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1770 }
1771 return inet_sk(sk)->transparent;
1772}
1773
1774/* Determines whether this is a thin stream (which may suffer from
1775 * increased latency). Used to trigger latency-reducing mechanisms.
1776 */
1777static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1778{
1779 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1780}
1781
1782/* /proc */
1783enum tcp_seq_states {
1784 TCP_SEQ_STATE_LISTENING,
1785 TCP_SEQ_STATE_ESTABLISHED,
1786};
1787
1788int tcp_seq_open(struct inode *inode, struct file *file);
1789
1790struct tcp_seq_afinfo {
1791 char *name;
1792 sa_family_t family;
1793 const struct file_operations *seq_fops;
1794 struct seq_operations seq_ops;
1795};
1796
1797struct tcp_iter_state {
1798 struct seq_net_private p;
1799 sa_family_t family;
1800 enum tcp_seq_states state;
1801 struct sock *syn_wait_sk;
1802 int bucket, offset, sbucket, num;
1803 loff_t last_pos;
1804};
1805
1806int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1807void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1808
1809extern struct request_sock_ops tcp_request_sock_ops;
1810extern struct request_sock_ops tcp6_request_sock_ops;
1811
1812void tcp_v4_destroy_sock(struct sock *sk);
1813
1814struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1815 netdev_features_t features);
1816struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1817int tcp_gro_complete(struct sk_buff *skb);
1818
1819void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1820
1821static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1822{
1823 struct net *net = sock_net((struct sock *)tp);
1824 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1825}
1826
1827static inline bool tcp_stream_memory_free(const struct sock *sk)
1828{
1829 const struct tcp_sock *tp = tcp_sk(sk);
1830 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1831
1832 return notsent_bytes < tcp_notsent_lowat(tp);
1833}
1834
1835#ifdef CONFIG_PROC_FS
1836int tcp4_proc_init(void);
1837void tcp4_proc_exit(void);
1838#endif
1839
1840int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1841int tcp_conn_request(struct request_sock_ops *rsk_ops,
1842 const struct tcp_request_sock_ops *af_ops,
1843 struct sock *sk, struct sk_buff *skb);
1844
1845/* TCP af-specific functions */
1846struct tcp_sock_af_ops {
1847#ifdef CONFIG_TCP_MD5SIG
1848 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1849 const struct sock *addr_sk);
1850 int (*calc_md5_hash)(char *location,
1851 const struct tcp_md5sig_key *md5,
1852 const struct sock *sk,
1853 const struct sk_buff *skb);
1854 int (*md5_parse)(struct sock *sk,
1855 int optname,
1856 char __user *optval,
1857 int optlen);
1858#endif
1859};
1860
1861struct tcp_request_sock_ops {
1862 u16 mss_clamp;
1863#ifdef CONFIG_TCP_MD5SIG
1864 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1865 const struct sock *addr_sk);
1866 int (*calc_md5_hash) (char *location,
1867 const struct tcp_md5sig_key *md5,
1868 const struct sock *sk,
1869 const struct sk_buff *skb);
1870#endif
1871 void (*init_req)(struct request_sock *req,
1872 const struct sock *sk_listener,
1873 struct sk_buff *skb);
1874#ifdef CONFIG_SYN_COOKIES
1875 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1876 __u16 *mss);
1877#endif
1878 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1879 const struct request_sock *req);
1880 u32 (*init_seq)(const struct sk_buff *skb);
1881 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1882 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1883 struct flowi *fl, struct request_sock *req,
1884 struct tcp_fastopen_cookie *foc,
1885 enum tcp_synack_type synack_type);
1886};
1887
1888#ifdef CONFIG_SYN_COOKIES
1889static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1890 const struct sock *sk, struct sk_buff *skb,
1891 __u16 *mss)
1892{
1893 tcp_synq_overflow(sk);
1894 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1895 return ops->cookie_init_seq(skb, mss);
1896}
1897#else
1898static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1899 const struct sock *sk, struct sk_buff *skb,
1900 __u16 *mss)
1901{
1902 return 0;
1903}
1904#endif
1905
1906int tcpv4_offload_init(void);
1907
1908void tcp_v4_init(void);
1909void tcp_init(void);
1910
1911/* tcp_recovery.c */
1912extern void tcp_rack_mark_lost(struct sock *sk);
1913extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
1914 u64 xmit_time);
1915extern void tcp_rack_reo_timeout(struct sock *sk);
1916
1917/* At how many usecs into the future should the RTO fire? */
1918static inline s64 tcp_rto_delta_us(const struct sock *sk)
1919{
1920 const struct sk_buff *skb = tcp_write_queue_head(sk);
1921 u32 rto = inet_csk(sk)->icsk_rto;
1922 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto);
1923
1924 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
1925}
1926
1927/*
1928 * Save and compile IPv4 options, return a pointer to it
1929 */
1930static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
1931{
1932 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1933 struct ip_options_rcu *dopt = NULL;
1934
1935 if (opt->optlen) {
1936 int opt_size = sizeof(*dopt) + opt->optlen;
1937
1938 dopt = kmalloc(opt_size, GFP_ATOMIC);
1939 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
1940 kfree(dopt);
1941 dopt = NULL;
1942 }
1943 }
1944 return dopt;
1945}
1946
1947/* locally generated TCP pure ACKs have skb->truesize == 2
1948 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1949 * This is much faster than dissecting the packet to find out.
1950 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1951 */
1952static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1953{
1954 return skb->truesize == 2;
1955}
1956
1957static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1958{
1959 skb->truesize = 2;
1960}
1961
1962static inline int tcp_inq(struct sock *sk)
1963{
1964 struct tcp_sock *tp = tcp_sk(sk);
1965 int answ;
1966
1967 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1968 answ = 0;
1969 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1970 !tp->urg_data ||
1971 before(tp->urg_seq, tp->copied_seq) ||
1972 !before(tp->urg_seq, tp->rcv_nxt)) {
1973
1974 answ = tp->rcv_nxt - tp->copied_seq;
1975
1976 /* Subtract 1, if FIN was received */
1977 if (answ && sock_flag(sk, SOCK_DONE))
1978 answ--;
1979 } else {
1980 answ = tp->urg_seq - tp->copied_seq;
1981 }
1982
1983 return answ;
1984}
1985
1986int tcp_peek_len(struct socket *sock);
1987
1988static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1989{
1990 u16 segs_in;
1991
1992 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1993 tp->segs_in += segs_in;
1994 if (skb->len > tcp_hdrlen(skb))
1995 tp->data_segs_in += segs_in;
1996}
1997
1998/*
1999 * TCP listen path runs lockless.
2000 * We forced "struct sock" to be const qualified to make sure
2001 * we don't modify one of its field by mistake.
2002 * Here, we increment sk_drops which is an atomic_t, so we can safely
2003 * make sock writable again.
2004 */
2005static inline void tcp_listendrop(const struct sock *sk)
2006{
2007 atomic_inc(&((struct sock *)sk)->sk_drops);
2008 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2009}
2010
2011enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2012
2013/*
2014 * Interface for adding Upper Level Protocols over TCP
2015 */
2016
2017#define TCP_ULP_NAME_MAX 16
2018#define TCP_ULP_MAX 128
2019#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2020
2021struct tcp_ulp_ops {
2022 struct list_head list;
2023
2024 /* initialize ulp */
2025 int (*init)(struct sock *sk);
2026 /* cleanup ulp */
2027 void (*release)(struct sock *sk);
2028
2029 char name[TCP_ULP_NAME_MAX];
2030 struct module *owner;
2031};
2032int tcp_register_ulp(struct tcp_ulp_ops *type);
2033void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2034int tcp_set_ulp(struct sock *sk, const char *name);
2035void tcp_get_available_ulp(char *buf, size_t len);
2036void tcp_cleanup_ulp(struct sock *sk);
2037
2038/* Call BPF_SOCK_OPS program that returns an int. If the return value
2039 * is < 0, then the BPF op failed (for example if the loaded BPF
2040 * program does not support the chosen operation or there is no BPF
2041 * program loaded).
2042 */
2043#ifdef CONFIG_BPF
2044static inline int tcp_call_bpf(struct sock *sk, int op)
2045{
2046 struct bpf_sock_ops_kern sock_ops;
2047 int ret;
2048
2049 if (sk_fullsock(sk))
2050 sock_owned_by_me(sk);
2051
2052 memset(&sock_ops, 0, sizeof(sock_ops));
2053 sock_ops.sk = sk;
2054 sock_ops.op = op;
2055
2056 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2057 if (ret == 0)
2058 ret = sock_ops.reply;
2059 else
2060 ret = -1;
2061 return ret;
2062}
2063#else
2064static inline int tcp_call_bpf(struct sock *sk, int op)
2065{
2066 return -EPERM;
2067}
2068#endif
2069
2070static inline u32 tcp_timeout_init(struct sock *sk)
2071{
2072 int timeout;
2073
2074 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT);
2075
2076 if (timeout <= 0)
2077 timeout = TCP_TIMEOUT_INIT;
2078 return timeout;
2079}
2080
2081static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2082{
2083 int rwnd;
2084
2085 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT);
2086
2087 if (rwnd < 0)
2088 rwnd = 0;
2089 return rwnd;
2090}
2091
2092static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2093{
2094 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1);
2095}
2096#endif /* _TCP_H */
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