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_reuseport.h>
40#include <net/sock.h>
41#include <net/snmp.h>
42#include <net/ip.h>
43#include <net/tcp_states.h>
44#include <net/inet_ecn.h>
45#include <net/dst.h>
46
47#include <linux/seq_file.h>
48#include <linux/memcontrol.h>
49#include <linux/bpf-cgroup.h>
50
51extern struct inet_hashinfo tcp_hashinfo;
52
53extern struct percpu_counter tcp_orphan_count;
54void tcp_time_wait(struct sock *sk, int state, int timeo);
55
56#define MAX_TCP_HEADER (128 + MAX_HEADER)
57#define MAX_TCP_OPTION_SPACE 40
58
59/*
60 * Never offer a window over 32767 without using window scaling. Some
61 * poor stacks do signed 16bit maths!
62 */
63#define MAX_TCP_WINDOW 32767U
64
65/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
66#define TCP_MIN_MSS 88U
67
68/* The least MTU to use for probing */
69#define TCP_BASE_MSS 1024
70
71/* probing interval, default to 10 minutes as per RFC4821 */
72#define TCP_PROBE_INTERVAL 600
73
74/* Specify interval when tcp mtu probing will stop */
75#define TCP_PROBE_THRESHOLD 8
76
77/* After receiving this amount of duplicate ACKs fast retransmit starts. */
78#define TCP_FASTRETRANS_THRESH 3
79
80/* Maximal number of ACKs sent quickly to accelerate slow-start. */
81#define TCP_MAX_QUICKACKS 16U
82
83/* Maximal number of window scale according to RFC1323 */
84#define TCP_MAX_WSCALE 14U
85
86/* urg_data states */
87#define TCP_URG_VALID 0x0100
88#define TCP_URG_NOTYET 0x0200
89#define TCP_URG_READ 0x0400
90
91#define TCP_RETR1 3 /*
92 * This is how many retries it does before it
93 * tries to figure out if the gateway is
94 * down. Minimal RFC value is 3; it corresponds
95 * to ~3sec-8min depending on RTO.
96 */
97
98#define TCP_RETR2 15 /*
99 * This should take at least
100 * 90 minutes to time out.
101 * RFC1122 says that the limit is 100 sec.
102 * 15 is ~13-30min depending on RTO.
103 */
104
105#define TCP_SYN_RETRIES 6 /* This is how many retries are done
106 * when active opening a connection.
107 * RFC1122 says the minimum retry MUST
108 * be at least 180secs. Nevertheless
109 * this value is corresponding to
110 * 63secs of retransmission with the
111 * current initial RTO.
112 */
113
114#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
115 * when passive opening a connection.
116 * This is corresponding to 31secs of
117 * retransmission with the current
118 * initial RTO.
119 */
120
121#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
122 * state, about 60 seconds */
123#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
124 /* BSD style FIN_WAIT2 deadlock breaker.
125 * It used to be 3min, new value is 60sec,
126 * to combine FIN-WAIT-2 timeout with
127 * TIME-WAIT timer.
128 */
129
130#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
131#if HZ >= 100
132#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
133#define TCP_ATO_MIN ((unsigned)(HZ/25))
134#else
135#define TCP_DELACK_MIN 4U
136#define TCP_ATO_MIN 4U
137#endif
138#define TCP_RTO_MAX ((unsigned)(120*HZ))
139#define TCP_RTO_MIN ((unsigned)(HZ/5))
140#define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
141#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
142#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
143 * used as a fallback RTO for the
144 * initial data transmission if no
145 * valid RTT sample has been acquired,
146 * most likely due to retrans in 3WHS.
147 */
148
149#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
150 * for local resources.
151 */
152#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
153#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
154#define TCP_KEEPALIVE_INTVL (75*HZ)
155
156#define MAX_TCP_KEEPIDLE 32767
157#define MAX_TCP_KEEPINTVL 32767
158#define MAX_TCP_KEEPCNT 127
159#define MAX_TCP_SYNCNT 127
160
161#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
162
163#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
164#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
165 * after this time. It should be equal
166 * (or greater than) TCP_TIMEWAIT_LEN
167 * to provide reliability equal to one
168 * provided by timewait state.
169 */
170#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
171 * timestamps. It must be less than
172 * minimal timewait lifetime.
173 */
174/*
175 * TCP option
176 */
177
178#define TCPOPT_NOP 1 /* Padding */
179#define TCPOPT_EOL 0 /* End of options */
180#define TCPOPT_MSS 2 /* Segment size negotiating */
181#define TCPOPT_WINDOW 3 /* Window scaling */
182#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
183#define TCPOPT_SACK 5 /* SACK Block */
184#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
185#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
186#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
187#define TCPOPT_EXP 254 /* Experimental */
188/* Magic number to be after the option value for sharing TCP
189 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
190 */
191#define TCPOPT_FASTOPEN_MAGIC 0xF989
192#define TCPOPT_SMC_MAGIC 0xE2D4C3D9
193
194/*
195 * TCP option lengths
196 */
197
198#define TCPOLEN_MSS 4
199#define TCPOLEN_WINDOW 3
200#define TCPOLEN_SACK_PERM 2
201#define TCPOLEN_TIMESTAMP 10
202#define TCPOLEN_MD5SIG 18
203#define TCPOLEN_FASTOPEN_BASE 2
204#define TCPOLEN_EXP_FASTOPEN_BASE 4
205#define TCPOLEN_EXP_SMC_BASE 6
206
207/* But this is what stacks really send out. */
208#define TCPOLEN_TSTAMP_ALIGNED 12
209#define TCPOLEN_WSCALE_ALIGNED 4
210#define TCPOLEN_SACKPERM_ALIGNED 4
211#define TCPOLEN_SACK_BASE 2
212#define TCPOLEN_SACK_BASE_ALIGNED 4
213#define TCPOLEN_SACK_PERBLOCK 8
214#define TCPOLEN_MD5SIG_ALIGNED 20
215#define TCPOLEN_MSS_ALIGNED 4
216#define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
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_max_orphans;
245extern long sysctl_tcp_mem[3];
246
247#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
248#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
249#define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
250
251extern atomic_long_t tcp_memory_allocated;
252extern struct percpu_counter tcp_sockets_allocated;
253extern unsigned long tcp_memory_pressure;
254
255/* optimized version of sk_under_memory_pressure() for TCP sockets */
256static inline bool tcp_under_memory_pressure(const struct sock *sk)
257{
258 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
259 mem_cgroup_under_socket_pressure(sk->sk_memcg))
260 return true;
261
262 return tcp_memory_pressure;
263}
264/*
265 * The next routines deal with comparing 32 bit unsigned ints
266 * and worry about wraparound (automatic with unsigned arithmetic).
267 */
268
269static inline bool before(__u32 seq1, __u32 seq2)
270{
271 return (__s32)(seq1-seq2) < 0;
272}
273#define after(seq2, seq1) before(seq1, seq2)
274
275/* is s2<=s1<=s3 ? */
276static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
277{
278 return seq3 - seq2 >= seq1 - seq2;
279}
280
281static inline bool tcp_out_of_memory(struct sock *sk)
282{
283 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
284 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
285 return true;
286 return false;
287}
288
289void sk_forced_mem_schedule(struct sock *sk, int size);
290
291static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
292{
293 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
294 int orphans = percpu_counter_read_positive(ocp);
295
296 if (orphans << shift > sysctl_tcp_max_orphans) {
297 orphans = percpu_counter_sum_positive(ocp);
298 if (orphans << shift > sysctl_tcp_max_orphans)
299 return true;
300 }
301 return false;
302}
303
304bool tcp_check_oom(struct sock *sk, int shift);
305
306
307extern struct proto tcp_prot;
308
309#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
311#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
312#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
313
314void tcp_tasklet_init(void);
315
316void tcp_v4_err(struct sk_buff *skb, u32);
317
318void tcp_shutdown(struct sock *sk, int how);
319
320int tcp_v4_early_demux(struct sk_buff *skb);
321int tcp_v4_rcv(struct sk_buff *skb);
322
323int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
324int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
325int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
326int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
327 int flags);
328int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
329 size_t size, int flags);
330ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
331 size_t size, int flags);
332void tcp_release_cb(struct sock *sk);
333void tcp_wfree(struct sk_buff *skb);
334void tcp_write_timer_handler(struct sock *sk);
335void tcp_delack_timer_handler(struct sock *sk);
336int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
337int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
338void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
339void tcp_rcv_space_adjust(struct sock *sk);
340int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
341void tcp_twsk_destructor(struct sock *sk);
342ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
343 struct pipe_inode_info *pipe, size_t len,
344 unsigned int flags);
345
346void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
347static inline void tcp_dec_quickack_mode(struct sock *sk,
348 const unsigned int pkts)
349{
350 struct inet_connection_sock *icsk = inet_csk(sk);
351
352 if (icsk->icsk_ack.quick) {
353 if (pkts >= icsk->icsk_ack.quick) {
354 icsk->icsk_ack.quick = 0;
355 /* Leaving quickack mode we deflate ATO. */
356 icsk->icsk_ack.ato = TCP_ATO_MIN;
357 } else
358 icsk->icsk_ack.quick -= pkts;
359 }
360}
361
362#define TCP_ECN_OK 1
363#define TCP_ECN_QUEUE_CWR 2
364#define TCP_ECN_DEMAND_CWR 4
365#define TCP_ECN_SEEN 8
366
367enum tcp_tw_status {
368 TCP_TW_SUCCESS = 0,
369 TCP_TW_RST = 1,
370 TCP_TW_ACK = 2,
371 TCP_TW_SYN = 3
372};
373
374
375enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
376 struct sk_buff *skb,
377 const struct tcphdr *th);
378struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
379 struct request_sock *req, bool fastopen,
380 bool *lost_race);
381int tcp_child_process(struct sock *parent, struct sock *child,
382 struct sk_buff *skb);
383void tcp_enter_loss(struct sock *sk);
384void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
385void tcp_clear_retrans(struct tcp_sock *tp);
386void tcp_update_metrics(struct sock *sk);
387void tcp_init_metrics(struct sock *sk);
388void tcp_metrics_init(void);
389bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
390void tcp_close(struct sock *sk, long timeout);
391void tcp_init_sock(struct sock *sk);
392void tcp_init_transfer(struct sock *sk, int bpf_op);
393__poll_t tcp_poll(struct file *file, struct socket *sock,
394 struct poll_table_struct *wait);
395int tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397int tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
400 char __user *optval, int __user *optlen);
401int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
402 char __user *optval, unsigned int optlen);
403void tcp_set_keepalive(struct sock *sk, int val);
404void tcp_syn_ack_timeout(const struct request_sock *req);
405int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
406 int flags, int *addr_len);
407int tcp_set_rcvlowat(struct sock *sk, int val);
408void tcp_data_ready(struct sock *sk);
409int tcp_mmap(struct file *file, struct socket *sock,
410 struct vm_area_struct *vma);
411void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
412 struct tcp_options_received *opt_rx,
413 int estab, struct tcp_fastopen_cookie *foc);
414const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
415
416/*
417 * TCP v4 functions exported for the inet6 API
418 */
419
420void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
421void tcp_v4_mtu_reduced(struct sock *sk);
422void tcp_req_err(struct sock *sk, u32 seq, bool abort);
423int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
424struct sock *tcp_create_openreq_child(const struct sock *sk,
425 struct request_sock *req,
426 struct sk_buff *skb);
427void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
428struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
429 struct request_sock *req,
430 struct dst_entry *dst,
431 struct request_sock *req_unhash,
432 bool *own_req);
433int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
434int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
435int tcp_connect(struct sock *sk);
436enum tcp_synack_type {
437 TCP_SYNACK_NORMAL,
438 TCP_SYNACK_FASTOPEN,
439 TCP_SYNACK_COOKIE,
440};
441struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
442 struct request_sock *req,
443 struct tcp_fastopen_cookie *foc,
444 enum tcp_synack_type synack_type);
445int tcp_disconnect(struct sock *sk, int flags);
446
447void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
448int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
449void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
450
451/* From syncookies.c */
452struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
453 struct request_sock *req,
454 struct dst_entry *dst, u32 tsoff);
455int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
456 u32 cookie);
457struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
458#ifdef CONFIG_SYN_COOKIES
459
460/* Syncookies use a monotonic timer which increments every 60 seconds.
461 * This counter is used both as a hash input and partially encoded into
462 * the cookie value. A cookie is only validated further if the delta
463 * between the current counter value and the encoded one is less than this,
464 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
465 * the counter advances immediately after a cookie is generated).
466 */
467#define MAX_SYNCOOKIE_AGE 2
468#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
469#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
470
471/* syncookies: remember time of last synqueue overflow
472 * But do not dirty this field too often (once per second is enough)
473 * It is racy as we do not hold a lock, but race is very minor.
474 */
475static inline void tcp_synq_overflow(const struct sock *sk)
476{
477 unsigned int last_overflow;
478 unsigned int now = jiffies;
479
480 if (sk->sk_reuseport) {
481 struct sock_reuseport *reuse;
482
483 reuse = rcu_dereference(sk->sk_reuseport_cb);
484 if (likely(reuse)) {
485 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
486 if (time_after32(now, last_overflow + HZ))
487 WRITE_ONCE(reuse->synq_overflow_ts, now);
488 return;
489 }
490 }
491
492 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
493 if (time_after32(now, last_overflow + HZ))
494 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
495}
496
497/* syncookies: no recent synqueue overflow on this listening socket? */
498static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
499{
500 unsigned int last_overflow;
501 unsigned int now = jiffies;
502
503 if (sk->sk_reuseport) {
504 struct sock_reuseport *reuse;
505
506 reuse = rcu_dereference(sk->sk_reuseport_cb);
507 if (likely(reuse)) {
508 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
509 return time_after32(now, last_overflow +
510 TCP_SYNCOOKIE_VALID);
511 }
512 }
513
514 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
515 return time_after32(now, last_overflow + TCP_SYNCOOKIE_VALID);
516}
517
518static inline u32 tcp_cookie_time(void)
519{
520 u64 val = get_jiffies_64();
521
522 do_div(val, TCP_SYNCOOKIE_PERIOD);
523 return val;
524}
525
526u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
527 u16 *mssp);
528__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
529u64 cookie_init_timestamp(struct request_sock *req);
530bool cookie_timestamp_decode(const struct net *net,
531 struct tcp_options_received *opt);
532bool cookie_ecn_ok(const struct tcp_options_received *opt,
533 const struct net *net, const struct dst_entry *dst);
534
535/* From net/ipv6/syncookies.c */
536int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
537 u32 cookie);
538struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
539
540u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
541 const struct tcphdr *th, u16 *mssp);
542__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
543#endif
544/* tcp_output.c */
545
546void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
547 int nonagle);
548int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
549int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
550void tcp_retransmit_timer(struct sock *sk);
551void tcp_xmit_retransmit_queue(struct sock *);
552void tcp_simple_retransmit(struct sock *);
553void tcp_enter_recovery(struct sock *sk, bool ece_ack);
554int tcp_trim_head(struct sock *, struct sk_buff *, u32);
555enum tcp_queue {
556 TCP_FRAG_IN_WRITE_QUEUE,
557 TCP_FRAG_IN_RTX_QUEUE,
558};
559int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
560 struct sk_buff *skb, u32 len,
561 unsigned int mss_now, gfp_t gfp);
562
563void tcp_send_probe0(struct sock *);
564void tcp_send_partial(struct sock *);
565int tcp_write_wakeup(struct sock *, int mib);
566void tcp_send_fin(struct sock *sk);
567void tcp_send_active_reset(struct sock *sk, gfp_t priority);
568int tcp_send_synack(struct sock *);
569void tcp_push_one(struct sock *, unsigned int mss_now);
570void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
571void tcp_send_ack(struct sock *sk);
572void tcp_send_delayed_ack(struct sock *sk);
573void tcp_send_loss_probe(struct sock *sk);
574bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
575void tcp_skb_collapse_tstamp(struct sk_buff *skb,
576 const struct sk_buff *next_skb);
577
578/* tcp_input.c */
579void tcp_rearm_rto(struct sock *sk);
580void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
581void tcp_reset(struct sock *sk);
582void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
583void tcp_fin(struct sock *sk);
584
585/* tcp_timer.c */
586void tcp_init_xmit_timers(struct sock *);
587static inline void tcp_clear_xmit_timers(struct sock *sk)
588{
589 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
590 __sock_put(sk);
591
592 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
593 __sock_put(sk);
594
595 inet_csk_clear_xmit_timers(sk);
596}
597
598unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
599unsigned int tcp_current_mss(struct sock *sk);
600
601/* Bound MSS / TSO packet size with the half of the window */
602static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
603{
604 int cutoff;
605
606 /* When peer uses tiny windows, there is no use in packetizing
607 * to sub-MSS pieces for the sake of SWS or making sure there
608 * are enough packets in the pipe for fast recovery.
609 *
610 * On the other hand, for extremely large MSS devices, handling
611 * smaller than MSS windows in this way does make sense.
612 */
613 if (tp->max_window > TCP_MSS_DEFAULT)
614 cutoff = (tp->max_window >> 1);
615 else
616 cutoff = tp->max_window;
617
618 if (cutoff && pktsize > cutoff)
619 return max_t(int, cutoff, 68U - tp->tcp_header_len);
620 else
621 return pktsize;
622}
623
624/* tcp.c */
625void tcp_get_info(struct sock *, struct tcp_info *);
626
627/* Read 'sendfile()'-style from a TCP socket */
628int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
629 sk_read_actor_t recv_actor);
630
631void tcp_initialize_rcv_mss(struct sock *sk);
632
633int tcp_mtu_to_mss(struct sock *sk, int pmtu);
634int tcp_mss_to_mtu(struct sock *sk, int mss);
635void tcp_mtup_init(struct sock *sk);
636void tcp_init_buffer_space(struct sock *sk);
637
638static inline void tcp_bound_rto(const struct sock *sk)
639{
640 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
641 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
642}
643
644static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
645{
646 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
647}
648
649static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
650{
651 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
652 ntohl(TCP_FLAG_ACK) |
653 snd_wnd);
654}
655
656static inline void tcp_fast_path_on(struct tcp_sock *tp)
657{
658 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
659}
660
661static inline void tcp_fast_path_check(struct sock *sk)
662{
663 struct tcp_sock *tp = tcp_sk(sk);
664
665 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
666 tp->rcv_wnd &&
667 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
668 !tp->urg_data)
669 tcp_fast_path_on(tp);
670}
671
672/* Compute the actual rto_min value */
673static inline u32 tcp_rto_min(struct sock *sk)
674{
675 const struct dst_entry *dst = __sk_dst_get(sk);
676 u32 rto_min = TCP_RTO_MIN;
677
678 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
679 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
680 return rto_min;
681}
682
683static inline u32 tcp_rto_min_us(struct sock *sk)
684{
685 return jiffies_to_usecs(tcp_rto_min(sk));
686}
687
688static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
689{
690 return dst_metric_locked(dst, RTAX_CC_ALGO);
691}
692
693/* Minimum RTT in usec. ~0 means not available. */
694static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
695{
696 return minmax_get(&tp->rtt_min);
697}
698
699/* Compute the actual receive window we are currently advertising.
700 * Rcv_nxt can be after the window if our peer push more data
701 * than the offered window.
702 */
703static inline u32 tcp_receive_window(const struct tcp_sock *tp)
704{
705 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
706
707 if (win < 0)
708 win = 0;
709 return (u32) win;
710}
711
712/* Choose a new window, without checks for shrinking, and without
713 * scaling applied to the result. The caller does these things
714 * if necessary. This is a "raw" window selection.
715 */
716u32 __tcp_select_window(struct sock *sk);
717
718void tcp_send_window_probe(struct sock *sk);
719
720/* TCP uses 32bit jiffies to save some space.
721 * Note that this is different from tcp_time_stamp, which
722 * historically has been the same until linux-4.13.
723 */
724#define tcp_jiffies32 ((u32)jiffies)
725
726/*
727 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
728 * It is no longer tied to jiffies, but to 1 ms clock.
729 * Note: double check if you want to use tcp_jiffies32 instead of this.
730 */
731#define TCP_TS_HZ 1000
732
733static inline u64 tcp_clock_ns(void)
734{
735 return local_clock();
736}
737
738static inline u64 tcp_clock_us(void)
739{
740 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
741}
742
743/* This should only be used in contexts where tp->tcp_mstamp is up to date */
744static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
745{
746 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
747}
748
749/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
750static inline u32 tcp_time_stamp_raw(void)
751{
752 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
753}
754
755
756/* Refresh 1us clock of a TCP socket,
757 * ensuring monotically increasing values.
758 */
759static inline void tcp_mstamp_refresh(struct tcp_sock *tp)
760{
761 u64 val = tcp_clock_us();
762
763 if (val > tp->tcp_mstamp)
764 tp->tcp_mstamp = val;
765}
766
767static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
768{
769 return max_t(s64, t1 - t0, 0);
770}
771
772static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
773{
774 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ);
775}
776
777
778#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
779
780#define TCPHDR_FIN 0x01
781#define TCPHDR_SYN 0x02
782#define TCPHDR_RST 0x04
783#define TCPHDR_PSH 0x08
784#define TCPHDR_ACK 0x10
785#define TCPHDR_URG 0x20
786#define TCPHDR_ECE 0x40
787#define TCPHDR_CWR 0x80
788
789#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
790
791/* This is what the send packet queuing engine uses to pass
792 * TCP per-packet control information to the transmission code.
793 * We also store the host-order sequence numbers in here too.
794 * This is 44 bytes if IPV6 is enabled.
795 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
796 */
797struct tcp_skb_cb {
798 __u32 seq; /* Starting sequence number */
799 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
800 union {
801 /* Note : tcp_tw_isn is used in input path only
802 * (isn chosen by tcp_timewait_state_process())
803 *
804 * tcp_gso_segs/size are used in write queue only,
805 * cf tcp_skb_pcount()/tcp_skb_mss()
806 */
807 __u32 tcp_tw_isn;
808 struct {
809 u16 tcp_gso_segs;
810 u16 tcp_gso_size;
811 };
812 };
813 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
814
815 __u8 sacked; /* State flags for SACK. */
816#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
817#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
818#define TCPCB_LOST 0x04 /* SKB is lost */
819#define TCPCB_TAGBITS 0x07 /* All tag bits */
820#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
821#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
822#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
823 TCPCB_REPAIRED)
824
825 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
826 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
827 eor:1, /* Is skb MSG_EOR marked? */
828 has_rxtstamp:1, /* SKB has a RX timestamp */
829 unused:5;
830 __u32 ack_seq; /* Sequence number ACK'd */
831 union {
832 struct {
833 /* There is space for up to 24 bytes */
834 __u32 in_flight:30,/* Bytes in flight at transmit */
835 is_app_limited:1, /* cwnd not fully used? */
836 unused:1;
837 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
838 __u32 delivered;
839 /* start of send pipeline phase */
840 u64 first_tx_mstamp;
841 /* when we reached the "delivered" count */
842 u64 delivered_mstamp;
843 } tx; /* only used for outgoing skbs */
844 union {
845 struct inet_skb_parm h4;
846#if IS_ENABLED(CONFIG_IPV6)
847 struct inet6_skb_parm h6;
848#endif
849 } header; /* For incoming skbs */
850 struct {
851 __u32 flags;
852 struct sock *sk_redir;
853 void *data_end;
854 } bpf;
855 };
856};
857
858#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
859
860static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
861{
862 TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
863}
864
865#if IS_ENABLED(CONFIG_IPV6)
866/* This is the variant of inet6_iif() that must be used by TCP,
867 * as TCP moves IP6CB into a different location in skb->cb[]
868 */
869static inline int tcp_v6_iif(const struct sk_buff *skb)
870{
871 return TCP_SKB_CB(skb)->header.h6.iif;
872}
873
874static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
875{
876 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
877
878 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
879}
880
881/* TCP_SKB_CB reference means this can not be used from early demux */
882static inline int tcp_v6_sdif(const struct sk_buff *skb)
883{
884#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
885 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
886 return TCP_SKB_CB(skb)->header.h6.iif;
887#endif
888 return 0;
889}
890#endif
891
892static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
893{
894#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
895 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
896 skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
897 return true;
898#endif
899 return false;
900}
901
902/* TCP_SKB_CB reference means this can not be used from early demux */
903static inline int tcp_v4_sdif(struct sk_buff *skb)
904{
905#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
906 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
907 return TCP_SKB_CB(skb)->header.h4.iif;
908#endif
909 return 0;
910}
911
912/* Due to TSO, an SKB can be composed of multiple actual
913 * packets. To keep these tracked properly, we use this.
914 */
915static inline int tcp_skb_pcount(const struct sk_buff *skb)
916{
917 return TCP_SKB_CB(skb)->tcp_gso_segs;
918}
919
920static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
921{
922 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
923}
924
925static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
926{
927 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
928}
929
930/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
931static inline int tcp_skb_mss(const struct sk_buff *skb)
932{
933 return TCP_SKB_CB(skb)->tcp_gso_size;
934}
935
936static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
937{
938 return likely(!TCP_SKB_CB(skb)->eor);
939}
940
941/* Events passed to congestion control interface */
942enum tcp_ca_event {
943 CA_EVENT_TX_START, /* first transmit when no packets in flight */
944 CA_EVENT_CWND_RESTART, /* congestion window restart */
945 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
946 CA_EVENT_LOSS, /* loss timeout */
947 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
948 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
949};
950
951/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
952enum tcp_ca_ack_event_flags {
953 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
954 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
955 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
956};
957
958/*
959 * Interface for adding new TCP congestion control handlers
960 */
961#define TCP_CA_NAME_MAX 16
962#define TCP_CA_MAX 128
963#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
964
965#define TCP_CA_UNSPEC 0
966
967/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
968#define TCP_CONG_NON_RESTRICTED 0x1
969/* Requires ECN/ECT set on all packets */
970#define TCP_CONG_NEEDS_ECN 0x2
971
972union tcp_cc_info;
973
974struct ack_sample {
975 u32 pkts_acked;
976 s32 rtt_us;
977 u32 in_flight;
978};
979
980/* A rate sample measures the number of (original/retransmitted) data
981 * packets delivered "delivered" over an interval of time "interval_us".
982 * The tcp_rate.c code fills in the rate sample, and congestion
983 * control modules that define a cong_control function to run at the end
984 * of ACK processing can optionally chose to consult this sample when
985 * setting cwnd and pacing rate.
986 * A sample is invalid if "delivered" or "interval_us" is negative.
987 */
988struct rate_sample {
989 u64 prior_mstamp; /* starting timestamp for interval */
990 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
991 s32 delivered; /* number of packets delivered over interval */
992 long interval_us; /* time for tp->delivered to incr "delivered" */
993 u32 snd_interval_us; /* snd interval for delivered packets */
994 u32 rcv_interval_us; /* rcv interval for delivered packets */
995 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
996 int losses; /* number of packets marked lost upon ACK */
997 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
998 u32 prior_in_flight; /* in flight before this ACK */
999 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1000 bool is_retrans; /* is sample from retransmission? */
1001 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1002};
1003
1004struct tcp_congestion_ops {
1005 struct list_head list;
1006 u32 key;
1007 u32 flags;
1008
1009 /* initialize private data (optional) */
1010 void (*init)(struct sock *sk);
1011 /* cleanup private data (optional) */
1012 void (*release)(struct sock *sk);
1013
1014 /* return slow start threshold (required) */
1015 u32 (*ssthresh)(struct sock *sk);
1016 /* do new cwnd calculation (required) */
1017 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1018 /* call before changing ca_state (optional) */
1019 void (*set_state)(struct sock *sk, u8 new_state);
1020 /* call when cwnd event occurs (optional) */
1021 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1022 /* call when ack arrives (optional) */
1023 void (*in_ack_event)(struct sock *sk, u32 flags);
1024 /* new value of cwnd after loss (required) */
1025 u32 (*undo_cwnd)(struct sock *sk);
1026 /* hook for packet ack accounting (optional) */
1027 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1028 /* override sysctl_tcp_min_tso_segs */
1029 u32 (*min_tso_segs)(struct sock *sk);
1030 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1031 u32 (*sndbuf_expand)(struct sock *sk);
1032 /* call when packets are delivered to update cwnd and pacing rate,
1033 * after all the ca_state processing. (optional)
1034 */
1035 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1036 /* get info for inet_diag (optional) */
1037 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1038 union tcp_cc_info *info);
1039
1040 char name[TCP_CA_NAME_MAX];
1041 struct module *owner;
1042};
1043
1044int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1045void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1046
1047void tcp_assign_congestion_control(struct sock *sk);
1048void tcp_init_congestion_control(struct sock *sk);
1049void tcp_cleanup_congestion_control(struct sock *sk);
1050int tcp_set_default_congestion_control(struct net *net, const char *name);
1051void tcp_get_default_congestion_control(struct net *net, char *name);
1052void tcp_get_available_congestion_control(char *buf, size_t len);
1053void tcp_get_allowed_congestion_control(char *buf, size_t len);
1054int tcp_set_allowed_congestion_control(char *allowed);
1055int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit);
1056u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1057void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1058
1059u32 tcp_reno_ssthresh(struct sock *sk);
1060u32 tcp_reno_undo_cwnd(struct sock *sk);
1061void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1062extern struct tcp_congestion_ops tcp_reno;
1063
1064struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1065u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1066#ifdef CONFIG_INET
1067char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1068#else
1069static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1070{
1071 return NULL;
1072}
1073#endif
1074
1075static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1076{
1077 const struct inet_connection_sock *icsk = inet_csk(sk);
1078
1079 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1080}
1081
1082static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1083{
1084 struct inet_connection_sock *icsk = inet_csk(sk);
1085
1086 if (icsk->icsk_ca_ops->set_state)
1087 icsk->icsk_ca_ops->set_state(sk, ca_state);
1088 icsk->icsk_ca_state = ca_state;
1089}
1090
1091static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1092{
1093 const struct inet_connection_sock *icsk = inet_csk(sk);
1094
1095 if (icsk->icsk_ca_ops->cwnd_event)
1096 icsk->icsk_ca_ops->cwnd_event(sk, event);
1097}
1098
1099/* From tcp_rate.c */
1100void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1101void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1102 struct rate_sample *rs);
1103void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1104 bool is_sack_reneg, struct rate_sample *rs);
1105void tcp_rate_check_app_limited(struct sock *sk);
1106
1107/* These functions determine how the current flow behaves in respect of SACK
1108 * handling. SACK is negotiated with the peer, and therefore it can vary
1109 * between different flows.
1110 *
1111 * tcp_is_sack - SACK enabled
1112 * tcp_is_reno - No SACK
1113 */
1114static inline int tcp_is_sack(const struct tcp_sock *tp)
1115{
1116 return tp->rx_opt.sack_ok;
1117}
1118
1119static inline bool tcp_is_reno(const struct tcp_sock *tp)
1120{
1121 return !tcp_is_sack(tp);
1122}
1123
1124static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1125{
1126 return tp->sacked_out + tp->lost_out;
1127}
1128
1129/* This determines how many packets are "in the network" to the best
1130 * of our knowledge. In many cases it is conservative, but where
1131 * detailed information is available from the receiver (via SACK
1132 * blocks etc.) we can make more aggressive calculations.
1133 *
1134 * Use this for decisions involving congestion control, use just
1135 * tp->packets_out to determine if the send queue is empty or not.
1136 *
1137 * Read this equation as:
1138 *
1139 * "Packets sent once on transmission queue" MINUS
1140 * "Packets left network, but not honestly ACKed yet" PLUS
1141 * "Packets fast retransmitted"
1142 */
1143static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1144{
1145 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1146}
1147
1148#define TCP_INFINITE_SSTHRESH 0x7fffffff
1149
1150static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1151{
1152 return tp->snd_cwnd < tp->snd_ssthresh;
1153}
1154
1155static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1156{
1157 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1158}
1159
1160static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1161{
1162 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1163 (1 << inet_csk(sk)->icsk_ca_state);
1164}
1165
1166/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1167 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1168 * ssthresh.
1169 */
1170static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1171{
1172 const struct tcp_sock *tp = tcp_sk(sk);
1173
1174 if (tcp_in_cwnd_reduction(sk))
1175 return tp->snd_ssthresh;
1176 else
1177 return max(tp->snd_ssthresh,
1178 ((tp->snd_cwnd >> 1) +
1179 (tp->snd_cwnd >> 2)));
1180}
1181
1182/* Use define here intentionally to get WARN_ON location shown at the caller */
1183#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1184
1185void tcp_enter_cwr(struct sock *sk);
1186__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1187
1188/* The maximum number of MSS of available cwnd for which TSO defers
1189 * sending if not using sysctl_tcp_tso_win_divisor.
1190 */
1191static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1192{
1193 return 3;
1194}
1195
1196/* Returns end sequence number of the receiver's advertised window */
1197static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1198{
1199 return tp->snd_una + tp->snd_wnd;
1200}
1201
1202/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1203 * flexible approach. The RFC suggests cwnd should not be raised unless
1204 * it was fully used previously. And that's exactly what we do in
1205 * congestion avoidance mode. But in slow start we allow cwnd to grow
1206 * as long as the application has used half the cwnd.
1207 * Example :
1208 * cwnd is 10 (IW10), but application sends 9 frames.
1209 * We allow cwnd to reach 18 when all frames are ACKed.
1210 * This check is safe because it's as aggressive as slow start which already
1211 * risks 100% overshoot. The advantage is that we discourage application to
1212 * either send more filler packets or data to artificially blow up the cwnd
1213 * usage, and allow application-limited process to probe bw more aggressively.
1214 */
1215static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1216{
1217 const struct tcp_sock *tp = tcp_sk(sk);
1218
1219 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1220 if (tcp_in_slow_start(tp))
1221 return tp->snd_cwnd < 2 * tp->max_packets_out;
1222
1223 return tp->is_cwnd_limited;
1224}
1225
1226/* BBR congestion control needs pacing.
1227 * Same remark for SO_MAX_PACING_RATE.
1228 * sch_fq packet scheduler is efficiently handling pacing,
1229 * but is not always installed/used.
1230 * Return true if TCP stack should pace packets itself.
1231 */
1232static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1233{
1234 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1235}
1236
1237/* Something is really bad, we could not queue an additional packet,
1238 * because qdisc is full or receiver sent a 0 window.
1239 * We do not want to add fuel to the fire, or abort too early,
1240 * so make sure the timer we arm now is at least 200ms in the future,
1241 * regardless of current icsk_rto value (as it could be ~2ms)
1242 */
1243static inline unsigned long tcp_probe0_base(const struct sock *sk)
1244{
1245 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1246}
1247
1248/* Variant of inet_csk_rto_backoff() used for zero window probes */
1249static inline unsigned long tcp_probe0_when(const struct sock *sk,
1250 unsigned long max_when)
1251{
1252 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1253
1254 return (unsigned long)min_t(u64, when, max_when);
1255}
1256
1257static inline void tcp_check_probe_timer(struct sock *sk)
1258{
1259 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1260 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1261 tcp_probe0_base(sk), TCP_RTO_MAX);
1262}
1263
1264static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1265{
1266 tp->snd_wl1 = seq;
1267}
1268
1269static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1270{
1271 tp->snd_wl1 = seq;
1272}
1273
1274/*
1275 * Calculate(/check) TCP checksum
1276 */
1277static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1278 __be32 daddr, __wsum base)
1279{
1280 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1281}
1282
1283static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1284{
1285 return __skb_checksum_complete(skb);
1286}
1287
1288static inline bool tcp_checksum_complete(struct sk_buff *skb)
1289{
1290 return !skb_csum_unnecessary(skb) &&
1291 __tcp_checksum_complete(skb);
1292}
1293
1294bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1295int tcp_filter(struct sock *sk, struct sk_buff *skb);
1296
1297#undef STATE_TRACE
1298
1299#ifdef STATE_TRACE
1300static const char *statename[]={
1301 "Unused","Established","Syn Sent","Syn Recv",
1302 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1303 "Close Wait","Last ACK","Listen","Closing"
1304};
1305#endif
1306void tcp_set_state(struct sock *sk, int state);
1307
1308void tcp_done(struct sock *sk);
1309
1310int tcp_abort(struct sock *sk, int err);
1311
1312static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1313{
1314 rx_opt->dsack = 0;
1315 rx_opt->num_sacks = 0;
1316}
1317
1318u32 tcp_default_init_rwnd(u32 mss);
1319void tcp_cwnd_restart(struct sock *sk, s32 delta);
1320
1321static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1322{
1323 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1324 struct tcp_sock *tp = tcp_sk(sk);
1325 s32 delta;
1326
1327 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1328 ca_ops->cong_control)
1329 return;
1330 delta = tcp_jiffies32 - tp->lsndtime;
1331 if (delta > inet_csk(sk)->icsk_rto)
1332 tcp_cwnd_restart(sk, delta);
1333}
1334
1335/* Determine a window scaling and initial window to offer. */
1336void tcp_select_initial_window(const struct sock *sk, int __space,
1337 __u32 mss, __u32 *rcv_wnd,
1338 __u32 *window_clamp, int wscale_ok,
1339 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1340
1341static inline int tcp_win_from_space(const struct sock *sk, int space)
1342{
1343 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1344
1345 return tcp_adv_win_scale <= 0 ?
1346 (space>>(-tcp_adv_win_scale)) :
1347 space - (space>>tcp_adv_win_scale);
1348}
1349
1350/* Note: caller must be prepared to deal with negative returns */
1351static inline int tcp_space(const struct sock *sk)
1352{
1353 return tcp_win_from_space(sk, sk->sk_rcvbuf -
1354 atomic_read(&sk->sk_rmem_alloc));
1355}
1356
1357static inline int tcp_full_space(const struct sock *sk)
1358{
1359 return tcp_win_from_space(sk, sk->sk_rcvbuf);
1360}
1361
1362extern void tcp_openreq_init_rwin(struct request_sock *req,
1363 const struct sock *sk_listener,
1364 const struct dst_entry *dst);
1365
1366void tcp_enter_memory_pressure(struct sock *sk);
1367void tcp_leave_memory_pressure(struct sock *sk);
1368
1369static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1370{
1371 struct net *net = sock_net((struct sock *)tp);
1372
1373 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1374}
1375
1376static inline int keepalive_time_when(const struct tcp_sock *tp)
1377{
1378 struct net *net = sock_net((struct sock *)tp);
1379
1380 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1381}
1382
1383static inline int keepalive_probes(const struct tcp_sock *tp)
1384{
1385 struct net *net = sock_net((struct sock *)tp);
1386
1387 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1388}
1389
1390static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1391{
1392 const struct inet_connection_sock *icsk = &tp->inet_conn;
1393
1394 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1395 tcp_jiffies32 - tp->rcv_tstamp);
1396}
1397
1398static inline int tcp_fin_time(const struct sock *sk)
1399{
1400 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1401 const int rto = inet_csk(sk)->icsk_rto;
1402
1403 if (fin_timeout < (rto << 2) - (rto >> 1))
1404 fin_timeout = (rto << 2) - (rto >> 1);
1405
1406 return fin_timeout;
1407}
1408
1409static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1410 int paws_win)
1411{
1412 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1413 return true;
1414 if (unlikely(!time_before32(ktime_get_seconds(),
1415 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1416 return true;
1417 /*
1418 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1419 * then following tcp messages have valid values. Ignore 0 value,
1420 * or else 'negative' tsval might forbid us to accept their packets.
1421 */
1422 if (!rx_opt->ts_recent)
1423 return true;
1424 return false;
1425}
1426
1427static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1428 int rst)
1429{
1430 if (tcp_paws_check(rx_opt, 0))
1431 return false;
1432
1433 /* RST segments are not recommended to carry timestamp,
1434 and, if they do, it is recommended to ignore PAWS because
1435 "their cleanup function should take precedence over timestamps."
1436 Certainly, it is mistake. It is necessary to understand the reasons
1437 of this constraint to relax it: if peer reboots, clock may go
1438 out-of-sync and half-open connections will not be reset.
1439 Actually, the problem would be not existing if all
1440 the implementations followed draft about maintaining clock
1441 via reboots. Linux-2.2 DOES NOT!
1442
1443 However, we can relax time bounds for RST segments to MSL.
1444 */
1445 if (rst && !time_before32(ktime_get_seconds(),
1446 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1447 return false;
1448 return true;
1449}
1450
1451bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1452 int mib_idx, u32 *last_oow_ack_time);
1453
1454static inline void tcp_mib_init(struct net *net)
1455{
1456 /* See RFC 2012 */
1457 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1458 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1459 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1460 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1461}
1462
1463/* from STCP */
1464static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1465{
1466 tp->lost_skb_hint = NULL;
1467}
1468
1469static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1470{
1471 tcp_clear_retrans_hints_partial(tp);
1472 tp->retransmit_skb_hint = NULL;
1473}
1474
1475union tcp_md5_addr {
1476 struct in_addr a4;
1477#if IS_ENABLED(CONFIG_IPV6)
1478 struct in6_addr a6;
1479#endif
1480};
1481
1482/* - key database */
1483struct tcp_md5sig_key {
1484 struct hlist_node node;
1485 u8 keylen;
1486 u8 family; /* AF_INET or AF_INET6 */
1487 union tcp_md5_addr addr;
1488 u8 prefixlen;
1489 u8 key[TCP_MD5SIG_MAXKEYLEN];
1490 struct rcu_head rcu;
1491};
1492
1493/* - sock block */
1494struct tcp_md5sig_info {
1495 struct hlist_head head;
1496 struct rcu_head rcu;
1497};
1498
1499/* - pseudo header */
1500struct tcp4_pseudohdr {
1501 __be32 saddr;
1502 __be32 daddr;
1503 __u8 pad;
1504 __u8 protocol;
1505 __be16 len;
1506};
1507
1508struct tcp6_pseudohdr {
1509 struct in6_addr saddr;
1510 struct in6_addr daddr;
1511 __be32 len;
1512 __be32 protocol; /* including padding */
1513};
1514
1515union tcp_md5sum_block {
1516 struct tcp4_pseudohdr ip4;
1517#if IS_ENABLED(CONFIG_IPV6)
1518 struct tcp6_pseudohdr ip6;
1519#endif
1520};
1521
1522/* - pool: digest algorithm, hash description and scratch buffer */
1523struct tcp_md5sig_pool {
1524 struct ahash_request *md5_req;
1525 void *scratch;
1526};
1527
1528/* - functions */
1529int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1530 const struct sock *sk, const struct sk_buff *skb);
1531int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1532 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
1533 gfp_t gfp);
1534int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1535 int family, u8 prefixlen);
1536struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1537 const struct sock *addr_sk);
1538
1539#ifdef CONFIG_TCP_MD5SIG
1540struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1541 const union tcp_md5_addr *addr,
1542 int family);
1543#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1544#else
1545static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1546 const union tcp_md5_addr *addr,
1547 int family)
1548{
1549 return NULL;
1550}
1551#define tcp_twsk_md5_key(twsk) NULL
1552#endif
1553
1554bool tcp_alloc_md5sig_pool(void);
1555
1556struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1557static inline void tcp_put_md5sig_pool(void)
1558{
1559 local_bh_enable();
1560}
1561
1562int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1563 unsigned int header_len);
1564int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1565 const struct tcp_md5sig_key *key);
1566
1567/* From tcp_fastopen.c */
1568void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1569 struct tcp_fastopen_cookie *cookie);
1570void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1571 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1572 u16 try_exp);
1573struct tcp_fastopen_request {
1574 /* Fast Open cookie. Size 0 means a cookie request */
1575 struct tcp_fastopen_cookie cookie;
1576 struct msghdr *data; /* data in MSG_FASTOPEN */
1577 size_t size;
1578 int copied; /* queued in tcp_connect() */
1579};
1580void tcp_free_fastopen_req(struct tcp_sock *tp);
1581void tcp_fastopen_destroy_cipher(struct sock *sk);
1582void tcp_fastopen_ctx_destroy(struct net *net);
1583int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1584 void *key, unsigned int len);
1585void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1586struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1587 struct request_sock *req,
1588 struct tcp_fastopen_cookie *foc,
1589 const struct dst_entry *dst);
1590void tcp_fastopen_init_key_once(struct net *net);
1591bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1592 struct tcp_fastopen_cookie *cookie);
1593bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1594#define TCP_FASTOPEN_KEY_LENGTH 16
1595
1596/* Fastopen key context */
1597struct tcp_fastopen_context {
1598 struct crypto_cipher *tfm;
1599 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1600 struct rcu_head rcu;
1601};
1602
1603extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1604void tcp_fastopen_active_disable(struct sock *sk);
1605bool tcp_fastopen_active_should_disable(struct sock *sk);
1606void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1607void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1608
1609/* Latencies incurred by various limits for a sender. They are
1610 * chronograph-like stats that are mutually exclusive.
1611 */
1612enum tcp_chrono {
1613 TCP_CHRONO_UNSPEC,
1614 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1615 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1616 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1617 __TCP_CHRONO_MAX,
1618};
1619
1620void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1621void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1622
1623/* This helper is needed, because skb->tcp_tsorted_anchor uses
1624 * the same memory storage than skb->destructor/_skb_refdst
1625 */
1626static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1627{
1628 skb->destructor = NULL;
1629 skb->_skb_refdst = 0UL;
1630}
1631
1632#define tcp_skb_tsorted_save(skb) { \
1633 unsigned long _save = skb->_skb_refdst; \
1634 skb->_skb_refdst = 0UL;
1635
1636#define tcp_skb_tsorted_restore(skb) \
1637 skb->_skb_refdst = _save; \
1638}
1639
1640void tcp_write_queue_purge(struct sock *sk);
1641
1642static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1643{
1644 return skb_rb_first(&sk->tcp_rtx_queue);
1645}
1646
1647static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1648{
1649 return skb_peek(&sk->sk_write_queue);
1650}
1651
1652static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1653{
1654 return skb_peek_tail(&sk->sk_write_queue);
1655}
1656
1657#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1658 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1659
1660static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1661{
1662 return skb_peek(&sk->sk_write_queue);
1663}
1664
1665static inline bool tcp_skb_is_last(const struct sock *sk,
1666 const struct sk_buff *skb)
1667{
1668 return skb_queue_is_last(&sk->sk_write_queue, skb);
1669}
1670
1671static inline bool tcp_write_queue_empty(const struct sock *sk)
1672{
1673 return skb_queue_empty(&sk->sk_write_queue);
1674}
1675
1676static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1677{
1678 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1679}
1680
1681static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1682{
1683 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1684}
1685
1686static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1687{
1688 if (tcp_write_queue_empty(sk))
1689 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1690}
1691
1692static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1693{
1694 __skb_queue_tail(&sk->sk_write_queue, skb);
1695}
1696
1697static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1698{
1699 __tcp_add_write_queue_tail(sk, skb);
1700
1701 /* Queue it, remembering where we must start sending. */
1702 if (sk->sk_write_queue.next == skb)
1703 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1704}
1705
1706/* Insert new before skb on the write queue of sk. */
1707static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1708 struct sk_buff *skb,
1709 struct sock *sk)
1710{
1711 __skb_queue_before(&sk->sk_write_queue, skb, new);
1712}
1713
1714static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1715{
1716 tcp_skb_tsorted_anchor_cleanup(skb);
1717 __skb_unlink(skb, &sk->sk_write_queue);
1718}
1719
1720void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1721
1722static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1723{
1724 tcp_skb_tsorted_anchor_cleanup(skb);
1725 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1726}
1727
1728static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1729{
1730 list_del(&skb->tcp_tsorted_anchor);
1731 tcp_rtx_queue_unlink(skb, sk);
1732 sk_wmem_free_skb(sk, skb);
1733}
1734
1735static inline void tcp_push_pending_frames(struct sock *sk)
1736{
1737 if (tcp_send_head(sk)) {
1738 struct tcp_sock *tp = tcp_sk(sk);
1739
1740 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1741 }
1742}
1743
1744/* Start sequence of the skb just after the highest skb with SACKed
1745 * bit, valid only if sacked_out > 0 or when the caller has ensured
1746 * validity by itself.
1747 */
1748static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1749{
1750 if (!tp->sacked_out)
1751 return tp->snd_una;
1752
1753 if (tp->highest_sack == NULL)
1754 return tp->snd_nxt;
1755
1756 return TCP_SKB_CB(tp->highest_sack)->seq;
1757}
1758
1759static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1760{
1761 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1762}
1763
1764static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1765{
1766 return tcp_sk(sk)->highest_sack;
1767}
1768
1769static inline void tcp_highest_sack_reset(struct sock *sk)
1770{
1771 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1772}
1773
1774/* Called when old skb is about to be deleted and replaced by new skb */
1775static inline void tcp_highest_sack_replace(struct sock *sk,
1776 struct sk_buff *old,
1777 struct sk_buff *new)
1778{
1779 if (old == tcp_highest_sack(sk))
1780 tcp_sk(sk)->highest_sack = new;
1781}
1782
1783/* This helper checks if socket has IP_TRANSPARENT set */
1784static inline bool inet_sk_transparent(const struct sock *sk)
1785{
1786 switch (sk->sk_state) {
1787 case TCP_TIME_WAIT:
1788 return inet_twsk(sk)->tw_transparent;
1789 case TCP_NEW_SYN_RECV:
1790 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1791 }
1792 return inet_sk(sk)->transparent;
1793}
1794
1795/* Determines whether this is a thin stream (which may suffer from
1796 * increased latency). Used to trigger latency-reducing mechanisms.
1797 */
1798static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1799{
1800 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1801}
1802
1803/* /proc */
1804enum tcp_seq_states {
1805 TCP_SEQ_STATE_LISTENING,
1806 TCP_SEQ_STATE_ESTABLISHED,
1807};
1808
1809void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
1810void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
1811void tcp_seq_stop(struct seq_file *seq, void *v);
1812
1813struct tcp_seq_afinfo {
1814 sa_family_t family;
1815};
1816
1817struct tcp_iter_state {
1818 struct seq_net_private p;
1819 enum tcp_seq_states state;
1820 struct sock *syn_wait_sk;
1821 int bucket, offset, sbucket, num;
1822 loff_t last_pos;
1823};
1824
1825extern struct request_sock_ops tcp_request_sock_ops;
1826extern struct request_sock_ops tcp6_request_sock_ops;
1827
1828void tcp_v4_destroy_sock(struct sock *sk);
1829
1830struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1831 netdev_features_t features);
1832struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
1833int tcp_gro_complete(struct sk_buff *skb);
1834
1835void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1836
1837static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1838{
1839 struct net *net = sock_net((struct sock *)tp);
1840 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1841}
1842
1843static inline bool tcp_stream_memory_free(const struct sock *sk)
1844{
1845 const struct tcp_sock *tp = tcp_sk(sk);
1846 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1847
1848 return notsent_bytes < tcp_notsent_lowat(tp);
1849}
1850
1851#ifdef CONFIG_PROC_FS
1852int tcp4_proc_init(void);
1853void tcp4_proc_exit(void);
1854#endif
1855
1856int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1857int tcp_conn_request(struct request_sock_ops *rsk_ops,
1858 const struct tcp_request_sock_ops *af_ops,
1859 struct sock *sk, struct sk_buff *skb);
1860
1861/* TCP af-specific functions */
1862struct tcp_sock_af_ops {
1863#ifdef CONFIG_TCP_MD5SIG
1864 struct tcp_md5sig_key *(*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 int (*md5_parse)(struct sock *sk,
1871 int optname,
1872 char __user *optval,
1873 int optlen);
1874#endif
1875};
1876
1877struct tcp_request_sock_ops {
1878 u16 mss_clamp;
1879#ifdef CONFIG_TCP_MD5SIG
1880 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1881 const struct sock *addr_sk);
1882 int (*calc_md5_hash) (char *location,
1883 const struct tcp_md5sig_key *md5,
1884 const struct sock *sk,
1885 const struct sk_buff *skb);
1886#endif
1887 void (*init_req)(struct request_sock *req,
1888 const struct sock *sk_listener,
1889 struct sk_buff *skb);
1890#ifdef CONFIG_SYN_COOKIES
1891 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1892 __u16 *mss);
1893#endif
1894 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1895 const struct request_sock *req);
1896 u32 (*init_seq)(const struct sk_buff *skb);
1897 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1898 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1899 struct flowi *fl, struct request_sock *req,
1900 struct tcp_fastopen_cookie *foc,
1901 enum tcp_synack_type synack_type);
1902};
1903
1904#ifdef CONFIG_SYN_COOKIES
1905static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1906 const struct sock *sk, struct sk_buff *skb,
1907 __u16 *mss)
1908{
1909 tcp_synq_overflow(sk);
1910 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1911 return ops->cookie_init_seq(skb, mss);
1912}
1913#else
1914static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1915 const struct sock *sk, struct sk_buff *skb,
1916 __u16 *mss)
1917{
1918 return 0;
1919}
1920#endif
1921
1922int tcpv4_offload_init(void);
1923
1924void tcp_v4_init(void);
1925void tcp_init(void);
1926
1927/* tcp_recovery.c */
1928void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
1929void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
1930extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
1931 u32 reo_wnd);
1932extern void tcp_rack_mark_lost(struct sock *sk);
1933extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
1934 u64 xmit_time);
1935extern void tcp_rack_reo_timeout(struct sock *sk);
1936extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
1937
1938/* At how many usecs into the future should the RTO fire? */
1939static inline s64 tcp_rto_delta_us(const struct sock *sk)
1940{
1941 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
1942 u32 rto = inet_csk(sk)->icsk_rto;
1943 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto);
1944
1945 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
1946}
1947
1948/*
1949 * Save and compile IPv4 options, return a pointer to it
1950 */
1951static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
1952 struct sk_buff *skb)
1953{
1954 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1955 struct ip_options_rcu *dopt = NULL;
1956
1957 if (opt->optlen) {
1958 int opt_size = sizeof(*dopt) + opt->optlen;
1959
1960 dopt = kmalloc(opt_size, GFP_ATOMIC);
1961 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
1962 kfree(dopt);
1963 dopt = NULL;
1964 }
1965 }
1966 return dopt;
1967}
1968
1969/* locally generated TCP pure ACKs have skb->truesize == 2
1970 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1971 * This is much faster than dissecting the packet to find out.
1972 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1973 */
1974static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1975{
1976 return skb->truesize == 2;
1977}
1978
1979static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1980{
1981 skb->truesize = 2;
1982}
1983
1984static inline int tcp_inq(struct sock *sk)
1985{
1986 struct tcp_sock *tp = tcp_sk(sk);
1987 int answ;
1988
1989 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1990 answ = 0;
1991 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1992 !tp->urg_data ||
1993 before(tp->urg_seq, tp->copied_seq) ||
1994 !before(tp->urg_seq, tp->rcv_nxt)) {
1995
1996 answ = tp->rcv_nxt - tp->copied_seq;
1997
1998 /* Subtract 1, if FIN was received */
1999 if (answ && sock_flag(sk, SOCK_DONE))
2000 answ--;
2001 } else {
2002 answ = tp->urg_seq - tp->copied_seq;
2003 }
2004
2005 return answ;
2006}
2007
2008int tcp_peek_len(struct socket *sock);
2009
2010static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2011{
2012 u16 segs_in;
2013
2014 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2015 tp->segs_in += segs_in;
2016 if (skb->len > tcp_hdrlen(skb))
2017 tp->data_segs_in += segs_in;
2018}
2019
2020/*
2021 * TCP listen path runs lockless.
2022 * We forced "struct sock" to be const qualified to make sure
2023 * we don't modify one of its field by mistake.
2024 * Here, we increment sk_drops which is an atomic_t, so we can safely
2025 * make sock writable again.
2026 */
2027static inline void tcp_listendrop(const struct sock *sk)
2028{
2029 atomic_inc(&((struct sock *)sk)->sk_drops);
2030 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2031}
2032
2033enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2034
2035/*
2036 * Interface for adding Upper Level Protocols over TCP
2037 */
2038
2039#define TCP_ULP_NAME_MAX 16
2040#define TCP_ULP_MAX 128
2041#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2042
2043enum {
2044 TCP_ULP_TLS,
2045 TCP_ULP_BPF,
2046};
2047
2048struct tcp_ulp_ops {
2049 struct list_head list;
2050
2051 /* initialize ulp */
2052 int (*init)(struct sock *sk);
2053 /* cleanup ulp */
2054 void (*release)(struct sock *sk);
2055
2056 int uid;
2057 char name[TCP_ULP_NAME_MAX];
2058 bool user_visible;
2059 struct module *owner;
2060};
2061int tcp_register_ulp(struct tcp_ulp_ops *type);
2062void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2063int tcp_set_ulp(struct sock *sk, const char *name);
2064int tcp_set_ulp_id(struct sock *sk, const int ulp);
2065void tcp_get_available_ulp(char *buf, size_t len);
2066void tcp_cleanup_ulp(struct sock *sk);
2067
2068#define MODULE_ALIAS_TCP_ULP(name) \
2069 __MODULE_INFO(alias, alias_userspace, name); \
2070 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2071
2072/* Call BPF_SOCK_OPS program that returns an int. If the return value
2073 * is < 0, then the BPF op failed (for example if the loaded BPF
2074 * program does not support the chosen operation or there is no BPF
2075 * program loaded).
2076 */
2077#ifdef CONFIG_BPF
2078static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2079{
2080 struct bpf_sock_ops_kern sock_ops;
2081 int ret;
2082
2083 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2084 if (sk_fullsock(sk)) {
2085 sock_ops.is_fullsock = 1;
2086 sock_owned_by_me(sk);
2087 }
2088
2089 sock_ops.sk = sk;
2090 sock_ops.op = op;
2091 if (nargs > 0)
2092 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2093
2094 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2095 if (ret == 0)
2096 ret = sock_ops.reply;
2097 else
2098 ret = -1;
2099 return ret;
2100}
2101
2102static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2103{
2104 u32 args[2] = {arg1, arg2};
2105
2106 return tcp_call_bpf(sk, op, 2, args);
2107}
2108
2109static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2110 u32 arg3)
2111{
2112 u32 args[3] = {arg1, arg2, arg3};
2113
2114 return tcp_call_bpf(sk, op, 3, args);
2115}
2116
2117#else
2118static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2119{
2120 return -EPERM;
2121}
2122
2123static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2124{
2125 return -EPERM;
2126}
2127
2128static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2129 u32 arg3)
2130{
2131 return -EPERM;
2132}
2133
2134#endif
2135
2136static inline u32 tcp_timeout_init(struct sock *sk)
2137{
2138 int timeout;
2139
2140 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2141
2142 if (timeout <= 0)
2143 timeout = TCP_TIMEOUT_INIT;
2144 return timeout;
2145}
2146
2147static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2148{
2149 int rwnd;
2150
2151 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2152
2153 if (rwnd < 0)
2154 rwnd = 0;
2155 return rwnd;
2156}
2157
2158static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2159{
2160 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2161}
2162
2163#if IS_ENABLED(CONFIG_SMC)
2164extern struct static_key_false tcp_have_smc;
2165#endif
2166
2167#if IS_ENABLED(CONFIG_TLS_DEVICE)
2168void clean_acked_data_enable(struct inet_connection_sock *icsk,
2169 void (*cad)(struct sock *sk, u32 ack_seq));
2170void clean_acked_data_disable(struct inet_connection_sock *icsk);
2171
2172#endif
2173
2174#endif /* _TCP_H */
2175