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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Definitions for the TCP module.
8 *
9 * Version: @(#)tcp.h 1.0.5 05/23/93
10 *
11 * Authors: Ross Biro
12 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 */
14#ifndef _TCP_H
15#define _TCP_H
16
17#define FASTRETRANS_DEBUG 1
18
19#include <linux/list.h>
20#include <linux/tcp.h>
21#include <linux/bug.h>
22#include <linux/slab.h>
23#include <linux/cache.h>
24#include <linux/percpu.h>
25#include <linux/skbuff.h>
26#include <linux/kref.h>
27#include <linux/ktime.h>
28#include <linux/indirect_call_wrapper.h>
29
30#include <net/inet_connection_sock.h>
31#include <net/inet_timewait_sock.h>
32#include <net/inet_hashtables.h>
33#include <net/checksum.h>
34#include <net/request_sock.h>
35#include <net/sock_reuseport.h>
36#include <net/sock.h>
37#include <net/snmp.h>
38#include <net/ip.h>
39#include <net/tcp_states.h>
40#include <net/inet_ecn.h>
41#include <net/dst.h>
42#include <net/mptcp.h>
43
44#include <linux/seq_file.h>
45#include <linux/memcontrol.h>
46#include <linux/bpf-cgroup.h>
47#include <linux/siphash.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56#define TCP_MIN_SND_MSS 48
57#define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
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 initial 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#define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
130
131#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
132#if HZ >= 100
133#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
134#define TCP_ATO_MIN ((unsigned)(HZ/25))
135#else
136#define TCP_DELACK_MIN 4U
137#define TCP_ATO_MIN 4U
138#endif
139#define TCP_RTO_MAX ((unsigned)(120*HZ))
140#define TCP_RTO_MIN ((unsigned)(HZ/5))
141#define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
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_KEEPALIVE_TIME (120*60*HZ) /* two hours */
154#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
155#define TCP_KEEPALIVE_INTVL (75*HZ)
156
157#define MAX_TCP_KEEPIDLE 32767
158#define MAX_TCP_KEEPINTVL 32767
159#define MAX_TCP_KEEPCNT 127
160#define MAX_TCP_SYNCNT 127
161
162#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
163
164#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
165#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
166 * after this time. It should be equal
167 * (or greater than) TCP_TIMEWAIT_LEN
168 * to provide reliability equal to one
169 * provided by timewait state.
170 */
171#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
172 * timestamps. It must be less than
173 * minimal timewait lifetime.
174 */
175/*
176 * TCP option
177 */
178
179#define TCPOPT_NOP 1 /* Padding */
180#define TCPOPT_EOL 0 /* End of options */
181#define TCPOPT_MSS 2 /* Segment size negotiating */
182#define TCPOPT_WINDOW 3 /* Window scaling */
183#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
184#define TCPOPT_SACK 5 /* SACK Block */
185#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
186#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
187#define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */
188#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
189#define TCPOPT_EXP 254 /* Experimental */
190/* Magic number to be after the option value for sharing TCP
191 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
192 */
193#define TCPOPT_FASTOPEN_MAGIC 0xF989
194#define TCPOPT_SMC_MAGIC 0xE2D4C3D9
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#define TCPOLEN_EXP_SMC_BASE 6
208
209/* But this is what stacks really send out. */
210#define TCPOLEN_TSTAMP_ALIGNED 12
211#define TCPOLEN_WSCALE_ALIGNED 4
212#define TCPOLEN_SACKPERM_ALIGNED 4
213#define TCPOLEN_SACK_BASE 2
214#define TCPOLEN_SACK_BASE_ALIGNED 4
215#define TCPOLEN_SACK_PERBLOCK 8
216#define TCPOLEN_MD5SIG_ALIGNED 20
217#define TCPOLEN_MSS_ALIGNED 4
218#define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
219
220/* Flags in tp->nonagle */
221#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
222#define TCP_NAGLE_CORK 2 /* Socket is corked */
223#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
224
225/* TCP thin-stream limits */
226#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
227
228/* TCP initial congestion window as per rfc6928 */
229#define TCP_INIT_CWND 10
230
231/* Bit Flags for sysctl_tcp_fastopen */
232#define TFO_CLIENT_ENABLE 1
233#define TFO_SERVER_ENABLE 2
234#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
235
236/* Accept SYN data w/o any cookie option */
237#define TFO_SERVER_COOKIE_NOT_REQD 0x200
238
239/* Force enable TFO on all listeners, i.e., not requiring the
240 * TCP_FASTOPEN socket option.
241 */
242#define TFO_SERVER_WO_SOCKOPT1 0x400
243
244
245/* sysctl variables for tcp */
246extern int sysctl_tcp_max_orphans;
247extern long sysctl_tcp_mem[3];
248
249#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
250#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
251#define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
252
253extern atomic_long_t tcp_memory_allocated;
254extern struct percpu_counter tcp_sockets_allocated;
255extern unsigned long tcp_memory_pressure;
256
257/* optimized version of sk_under_memory_pressure() for TCP sockets */
258static inline bool tcp_under_memory_pressure(const struct sock *sk)
259{
260 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
261 mem_cgroup_under_socket_pressure(sk->sk_memcg))
262 return true;
263
264 return READ_ONCE(tcp_memory_pressure);
265}
266/*
267 * The next routines deal with comparing 32 bit unsigned ints
268 * and worry about wraparound (automatic with unsigned arithmetic).
269 */
270
271static inline bool before(__u32 seq1, __u32 seq2)
272{
273 return (__s32)(seq1-seq2) < 0;
274}
275#define after(seq2, seq1) before(seq1, seq2)
276
277/* is s2<=s1<=s3 ? */
278static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
279{
280 return seq3 - seq2 >= seq1 - seq2;
281}
282
283static inline bool tcp_out_of_memory(struct sock *sk)
284{
285 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
286 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
287 return true;
288 return false;
289}
290
291void sk_forced_mem_schedule(struct sock *sk, int size);
292
293static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
294{
295 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
296 int orphans = percpu_counter_read_positive(ocp);
297
298 if (orphans << shift > sysctl_tcp_max_orphans) {
299 orphans = percpu_counter_sum_positive(ocp);
300 if (orphans << shift > sysctl_tcp_max_orphans)
301 return true;
302 }
303 return false;
304}
305
306bool tcp_check_oom(struct sock *sk, int shift);
307
308
309extern struct proto tcp_prot;
310
311#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
312#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
313#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
314#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
315
316void tcp_tasklet_init(void);
317
318int tcp_v4_err(struct sk_buff *skb, u32);
319
320void tcp_shutdown(struct sock *sk, int how);
321
322int tcp_v4_early_demux(struct sk_buff *skb);
323int tcp_v4_rcv(struct sk_buff *skb);
324
325int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
326int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
327int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
328int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
329 int flags);
330int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
331 size_t size, int flags);
332ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
333 size_t size, int flags);
334int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
335void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
336 int size_goal);
337void tcp_release_cb(struct sock *sk);
338void tcp_wfree(struct sk_buff *skb);
339void tcp_write_timer_handler(struct sock *sk);
340void tcp_delack_timer_handler(struct sock *sk);
341int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
342int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
343void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
344void tcp_rcv_space_adjust(struct sock *sk);
345int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
346void tcp_twsk_destructor(struct sock *sk);
347ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
348 struct pipe_inode_info *pipe, size_t len,
349 unsigned int flags);
350
351void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
352static inline void tcp_dec_quickack_mode(struct sock *sk,
353 const unsigned int pkts)
354{
355 struct inet_connection_sock *icsk = inet_csk(sk);
356
357 if (icsk->icsk_ack.quick) {
358 if (pkts >= icsk->icsk_ack.quick) {
359 icsk->icsk_ack.quick = 0;
360 /* Leaving quickack mode we deflate ATO. */
361 icsk->icsk_ack.ato = TCP_ATO_MIN;
362 } else
363 icsk->icsk_ack.quick -= pkts;
364 }
365}
366
367#define TCP_ECN_OK 1
368#define TCP_ECN_QUEUE_CWR 2
369#define TCP_ECN_DEMAND_CWR 4
370#define TCP_ECN_SEEN 8
371
372enum tcp_tw_status {
373 TCP_TW_SUCCESS = 0,
374 TCP_TW_RST = 1,
375 TCP_TW_ACK = 2,
376 TCP_TW_SYN = 3
377};
378
379
380enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
381 struct sk_buff *skb,
382 const struct tcphdr *th);
383struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
384 struct request_sock *req, bool fastopen,
385 bool *lost_race);
386int tcp_child_process(struct sock *parent, struct sock *child,
387 struct sk_buff *skb);
388void tcp_enter_loss(struct sock *sk);
389void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
390void tcp_clear_retrans(struct tcp_sock *tp);
391void tcp_update_metrics(struct sock *sk);
392void tcp_init_metrics(struct sock *sk);
393void tcp_metrics_init(void);
394bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
395void tcp_close(struct sock *sk, long timeout);
396void tcp_init_sock(struct sock *sk);
397void tcp_init_transfer(struct sock *sk, int bpf_op);
398__poll_t tcp_poll(struct file *file, struct socket *sock,
399 struct poll_table_struct *wait);
400int tcp_getsockopt(struct sock *sk, int level, int optname,
401 char __user *optval, int __user *optlen);
402int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
403 unsigned int optlen);
404void tcp_set_keepalive(struct sock *sk, int val);
405void tcp_syn_ack_timeout(const struct request_sock *req);
406int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
407 int flags, int *addr_len);
408int tcp_set_rcvlowat(struct sock *sk, int val);
409void tcp_data_ready(struct sock *sk);
410#ifdef CONFIG_MMU
411int tcp_mmap(struct file *file, struct socket *sock,
412 struct vm_area_struct *vma);
413#endif
414void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
415 struct tcp_options_received *opt_rx,
416 int estab, struct tcp_fastopen_cookie *foc);
417const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
418
419/*
420 * BPF SKB-less helpers
421 */
422u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
423 struct tcphdr *th, u32 *cookie);
424u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
425 struct tcphdr *th, u32 *cookie);
426u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
427 const struct tcp_request_sock_ops *af_ops,
428 struct sock *sk, struct tcphdr *th);
429/*
430 * TCP v4 functions exported for the inet6 API
431 */
432
433void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
434void tcp_v4_mtu_reduced(struct sock *sk);
435void tcp_req_err(struct sock *sk, u32 seq, bool abort);
436void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
437int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
438struct sock *tcp_create_openreq_child(const struct sock *sk,
439 struct request_sock *req,
440 struct sk_buff *skb);
441void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
442struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
443 struct request_sock *req,
444 struct dst_entry *dst,
445 struct request_sock *req_unhash,
446 bool *own_req);
447int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
448int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
449int tcp_connect(struct sock *sk);
450enum tcp_synack_type {
451 TCP_SYNACK_NORMAL,
452 TCP_SYNACK_FASTOPEN,
453 TCP_SYNACK_COOKIE,
454};
455struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
456 struct request_sock *req,
457 struct tcp_fastopen_cookie *foc,
458 enum tcp_synack_type synack_type);
459int tcp_disconnect(struct sock *sk, int flags);
460
461void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
462int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
463void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
464
465/* From syncookies.c */
466struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
467 struct request_sock *req,
468 struct dst_entry *dst, u32 tsoff);
469int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
470 u32 cookie);
471struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
472struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
473 struct sock *sk, struct sk_buff *skb);
474#ifdef CONFIG_SYN_COOKIES
475
476/* Syncookies use a monotonic timer which increments every 60 seconds.
477 * This counter is used both as a hash input and partially encoded into
478 * the cookie value. A cookie is only validated further if the delta
479 * between the current counter value and the encoded one is less than this,
480 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
481 * the counter advances immediately after a cookie is generated).
482 */
483#define MAX_SYNCOOKIE_AGE 2
484#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
485#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
486
487/* syncookies: remember time of last synqueue overflow
488 * But do not dirty this field too often (once per second is enough)
489 * It is racy as we do not hold a lock, but race is very minor.
490 */
491static inline void tcp_synq_overflow(const struct sock *sk)
492{
493 unsigned int last_overflow;
494 unsigned int now = jiffies;
495
496 if (sk->sk_reuseport) {
497 struct sock_reuseport *reuse;
498
499 reuse = rcu_dereference(sk->sk_reuseport_cb);
500 if (likely(reuse)) {
501 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
502 if (!time_between32(now, last_overflow,
503 last_overflow + HZ))
504 WRITE_ONCE(reuse->synq_overflow_ts, now);
505 return;
506 }
507 }
508
509 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
510 if (!time_between32(now, last_overflow, last_overflow + HZ))
511 WRITE_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp, now);
512}
513
514/* syncookies: no recent synqueue overflow on this listening socket? */
515static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
516{
517 unsigned int last_overflow;
518 unsigned int now = jiffies;
519
520 if (sk->sk_reuseport) {
521 struct sock_reuseport *reuse;
522
523 reuse = rcu_dereference(sk->sk_reuseport_cb);
524 if (likely(reuse)) {
525 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
526 return !time_between32(now, last_overflow - HZ,
527 last_overflow +
528 TCP_SYNCOOKIE_VALID);
529 }
530 }
531
532 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
533
534 /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
535 * then we're under synflood. However, we have to use
536 * 'last_overflow - HZ' as lower bound. That's because a concurrent
537 * tcp_synq_overflow() could update .ts_recent_stamp after we read
538 * jiffies but before we store .ts_recent_stamp into last_overflow,
539 * which could lead to rejecting a valid syncookie.
540 */
541 return !time_between32(now, last_overflow - HZ,
542 last_overflow + TCP_SYNCOOKIE_VALID);
543}
544
545static inline u32 tcp_cookie_time(void)
546{
547 u64 val = get_jiffies_64();
548
549 do_div(val, TCP_SYNCOOKIE_PERIOD);
550 return val;
551}
552
553u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
554 u16 *mssp);
555__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
556u64 cookie_init_timestamp(struct request_sock *req, u64 now);
557bool cookie_timestamp_decode(const struct net *net,
558 struct tcp_options_received *opt);
559bool cookie_ecn_ok(const struct tcp_options_received *opt,
560 const struct net *net, const struct dst_entry *dst);
561
562/* From net/ipv6/syncookies.c */
563int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
564 u32 cookie);
565struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
566
567u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
568 const struct tcphdr *th, u16 *mssp);
569__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
570#endif
571/* tcp_output.c */
572
573void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
574 int nonagle);
575int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
576int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
577void tcp_retransmit_timer(struct sock *sk);
578void tcp_xmit_retransmit_queue(struct sock *);
579void tcp_simple_retransmit(struct sock *);
580void tcp_enter_recovery(struct sock *sk, bool ece_ack);
581int tcp_trim_head(struct sock *, struct sk_buff *, u32);
582enum tcp_queue {
583 TCP_FRAG_IN_WRITE_QUEUE,
584 TCP_FRAG_IN_RTX_QUEUE,
585};
586int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
587 struct sk_buff *skb, u32 len,
588 unsigned int mss_now, gfp_t gfp);
589
590void tcp_send_probe0(struct sock *);
591void tcp_send_partial(struct sock *);
592int tcp_write_wakeup(struct sock *, int mib);
593void tcp_send_fin(struct sock *sk);
594void tcp_send_active_reset(struct sock *sk, gfp_t priority);
595int tcp_send_synack(struct sock *);
596void tcp_push_one(struct sock *, unsigned int mss_now);
597void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
598void tcp_send_ack(struct sock *sk);
599void tcp_send_delayed_ack(struct sock *sk);
600void tcp_send_loss_probe(struct sock *sk);
601bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
602void tcp_skb_collapse_tstamp(struct sk_buff *skb,
603 const struct sk_buff *next_skb);
604
605/* tcp_input.c */
606void tcp_rearm_rto(struct sock *sk);
607void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
608void tcp_reset(struct sock *sk);
609void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
610void tcp_fin(struct sock *sk);
611
612/* tcp_timer.c */
613void tcp_init_xmit_timers(struct sock *);
614static inline void tcp_clear_xmit_timers(struct sock *sk)
615{
616 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
617 __sock_put(sk);
618
619 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
620 __sock_put(sk);
621
622 inet_csk_clear_xmit_timers(sk);
623}
624
625unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
626unsigned int tcp_current_mss(struct sock *sk);
627
628/* Bound MSS / TSO packet size with the half of the window */
629static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
630{
631 int cutoff;
632
633 /* When peer uses tiny windows, there is no use in packetizing
634 * to sub-MSS pieces for the sake of SWS or making sure there
635 * are enough packets in the pipe for fast recovery.
636 *
637 * On the other hand, for extremely large MSS devices, handling
638 * smaller than MSS windows in this way does make sense.
639 */
640 if (tp->max_window > TCP_MSS_DEFAULT)
641 cutoff = (tp->max_window >> 1);
642 else
643 cutoff = tp->max_window;
644
645 if (cutoff && pktsize > cutoff)
646 return max_t(int, cutoff, 68U - tp->tcp_header_len);
647 else
648 return pktsize;
649}
650
651/* tcp.c */
652void tcp_get_info(struct sock *, struct tcp_info *);
653
654/* Read 'sendfile()'-style from a TCP socket */
655int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
656 sk_read_actor_t recv_actor);
657
658void tcp_initialize_rcv_mss(struct sock *sk);
659
660int tcp_mtu_to_mss(struct sock *sk, int pmtu);
661int tcp_mss_to_mtu(struct sock *sk, int mss);
662void tcp_mtup_init(struct sock *sk);
663
664static inline void tcp_bound_rto(const struct sock *sk)
665{
666 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
667 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
668}
669
670static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
671{
672 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
673}
674
675static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
676{
677 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
678 ntohl(TCP_FLAG_ACK) |
679 snd_wnd);
680}
681
682static inline void tcp_fast_path_on(struct tcp_sock *tp)
683{
684 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
685}
686
687static inline void tcp_fast_path_check(struct sock *sk)
688{
689 struct tcp_sock *tp = tcp_sk(sk);
690
691 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
692 tp->rcv_wnd &&
693 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
694 !tp->urg_data)
695 tcp_fast_path_on(tp);
696}
697
698/* Compute the actual rto_min value */
699static inline u32 tcp_rto_min(struct sock *sk)
700{
701 const struct dst_entry *dst = __sk_dst_get(sk);
702 u32 rto_min = TCP_RTO_MIN;
703
704 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
705 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
706 return rto_min;
707}
708
709static inline u32 tcp_rto_min_us(struct sock *sk)
710{
711 return jiffies_to_usecs(tcp_rto_min(sk));
712}
713
714static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
715{
716 return dst_metric_locked(dst, RTAX_CC_ALGO);
717}
718
719/* Minimum RTT in usec. ~0 means not available. */
720static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
721{
722 return minmax_get(&tp->rtt_min);
723}
724
725/* Compute the actual receive window we are currently advertising.
726 * Rcv_nxt can be after the window if our peer push more data
727 * than the offered window.
728 */
729static inline u32 tcp_receive_window(const struct tcp_sock *tp)
730{
731 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
732
733 if (win < 0)
734 win = 0;
735 return (u32) win;
736}
737
738/* Choose a new window, without checks for shrinking, and without
739 * scaling applied to the result. The caller does these things
740 * if necessary. This is a "raw" window selection.
741 */
742u32 __tcp_select_window(struct sock *sk);
743
744void tcp_send_window_probe(struct sock *sk);
745
746/* TCP uses 32bit jiffies to save some space.
747 * Note that this is different from tcp_time_stamp, which
748 * historically has been the same until linux-4.13.
749 */
750#define tcp_jiffies32 ((u32)jiffies)
751
752/*
753 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
754 * It is no longer tied to jiffies, but to 1 ms clock.
755 * Note: double check if you want to use tcp_jiffies32 instead of this.
756 */
757#define TCP_TS_HZ 1000
758
759static inline u64 tcp_clock_ns(void)
760{
761 return ktime_get_ns();
762}
763
764static inline u64 tcp_clock_us(void)
765{
766 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
767}
768
769/* This should only be used in contexts where tp->tcp_mstamp is up to date */
770static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
771{
772 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
773}
774
775/* Convert a nsec timestamp into TCP TSval timestamp (ms based currently) */
776static inline u32 tcp_ns_to_ts(u64 ns)
777{
778 return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ);
779}
780
781/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
782static inline u32 tcp_time_stamp_raw(void)
783{
784 return tcp_ns_to_ts(tcp_clock_ns());
785}
786
787void tcp_mstamp_refresh(struct tcp_sock *tp);
788
789static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
790{
791 return max_t(s64, t1 - t0, 0);
792}
793
794static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
795{
796 return tcp_ns_to_ts(skb->skb_mstamp_ns);
797}
798
799/* provide the departure time in us unit */
800static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
801{
802 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
803}
804
805
806#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
807
808#define TCPHDR_FIN 0x01
809#define TCPHDR_SYN 0x02
810#define TCPHDR_RST 0x04
811#define TCPHDR_PSH 0x08
812#define TCPHDR_ACK 0x10
813#define TCPHDR_URG 0x20
814#define TCPHDR_ECE 0x40
815#define TCPHDR_CWR 0x80
816
817#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
818
819/* This is what the send packet queuing engine uses to pass
820 * TCP per-packet control information to the transmission code.
821 * We also store the host-order sequence numbers in here too.
822 * This is 44 bytes if IPV6 is enabled.
823 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
824 */
825struct tcp_skb_cb {
826 __u32 seq; /* Starting sequence number */
827 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
828 union {
829 /* Note : tcp_tw_isn is used in input path only
830 * (isn chosen by tcp_timewait_state_process())
831 *
832 * tcp_gso_segs/size are used in write queue only,
833 * cf tcp_skb_pcount()/tcp_skb_mss()
834 */
835 __u32 tcp_tw_isn;
836 struct {
837 u16 tcp_gso_segs;
838 u16 tcp_gso_size;
839 };
840 };
841 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
842
843 __u8 sacked; /* State flags for SACK. */
844#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
845#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
846#define TCPCB_LOST 0x04 /* SKB is lost */
847#define TCPCB_TAGBITS 0x07 /* All tag bits */
848#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */
849#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
850#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
851 TCPCB_REPAIRED)
852
853 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
854 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
855 eor:1, /* Is skb MSG_EOR marked? */
856 has_rxtstamp:1, /* SKB has a RX timestamp */
857 unused:5;
858 __u32 ack_seq; /* Sequence number ACK'd */
859 union {
860 struct {
861 /* There is space for up to 24 bytes */
862 __u32 in_flight:30,/* Bytes in flight at transmit */
863 is_app_limited:1, /* cwnd not fully used? */
864 unused:1;
865 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
866 __u32 delivered;
867 /* start of send pipeline phase */
868 u64 first_tx_mstamp;
869 /* when we reached the "delivered" count */
870 u64 delivered_mstamp;
871 } tx; /* only used for outgoing skbs */
872 union {
873 struct inet_skb_parm h4;
874#if IS_ENABLED(CONFIG_IPV6)
875 struct inet6_skb_parm h6;
876#endif
877 } header; /* For incoming skbs */
878 struct {
879 __u32 flags;
880 struct sock *sk_redir;
881 void *data_end;
882 } bpf;
883 };
884};
885
886#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
887
888static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
889{
890 TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
891}
892
893static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb)
894{
895 return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS;
896}
897
898static inline struct sock *tcp_skb_bpf_redirect_fetch(struct sk_buff *skb)
899{
900 return TCP_SKB_CB(skb)->bpf.sk_redir;
901}
902
903static inline void tcp_skb_bpf_redirect_clear(struct sk_buff *skb)
904{
905 TCP_SKB_CB(skb)->bpf.sk_redir = NULL;
906}
907
908extern const struct inet_connection_sock_af_ops ipv4_specific;
909
910#if IS_ENABLED(CONFIG_IPV6)
911/* This is the variant of inet6_iif() that must be used by TCP,
912 * as TCP moves IP6CB into a different location in skb->cb[]
913 */
914static inline int tcp_v6_iif(const struct sk_buff *skb)
915{
916 return TCP_SKB_CB(skb)->header.h6.iif;
917}
918
919static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
920{
921 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
922
923 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
924}
925
926/* TCP_SKB_CB reference means this can not be used from early demux */
927static inline int tcp_v6_sdif(const struct sk_buff *skb)
928{
929#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
930 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
931 return TCP_SKB_CB(skb)->header.h6.iif;
932#endif
933 return 0;
934}
935
936extern const struct inet_connection_sock_af_ops ipv6_specific;
937
938INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
939INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
940INDIRECT_CALLABLE_DECLARE(void tcp_v6_early_demux(struct sk_buff *skb));
941
942#endif
943
944static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
945{
946#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
947 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
948 skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
949 return true;
950#endif
951 return false;
952}
953
954/* TCP_SKB_CB reference means this can not be used from early demux */
955static inline int tcp_v4_sdif(struct sk_buff *skb)
956{
957#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
958 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
959 return TCP_SKB_CB(skb)->header.h4.iif;
960#endif
961 return 0;
962}
963
964/* Due to TSO, an SKB can be composed of multiple actual
965 * packets. To keep these tracked properly, we use this.
966 */
967static inline int tcp_skb_pcount(const struct sk_buff *skb)
968{
969 return TCP_SKB_CB(skb)->tcp_gso_segs;
970}
971
972static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
973{
974 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
975}
976
977static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
978{
979 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
980}
981
982/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
983static inline int tcp_skb_mss(const struct sk_buff *skb)
984{
985 return TCP_SKB_CB(skb)->tcp_gso_size;
986}
987
988static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
989{
990 return likely(!TCP_SKB_CB(skb)->eor);
991}
992
993static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
994 const struct sk_buff *from)
995{
996 return likely(tcp_skb_can_collapse_to(to) &&
997 mptcp_skb_can_collapse(to, from));
998}
999
1000/* Events passed to congestion control interface */
1001enum tcp_ca_event {
1002 CA_EVENT_TX_START, /* first transmit when no packets in flight */
1003 CA_EVENT_CWND_RESTART, /* congestion window restart */
1004 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
1005 CA_EVENT_LOSS, /* loss timeout */
1006 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
1007 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
1008};
1009
1010/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1011enum tcp_ca_ack_event_flags {
1012 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
1013 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
1014 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
1015};
1016
1017/*
1018 * Interface for adding new TCP congestion control handlers
1019 */
1020#define TCP_CA_NAME_MAX 16
1021#define TCP_CA_MAX 128
1022#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
1023
1024#define TCP_CA_UNSPEC 0
1025
1026/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1027#define TCP_CONG_NON_RESTRICTED 0x1
1028/* Requires ECN/ECT set on all packets */
1029#define TCP_CONG_NEEDS_ECN 0x2
1030#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
1031
1032union tcp_cc_info;
1033
1034struct ack_sample {
1035 u32 pkts_acked;
1036 s32 rtt_us;
1037 u32 in_flight;
1038};
1039
1040/* A rate sample measures the number of (original/retransmitted) data
1041 * packets delivered "delivered" over an interval of time "interval_us".
1042 * The tcp_rate.c code fills in the rate sample, and congestion
1043 * control modules that define a cong_control function to run at the end
1044 * of ACK processing can optionally chose to consult this sample when
1045 * setting cwnd and pacing rate.
1046 * A sample is invalid if "delivered" or "interval_us" is negative.
1047 */
1048struct rate_sample {
1049 u64 prior_mstamp; /* starting timestamp for interval */
1050 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1051 s32 delivered; /* number of packets delivered over interval */
1052 long interval_us; /* time for tp->delivered to incr "delivered" */
1053 u32 snd_interval_us; /* snd interval for delivered packets */
1054 u32 rcv_interval_us; /* rcv interval for delivered packets */
1055 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1056 int losses; /* number of packets marked lost upon ACK */
1057 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1058 u32 prior_in_flight; /* in flight before this ACK */
1059 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1060 bool is_retrans; /* is sample from retransmission? */
1061 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1062};
1063
1064struct tcp_congestion_ops {
1065 struct list_head list;
1066 u32 key;
1067 u32 flags;
1068
1069 /* initialize private data (optional) */
1070 void (*init)(struct sock *sk);
1071 /* cleanup private data (optional) */
1072 void (*release)(struct sock *sk);
1073
1074 /* return slow start threshold (required) */
1075 u32 (*ssthresh)(struct sock *sk);
1076 /* do new cwnd calculation (required) */
1077 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1078 /* call before changing ca_state (optional) */
1079 void (*set_state)(struct sock *sk, u8 new_state);
1080 /* call when cwnd event occurs (optional) */
1081 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1082 /* call when ack arrives (optional) */
1083 void (*in_ack_event)(struct sock *sk, u32 flags);
1084 /* new value of cwnd after loss (required) */
1085 u32 (*undo_cwnd)(struct sock *sk);
1086 /* hook for packet ack accounting (optional) */
1087 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1088 /* override sysctl_tcp_min_tso_segs */
1089 u32 (*min_tso_segs)(struct sock *sk);
1090 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1091 u32 (*sndbuf_expand)(struct sock *sk);
1092 /* call when packets are delivered to update cwnd and pacing rate,
1093 * after all the ca_state processing. (optional)
1094 */
1095 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1096 /* get info for inet_diag (optional) */
1097 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1098 union tcp_cc_info *info);
1099
1100 char name[TCP_CA_NAME_MAX];
1101 struct module *owner;
1102};
1103
1104int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1105void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1106
1107void tcp_assign_congestion_control(struct sock *sk);
1108void tcp_init_congestion_control(struct sock *sk);
1109void tcp_cleanup_congestion_control(struct sock *sk);
1110int tcp_set_default_congestion_control(struct net *net, const char *name);
1111void tcp_get_default_congestion_control(struct net *net, char *name);
1112void tcp_get_available_congestion_control(char *buf, size_t len);
1113void tcp_get_allowed_congestion_control(char *buf, size_t len);
1114int tcp_set_allowed_congestion_control(char *allowed);
1115int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1116 bool reinit, bool cap_net_admin);
1117u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1118void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1119
1120u32 tcp_reno_ssthresh(struct sock *sk);
1121u32 tcp_reno_undo_cwnd(struct sock *sk);
1122void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1123extern struct tcp_congestion_ops tcp_reno;
1124
1125struct tcp_congestion_ops *tcp_ca_find(const char *name);
1126struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1127u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1128#ifdef CONFIG_INET
1129char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1130#else
1131static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1132{
1133 return NULL;
1134}
1135#endif
1136
1137static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1138{
1139 const struct inet_connection_sock *icsk = inet_csk(sk);
1140
1141 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1142}
1143
1144static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1145{
1146 struct inet_connection_sock *icsk = inet_csk(sk);
1147
1148 if (icsk->icsk_ca_ops->set_state)
1149 icsk->icsk_ca_ops->set_state(sk, ca_state);
1150 icsk->icsk_ca_state = ca_state;
1151}
1152
1153static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1154{
1155 const struct inet_connection_sock *icsk = inet_csk(sk);
1156
1157 if (icsk->icsk_ca_ops->cwnd_event)
1158 icsk->icsk_ca_ops->cwnd_event(sk, event);
1159}
1160
1161/* From tcp_rate.c */
1162void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1163void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1164 struct rate_sample *rs);
1165void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1166 bool is_sack_reneg, struct rate_sample *rs);
1167void tcp_rate_check_app_limited(struct sock *sk);
1168
1169/* These functions determine how the current flow behaves in respect of SACK
1170 * handling. SACK is negotiated with the peer, and therefore it can vary
1171 * between different flows.
1172 *
1173 * tcp_is_sack - SACK enabled
1174 * tcp_is_reno - No SACK
1175 */
1176static inline int tcp_is_sack(const struct tcp_sock *tp)
1177{
1178 return likely(tp->rx_opt.sack_ok);
1179}
1180
1181static inline bool tcp_is_reno(const struct tcp_sock *tp)
1182{
1183 return !tcp_is_sack(tp);
1184}
1185
1186static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1187{
1188 return tp->sacked_out + tp->lost_out;
1189}
1190
1191/* This determines how many packets are "in the network" to the best
1192 * of our knowledge. In many cases it is conservative, but where
1193 * detailed information is available from the receiver (via SACK
1194 * blocks etc.) we can make more aggressive calculations.
1195 *
1196 * Use this for decisions involving congestion control, use just
1197 * tp->packets_out to determine if the send queue is empty or not.
1198 *
1199 * Read this equation as:
1200 *
1201 * "Packets sent once on transmission queue" MINUS
1202 * "Packets left network, but not honestly ACKed yet" PLUS
1203 * "Packets fast retransmitted"
1204 */
1205static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1206{
1207 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1208}
1209
1210#define TCP_INFINITE_SSTHRESH 0x7fffffff
1211
1212static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1213{
1214 return tp->snd_cwnd < tp->snd_ssthresh;
1215}
1216
1217static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1218{
1219 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1220}
1221
1222static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1223{
1224 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1225 (1 << inet_csk(sk)->icsk_ca_state);
1226}
1227
1228/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1229 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1230 * ssthresh.
1231 */
1232static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1233{
1234 const struct tcp_sock *tp = tcp_sk(sk);
1235
1236 if (tcp_in_cwnd_reduction(sk))
1237 return tp->snd_ssthresh;
1238 else
1239 return max(tp->snd_ssthresh,
1240 ((tp->snd_cwnd >> 1) +
1241 (tp->snd_cwnd >> 2)));
1242}
1243
1244/* Use define here intentionally to get WARN_ON location shown at the caller */
1245#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1246
1247void tcp_enter_cwr(struct sock *sk);
1248__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1249
1250/* The maximum number of MSS of available cwnd for which TSO defers
1251 * sending if not using sysctl_tcp_tso_win_divisor.
1252 */
1253static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1254{
1255 return 3;
1256}
1257
1258/* Returns end sequence number of the receiver's advertised window */
1259static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1260{
1261 return tp->snd_una + tp->snd_wnd;
1262}
1263
1264/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1265 * flexible approach. The RFC suggests cwnd should not be raised unless
1266 * it was fully used previously. And that's exactly what we do in
1267 * congestion avoidance mode. But in slow start we allow cwnd to grow
1268 * as long as the application has used half the cwnd.
1269 * Example :
1270 * cwnd is 10 (IW10), but application sends 9 frames.
1271 * We allow cwnd to reach 18 when all frames are ACKed.
1272 * This check is safe because it's as aggressive as slow start which already
1273 * risks 100% overshoot. The advantage is that we discourage application to
1274 * either send more filler packets or data to artificially blow up the cwnd
1275 * usage, and allow application-limited process to probe bw more aggressively.
1276 */
1277static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1278{
1279 const struct tcp_sock *tp = tcp_sk(sk);
1280
1281 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1282 if (tcp_in_slow_start(tp))
1283 return tp->snd_cwnd < 2 * tp->max_packets_out;
1284
1285 return tp->is_cwnd_limited;
1286}
1287
1288/* BBR congestion control needs pacing.
1289 * Same remark for SO_MAX_PACING_RATE.
1290 * sch_fq packet scheduler is efficiently handling pacing,
1291 * but is not always installed/used.
1292 * Return true if TCP stack should pace packets itself.
1293 */
1294static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1295{
1296 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1297}
1298
1299/* Estimates in how many jiffies next packet for this flow can be sent.
1300 * Scheduling a retransmit timer too early would be silly.
1301 */
1302static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1303{
1304 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1305
1306 return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1307}
1308
1309static inline void tcp_reset_xmit_timer(struct sock *sk,
1310 const int what,
1311 unsigned long when,
1312 const unsigned long max_when)
1313{
1314 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1315 max_when);
1316}
1317
1318/* Something is really bad, we could not queue an additional packet,
1319 * because qdisc is full or receiver sent a 0 window, or we are paced.
1320 * We do not want to add fuel to the fire, or abort too early,
1321 * so make sure the timer we arm now is at least 200ms in the future,
1322 * regardless of current icsk_rto value (as it could be ~2ms)
1323 */
1324static inline unsigned long tcp_probe0_base(const struct sock *sk)
1325{
1326 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1327}
1328
1329/* Variant of inet_csk_rto_backoff() used for zero window probes */
1330static inline unsigned long tcp_probe0_when(const struct sock *sk,
1331 unsigned long max_when)
1332{
1333 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1334
1335 return (unsigned long)min_t(u64, when, max_when);
1336}
1337
1338static inline void tcp_check_probe_timer(struct sock *sk)
1339{
1340 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1341 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1342 tcp_probe0_base(sk), TCP_RTO_MAX);
1343}
1344
1345static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1346{
1347 tp->snd_wl1 = seq;
1348}
1349
1350static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1351{
1352 tp->snd_wl1 = seq;
1353}
1354
1355/*
1356 * Calculate(/check) TCP checksum
1357 */
1358static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1359 __be32 daddr, __wsum base)
1360{
1361 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1362}
1363
1364static inline bool tcp_checksum_complete(struct sk_buff *skb)
1365{
1366 return !skb_csum_unnecessary(skb) &&
1367 __skb_checksum_complete(skb);
1368}
1369
1370bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1371int tcp_filter(struct sock *sk, struct sk_buff *skb);
1372void tcp_set_state(struct sock *sk, int state);
1373void tcp_done(struct sock *sk);
1374int tcp_abort(struct sock *sk, int err);
1375
1376static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1377{
1378 rx_opt->dsack = 0;
1379 rx_opt->num_sacks = 0;
1380}
1381
1382void tcp_cwnd_restart(struct sock *sk, s32 delta);
1383
1384static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1385{
1386 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1387 struct tcp_sock *tp = tcp_sk(sk);
1388 s32 delta;
1389
1390 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1391 ca_ops->cong_control)
1392 return;
1393 delta = tcp_jiffies32 - tp->lsndtime;
1394 if (delta > inet_csk(sk)->icsk_rto)
1395 tcp_cwnd_restart(sk, delta);
1396}
1397
1398/* Determine a window scaling and initial window to offer. */
1399void tcp_select_initial_window(const struct sock *sk, int __space,
1400 __u32 mss, __u32 *rcv_wnd,
1401 __u32 *window_clamp, int wscale_ok,
1402 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1403
1404static inline int tcp_win_from_space(const struct sock *sk, int space)
1405{
1406 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1407
1408 return tcp_adv_win_scale <= 0 ?
1409 (space>>(-tcp_adv_win_scale)) :
1410 space - (space>>tcp_adv_win_scale);
1411}
1412
1413/* Note: caller must be prepared to deal with negative returns */
1414static inline int tcp_space(const struct sock *sk)
1415{
1416 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1417 READ_ONCE(sk->sk_backlog.len) -
1418 atomic_read(&sk->sk_rmem_alloc));
1419}
1420
1421static inline int tcp_full_space(const struct sock *sk)
1422{
1423 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1424}
1425
1426/* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1427 * If 87.5 % (7/8) of the space has been consumed, we want to override
1428 * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1429 * len/truesize ratio.
1430 */
1431static inline bool tcp_rmem_pressure(const struct sock *sk)
1432{
1433 int rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1434 int threshold = rcvbuf - (rcvbuf >> 3);
1435
1436 return atomic_read(&sk->sk_rmem_alloc) > threshold;
1437}
1438
1439extern void tcp_openreq_init_rwin(struct request_sock *req,
1440 const struct sock *sk_listener,
1441 const struct dst_entry *dst);
1442
1443void tcp_enter_memory_pressure(struct sock *sk);
1444void tcp_leave_memory_pressure(struct sock *sk);
1445
1446static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1447{
1448 struct net *net = sock_net((struct sock *)tp);
1449
1450 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1451}
1452
1453static inline int keepalive_time_when(const struct tcp_sock *tp)
1454{
1455 struct net *net = sock_net((struct sock *)tp);
1456
1457 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1458}
1459
1460static inline int keepalive_probes(const struct tcp_sock *tp)
1461{
1462 struct net *net = sock_net((struct sock *)tp);
1463
1464 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1465}
1466
1467static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1468{
1469 const struct inet_connection_sock *icsk = &tp->inet_conn;
1470
1471 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1472 tcp_jiffies32 - tp->rcv_tstamp);
1473}
1474
1475static inline int tcp_fin_time(const struct sock *sk)
1476{
1477 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1478 const int rto = inet_csk(sk)->icsk_rto;
1479
1480 if (fin_timeout < (rto << 2) - (rto >> 1))
1481 fin_timeout = (rto << 2) - (rto >> 1);
1482
1483 return fin_timeout;
1484}
1485
1486static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1487 int paws_win)
1488{
1489 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1490 return true;
1491 if (unlikely(!time_before32(ktime_get_seconds(),
1492 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1493 return true;
1494 /*
1495 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1496 * then following tcp messages have valid values. Ignore 0 value,
1497 * or else 'negative' tsval might forbid us to accept their packets.
1498 */
1499 if (!rx_opt->ts_recent)
1500 return true;
1501 return false;
1502}
1503
1504static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1505 int rst)
1506{
1507 if (tcp_paws_check(rx_opt, 0))
1508 return false;
1509
1510 /* RST segments are not recommended to carry timestamp,
1511 and, if they do, it is recommended to ignore PAWS because
1512 "their cleanup function should take precedence over timestamps."
1513 Certainly, it is mistake. It is necessary to understand the reasons
1514 of this constraint to relax it: if peer reboots, clock may go
1515 out-of-sync and half-open connections will not be reset.
1516 Actually, the problem would be not existing if all
1517 the implementations followed draft about maintaining clock
1518 via reboots. Linux-2.2 DOES NOT!
1519
1520 However, we can relax time bounds for RST segments to MSL.
1521 */
1522 if (rst && !time_before32(ktime_get_seconds(),
1523 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1524 return false;
1525 return true;
1526}
1527
1528bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1529 int mib_idx, u32 *last_oow_ack_time);
1530
1531static inline void tcp_mib_init(struct net *net)
1532{
1533 /* See RFC 2012 */
1534 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1535 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1536 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1537 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1538}
1539
1540/* from STCP */
1541static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1542{
1543 tp->lost_skb_hint = NULL;
1544}
1545
1546static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1547{
1548 tcp_clear_retrans_hints_partial(tp);
1549 tp->retransmit_skb_hint = NULL;
1550}
1551
1552union tcp_md5_addr {
1553 struct in_addr a4;
1554#if IS_ENABLED(CONFIG_IPV6)
1555 struct in6_addr a6;
1556#endif
1557};
1558
1559/* - key database */
1560struct tcp_md5sig_key {
1561 struct hlist_node node;
1562 u8 keylen;
1563 u8 family; /* AF_INET or AF_INET6 */
1564 u8 prefixlen;
1565 union tcp_md5_addr addr;
1566 int l3index; /* set if key added with L3 scope */
1567 u8 key[TCP_MD5SIG_MAXKEYLEN];
1568 struct rcu_head rcu;
1569};
1570
1571/* - sock block */
1572struct tcp_md5sig_info {
1573 struct hlist_head head;
1574 struct rcu_head rcu;
1575};
1576
1577/* - pseudo header */
1578struct tcp4_pseudohdr {
1579 __be32 saddr;
1580 __be32 daddr;
1581 __u8 pad;
1582 __u8 protocol;
1583 __be16 len;
1584};
1585
1586struct tcp6_pseudohdr {
1587 struct in6_addr saddr;
1588 struct in6_addr daddr;
1589 __be32 len;
1590 __be32 protocol; /* including padding */
1591};
1592
1593union tcp_md5sum_block {
1594 struct tcp4_pseudohdr ip4;
1595#if IS_ENABLED(CONFIG_IPV6)
1596 struct tcp6_pseudohdr ip6;
1597#endif
1598};
1599
1600/* - pool: digest algorithm, hash description and scratch buffer */
1601struct tcp_md5sig_pool {
1602 struct ahash_request *md5_req;
1603 void *scratch;
1604};
1605
1606/* - functions */
1607int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1608 const struct sock *sk, const struct sk_buff *skb);
1609int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1610 int family, u8 prefixlen, int l3index,
1611 const u8 *newkey, u8 newkeylen, gfp_t gfp);
1612int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1613 int family, u8 prefixlen, int l3index);
1614struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1615 const struct sock *addr_sk);
1616
1617#ifdef CONFIG_TCP_MD5SIG
1618#include <linux/jump_label.h>
1619extern struct static_key_false tcp_md5_needed;
1620struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1621 const union tcp_md5_addr *addr,
1622 int family);
1623static inline struct tcp_md5sig_key *
1624tcp_md5_do_lookup(const struct sock *sk, int l3index,
1625 const union tcp_md5_addr *addr, int family)
1626{
1627 if (!static_branch_unlikely(&tcp_md5_needed))
1628 return NULL;
1629 return __tcp_md5_do_lookup(sk, l3index, addr, family);
1630}
1631
1632#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1633#else
1634static inline struct tcp_md5sig_key *
1635tcp_md5_do_lookup(const struct sock *sk, int l3index,
1636 const union tcp_md5_addr *addr, int family)
1637{
1638 return NULL;
1639}
1640#define tcp_twsk_md5_key(twsk) NULL
1641#endif
1642
1643bool tcp_alloc_md5sig_pool(void);
1644
1645struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1646static inline void tcp_put_md5sig_pool(void)
1647{
1648 local_bh_enable();
1649}
1650
1651int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1652 unsigned int header_len);
1653int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1654 const struct tcp_md5sig_key *key);
1655
1656/* From tcp_fastopen.c */
1657void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1658 struct tcp_fastopen_cookie *cookie);
1659void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1660 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1661 u16 try_exp);
1662struct tcp_fastopen_request {
1663 /* Fast Open cookie. Size 0 means a cookie request */
1664 struct tcp_fastopen_cookie cookie;
1665 struct msghdr *data; /* data in MSG_FASTOPEN */
1666 size_t size;
1667 int copied; /* queued in tcp_connect() */
1668 struct ubuf_info *uarg;
1669};
1670void tcp_free_fastopen_req(struct tcp_sock *tp);
1671void tcp_fastopen_destroy_cipher(struct sock *sk);
1672void tcp_fastopen_ctx_destroy(struct net *net);
1673int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1674 void *primary_key, void *backup_key);
1675int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1676 u64 *key);
1677void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1678struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1679 struct request_sock *req,
1680 struct tcp_fastopen_cookie *foc,
1681 const struct dst_entry *dst);
1682void tcp_fastopen_init_key_once(struct net *net);
1683bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1684 struct tcp_fastopen_cookie *cookie);
1685bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1686#define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1687#define TCP_FASTOPEN_KEY_MAX 2
1688#define TCP_FASTOPEN_KEY_BUF_LENGTH \
1689 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1690
1691/* Fastopen key context */
1692struct tcp_fastopen_context {
1693 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1694 int num;
1695 struct rcu_head rcu;
1696};
1697
1698extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1699void tcp_fastopen_active_disable(struct sock *sk);
1700bool tcp_fastopen_active_should_disable(struct sock *sk);
1701void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1702void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1703
1704/* Caller needs to wrap with rcu_read_(un)lock() */
1705static inline
1706struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1707{
1708 struct tcp_fastopen_context *ctx;
1709
1710 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1711 if (!ctx)
1712 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1713 return ctx;
1714}
1715
1716static inline
1717bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1718 const struct tcp_fastopen_cookie *orig)
1719{
1720 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1721 orig->len == foc->len &&
1722 !memcmp(orig->val, foc->val, foc->len))
1723 return true;
1724 return false;
1725}
1726
1727static inline
1728int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1729{
1730 return ctx->num;
1731}
1732
1733/* Latencies incurred by various limits for a sender. They are
1734 * chronograph-like stats that are mutually exclusive.
1735 */
1736enum tcp_chrono {
1737 TCP_CHRONO_UNSPEC,
1738 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1739 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1740 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1741 __TCP_CHRONO_MAX,
1742};
1743
1744void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1745void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1746
1747/* This helper is needed, because skb->tcp_tsorted_anchor uses
1748 * the same memory storage than skb->destructor/_skb_refdst
1749 */
1750static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1751{
1752 skb->destructor = NULL;
1753 skb->_skb_refdst = 0UL;
1754}
1755
1756#define tcp_skb_tsorted_save(skb) { \
1757 unsigned long _save = skb->_skb_refdst; \
1758 skb->_skb_refdst = 0UL;
1759
1760#define tcp_skb_tsorted_restore(skb) \
1761 skb->_skb_refdst = _save; \
1762}
1763
1764void tcp_write_queue_purge(struct sock *sk);
1765
1766static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1767{
1768 return skb_rb_first(&sk->tcp_rtx_queue);
1769}
1770
1771static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1772{
1773 return skb_rb_last(&sk->tcp_rtx_queue);
1774}
1775
1776static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1777{
1778 return skb_peek(&sk->sk_write_queue);
1779}
1780
1781static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1782{
1783 return skb_peek_tail(&sk->sk_write_queue);
1784}
1785
1786#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1787 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1788
1789static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1790{
1791 return skb_peek(&sk->sk_write_queue);
1792}
1793
1794static inline bool tcp_skb_is_last(const struct sock *sk,
1795 const struct sk_buff *skb)
1796{
1797 return skb_queue_is_last(&sk->sk_write_queue, skb);
1798}
1799
1800/**
1801 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
1802 * @sk: socket
1803 *
1804 * Since the write queue can have a temporary empty skb in it,
1805 * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
1806 */
1807static inline bool tcp_write_queue_empty(const struct sock *sk)
1808{
1809 const struct tcp_sock *tp = tcp_sk(sk);
1810
1811 return tp->write_seq == tp->snd_nxt;
1812}
1813
1814static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1815{
1816 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1817}
1818
1819static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1820{
1821 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1822}
1823
1824static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1825{
1826 __skb_queue_tail(&sk->sk_write_queue, skb);
1827
1828 /* Queue it, remembering where we must start sending. */
1829 if (sk->sk_write_queue.next == skb)
1830 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1831}
1832
1833/* Insert new before skb on the write queue of sk. */
1834static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1835 struct sk_buff *skb,
1836 struct sock *sk)
1837{
1838 __skb_queue_before(&sk->sk_write_queue, skb, new);
1839}
1840
1841static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1842{
1843 tcp_skb_tsorted_anchor_cleanup(skb);
1844 __skb_unlink(skb, &sk->sk_write_queue);
1845}
1846
1847void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1848
1849static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1850{
1851 tcp_skb_tsorted_anchor_cleanup(skb);
1852 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1853}
1854
1855static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1856{
1857 list_del(&skb->tcp_tsorted_anchor);
1858 tcp_rtx_queue_unlink(skb, sk);
1859 sk_wmem_free_skb(sk, skb);
1860}
1861
1862static inline void tcp_push_pending_frames(struct sock *sk)
1863{
1864 if (tcp_send_head(sk)) {
1865 struct tcp_sock *tp = tcp_sk(sk);
1866
1867 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1868 }
1869}
1870
1871/* Start sequence of the skb just after the highest skb with SACKed
1872 * bit, valid only if sacked_out > 0 or when the caller has ensured
1873 * validity by itself.
1874 */
1875static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1876{
1877 if (!tp->sacked_out)
1878 return tp->snd_una;
1879
1880 if (tp->highest_sack == NULL)
1881 return tp->snd_nxt;
1882
1883 return TCP_SKB_CB(tp->highest_sack)->seq;
1884}
1885
1886static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1887{
1888 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1889}
1890
1891static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1892{
1893 return tcp_sk(sk)->highest_sack;
1894}
1895
1896static inline void tcp_highest_sack_reset(struct sock *sk)
1897{
1898 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1899}
1900
1901/* Called when old skb is about to be deleted and replaced by new skb */
1902static inline void tcp_highest_sack_replace(struct sock *sk,
1903 struct sk_buff *old,
1904 struct sk_buff *new)
1905{
1906 if (old == tcp_highest_sack(sk))
1907 tcp_sk(sk)->highest_sack = new;
1908}
1909
1910/* This helper checks if socket has IP_TRANSPARENT set */
1911static inline bool inet_sk_transparent(const struct sock *sk)
1912{
1913 switch (sk->sk_state) {
1914 case TCP_TIME_WAIT:
1915 return inet_twsk(sk)->tw_transparent;
1916 case TCP_NEW_SYN_RECV:
1917 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1918 }
1919 return inet_sk(sk)->transparent;
1920}
1921
1922/* Determines whether this is a thin stream (which may suffer from
1923 * increased latency). Used to trigger latency-reducing mechanisms.
1924 */
1925static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1926{
1927 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1928}
1929
1930/* /proc */
1931enum tcp_seq_states {
1932 TCP_SEQ_STATE_LISTENING,
1933 TCP_SEQ_STATE_ESTABLISHED,
1934};
1935
1936void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
1937void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
1938void tcp_seq_stop(struct seq_file *seq, void *v);
1939
1940struct tcp_seq_afinfo {
1941 sa_family_t family;
1942};
1943
1944struct tcp_iter_state {
1945 struct seq_net_private p;
1946 enum tcp_seq_states state;
1947 struct sock *syn_wait_sk;
1948 struct tcp_seq_afinfo *bpf_seq_afinfo;
1949 int bucket, offset, sbucket, num;
1950 loff_t last_pos;
1951};
1952
1953extern struct request_sock_ops tcp_request_sock_ops;
1954extern struct request_sock_ops tcp6_request_sock_ops;
1955
1956void tcp_v4_destroy_sock(struct sock *sk);
1957
1958struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1959 netdev_features_t features);
1960struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
1961INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
1962INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
1963INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
1964INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
1965int tcp_gro_complete(struct sk_buff *skb);
1966
1967void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1968
1969static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1970{
1971 struct net *net = sock_net((struct sock *)tp);
1972 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1973}
1974
1975/* @wake is one when sk_stream_write_space() calls us.
1976 * This sends EPOLLOUT only if notsent_bytes is half the limit.
1977 * This mimics the strategy used in sock_def_write_space().
1978 */
1979static inline bool tcp_stream_memory_free(const struct sock *sk, int wake)
1980{
1981 const struct tcp_sock *tp = tcp_sk(sk);
1982 u32 notsent_bytes = READ_ONCE(tp->write_seq) -
1983 READ_ONCE(tp->snd_nxt);
1984
1985 return (notsent_bytes << wake) < tcp_notsent_lowat(tp);
1986}
1987
1988#ifdef CONFIG_PROC_FS
1989int tcp4_proc_init(void);
1990void tcp4_proc_exit(void);
1991#endif
1992
1993int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1994int tcp_conn_request(struct request_sock_ops *rsk_ops,
1995 const struct tcp_request_sock_ops *af_ops,
1996 struct sock *sk, struct sk_buff *skb);
1997
1998/* TCP af-specific functions */
1999struct tcp_sock_af_ops {
2000#ifdef CONFIG_TCP_MD5SIG
2001 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
2002 const struct sock *addr_sk);
2003 int (*calc_md5_hash)(char *location,
2004 const struct tcp_md5sig_key *md5,
2005 const struct sock *sk,
2006 const struct sk_buff *skb);
2007 int (*md5_parse)(struct sock *sk,
2008 int optname,
2009 sockptr_t optval,
2010 int optlen);
2011#endif
2012};
2013
2014struct tcp_request_sock_ops {
2015 u16 mss_clamp;
2016#ifdef CONFIG_TCP_MD5SIG
2017 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2018 const struct sock *addr_sk);
2019 int (*calc_md5_hash) (char *location,
2020 const struct tcp_md5sig_key *md5,
2021 const struct sock *sk,
2022 const struct sk_buff *skb);
2023#endif
2024 void (*init_req)(struct request_sock *req,
2025 const struct sock *sk_listener,
2026 struct sk_buff *skb);
2027#ifdef CONFIG_SYN_COOKIES
2028 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
2029 __u16 *mss);
2030#endif
2031 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
2032 const struct request_sock *req);
2033 u32 (*init_seq)(const struct sk_buff *skb);
2034 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2035 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2036 struct flowi *fl, struct request_sock *req,
2037 struct tcp_fastopen_cookie *foc,
2038 enum tcp_synack_type synack_type);
2039};
2040
2041extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2042#if IS_ENABLED(CONFIG_IPV6)
2043extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2044#endif
2045
2046#ifdef CONFIG_SYN_COOKIES
2047static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2048 const struct sock *sk, struct sk_buff *skb,
2049 __u16 *mss)
2050{
2051 tcp_synq_overflow(sk);
2052 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2053 return ops->cookie_init_seq(skb, mss);
2054}
2055#else
2056static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2057 const struct sock *sk, struct sk_buff *skb,
2058 __u16 *mss)
2059{
2060 return 0;
2061}
2062#endif
2063
2064int tcpv4_offload_init(void);
2065
2066void tcp_v4_init(void);
2067void tcp_init(void);
2068
2069/* tcp_recovery.c */
2070void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2071void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2072extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2073 u32 reo_wnd);
2074extern void tcp_rack_mark_lost(struct sock *sk);
2075extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2076 u64 xmit_time);
2077extern void tcp_rack_reo_timeout(struct sock *sk);
2078extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2079
2080/* At how many usecs into the future should the RTO fire? */
2081static inline s64 tcp_rto_delta_us(const struct sock *sk)
2082{
2083 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2084 u32 rto = inet_csk(sk)->icsk_rto;
2085 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2086
2087 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2088}
2089
2090/*
2091 * Save and compile IPv4 options, return a pointer to it
2092 */
2093static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2094 struct sk_buff *skb)
2095{
2096 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2097 struct ip_options_rcu *dopt = NULL;
2098
2099 if (opt->optlen) {
2100 int opt_size = sizeof(*dopt) + opt->optlen;
2101
2102 dopt = kmalloc(opt_size, GFP_ATOMIC);
2103 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2104 kfree(dopt);
2105 dopt = NULL;
2106 }
2107 }
2108 return dopt;
2109}
2110
2111/* locally generated TCP pure ACKs have skb->truesize == 2
2112 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2113 * This is much faster than dissecting the packet to find out.
2114 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2115 */
2116static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2117{
2118 return skb->truesize == 2;
2119}
2120
2121static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2122{
2123 skb->truesize = 2;
2124}
2125
2126static inline int tcp_inq(struct sock *sk)
2127{
2128 struct tcp_sock *tp = tcp_sk(sk);
2129 int answ;
2130
2131 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2132 answ = 0;
2133 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2134 !tp->urg_data ||
2135 before(tp->urg_seq, tp->copied_seq) ||
2136 !before(tp->urg_seq, tp->rcv_nxt)) {
2137
2138 answ = tp->rcv_nxt - tp->copied_seq;
2139
2140 /* Subtract 1, if FIN was received */
2141 if (answ && sock_flag(sk, SOCK_DONE))
2142 answ--;
2143 } else {
2144 answ = tp->urg_seq - tp->copied_seq;
2145 }
2146
2147 return answ;
2148}
2149
2150int tcp_peek_len(struct socket *sock);
2151
2152static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2153{
2154 u16 segs_in;
2155
2156 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2157 tp->segs_in += segs_in;
2158 if (skb->len > tcp_hdrlen(skb))
2159 tp->data_segs_in += segs_in;
2160}
2161
2162/*
2163 * TCP listen path runs lockless.
2164 * We forced "struct sock" to be const qualified to make sure
2165 * we don't modify one of its field by mistake.
2166 * Here, we increment sk_drops which is an atomic_t, so we can safely
2167 * make sock writable again.
2168 */
2169static inline void tcp_listendrop(const struct sock *sk)
2170{
2171 atomic_inc(&((struct sock *)sk)->sk_drops);
2172 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2173}
2174
2175enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2176
2177/*
2178 * Interface for adding Upper Level Protocols over TCP
2179 */
2180
2181#define TCP_ULP_NAME_MAX 16
2182#define TCP_ULP_MAX 128
2183#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2184
2185struct tcp_ulp_ops {
2186 struct list_head list;
2187
2188 /* initialize ulp */
2189 int (*init)(struct sock *sk);
2190 /* update ulp */
2191 void (*update)(struct sock *sk, struct proto *p,
2192 void (*write_space)(struct sock *sk));
2193 /* cleanup ulp */
2194 void (*release)(struct sock *sk);
2195 /* diagnostic */
2196 int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2197 size_t (*get_info_size)(const struct sock *sk);
2198 /* clone ulp */
2199 void (*clone)(const struct request_sock *req, struct sock *newsk,
2200 const gfp_t priority);
2201
2202 char name[TCP_ULP_NAME_MAX];
2203 struct module *owner;
2204};
2205int tcp_register_ulp(struct tcp_ulp_ops *type);
2206void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2207int tcp_set_ulp(struct sock *sk, const char *name);
2208void tcp_get_available_ulp(char *buf, size_t len);
2209void tcp_cleanup_ulp(struct sock *sk);
2210void tcp_update_ulp(struct sock *sk, struct proto *p,
2211 void (*write_space)(struct sock *sk));
2212
2213#define MODULE_ALIAS_TCP_ULP(name) \
2214 __MODULE_INFO(alias, alias_userspace, name); \
2215 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2216
2217struct sk_msg;
2218struct sk_psock;
2219
2220#ifdef CONFIG_BPF_STREAM_PARSER
2221struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
2222void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2223#else
2224static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2225{
2226}
2227#endif /* CONFIG_BPF_STREAM_PARSER */
2228
2229#ifdef CONFIG_NET_SOCK_MSG
2230int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
2231 int flags);
2232int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
2233 struct msghdr *msg, int len, int flags);
2234#endif /* CONFIG_NET_SOCK_MSG */
2235
2236/* Call BPF_SOCK_OPS program that returns an int. If the return value
2237 * is < 0, then the BPF op failed (for example if the loaded BPF
2238 * program does not support the chosen operation or there is no BPF
2239 * program loaded).
2240 */
2241#ifdef CONFIG_BPF
2242static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2243{
2244 struct bpf_sock_ops_kern sock_ops;
2245 int ret;
2246
2247 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2248 if (sk_fullsock(sk)) {
2249 sock_ops.is_fullsock = 1;
2250 sock_owned_by_me(sk);
2251 }
2252
2253 sock_ops.sk = sk;
2254 sock_ops.op = op;
2255 if (nargs > 0)
2256 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2257
2258 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2259 if (ret == 0)
2260 ret = sock_ops.reply;
2261 else
2262 ret = -1;
2263 return ret;
2264}
2265
2266static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2267{
2268 u32 args[2] = {arg1, arg2};
2269
2270 return tcp_call_bpf(sk, op, 2, args);
2271}
2272
2273static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2274 u32 arg3)
2275{
2276 u32 args[3] = {arg1, arg2, arg3};
2277
2278 return tcp_call_bpf(sk, op, 3, args);
2279}
2280
2281#else
2282static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2283{
2284 return -EPERM;
2285}
2286
2287static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2288{
2289 return -EPERM;
2290}
2291
2292static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2293 u32 arg3)
2294{
2295 return -EPERM;
2296}
2297
2298#endif
2299
2300static inline u32 tcp_timeout_init(struct sock *sk)
2301{
2302 int timeout;
2303
2304 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2305
2306 if (timeout <= 0)
2307 timeout = TCP_TIMEOUT_INIT;
2308 return timeout;
2309}
2310
2311static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2312{
2313 int rwnd;
2314
2315 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2316
2317 if (rwnd < 0)
2318 rwnd = 0;
2319 return rwnd;
2320}
2321
2322static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2323{
2324 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2325}
2326
2327static inline void tcp_bpf_rtt(struct sock *sk)
2328{
2329 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2330 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2331}
2332
2333#if IS_ENABLED(CONFIG_SMC)
2334extern struct static_key_false tcp_have_smc;
2335#endif
2336
2337#if IS_ENABLED(CONFIG_TLS_DEVICE)
2338void clean_acked_data_enable(struct inet_connection_sock *icsk,
2339 void (*cad)(struct sock *sk, u32 ack_seq));
2340void clean_acked_data_disable(struct inet_connection_sock *icsk);
2341void clean_acked_data_flush(void);
2342#endif
2343
2344DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2345static inline void tcp_add_tx_delay(struct sk_buff *skb,
2346 const struct tcp_sock *tp)
2347{
2348 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2349 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2350}
2351
2352/* Compute Earliest Departure Time for some control packets
2353 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2354 */
2355static inline u64 tcp_transmit_time(const struct sock *sk)
2356{
2357 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2358 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2359 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2360
2361 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;
2362 }
2363 return 0;
2364}
2365
2366#endif /* _TCP_H */
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
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER (128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56
57/*
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
60 */
61#define MAX_TCP_WINDOW 32767U
62
63/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
64#define TCP_MIN_MSS 88U
65
66/* The least MTU to use for probing */
67#define TCP_BASE_MSS 1024
68
69/* probing interval, default to 10 minutes as per RFC4821 */
70#define TCP_PROBE_INTERVAL 600
71
72/* Specify interval when tcp mtu probing will stop */
73#define TCP_PROBE_THRESHOLD 8
74
75/* After receiving this amount of duplicate ACKs fast retransmit starts. */
76#define TCP_FASTRETRANS_THRESH 3
77
78/* Maximal number of ACKs sent quickly to accelerate slow-start. */
79#define TCP_MAX_QUICKACKS 16U
80
81/* urg_data states */
82#define TCP_URG_VALID 0x0100
83#define TCP_URG_NOTYET 0x0200
84#define TCP_URG_READ 0x0400
85
86#define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
91 */
92
93#define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
98 */
99
100#define TCP_SYN_RETRIES 6 /* This is how many retries are done
101 * when active opening a connection.
102 * RFC1122 says the minimum retry MUST
103 * be at least 180secs. Nevertheless
104 * this value is corresponding to
105 * 63secs of retransmission with the
106 * current initial RTO.
107 */
108
109#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
110 * when passive opening a connection.
111 * This is corresponding to 31secs of
112 * retransmission with the current
113 * initial RTO.
114 */
115
116#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
117 * state, about 60 seconds */
118#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
119 /* BSD style FIN_WAIT2 deadlock breaker.
120 * It used to be 3min, new value is 60sec,
121 * to combine FIN-WAIT-2 timeout with
122 * TIME-WAIT timer.
123 */
124
125#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
126#if HZ >= 100
127#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
128#define TCP_ATO_MIN ((unsigned)(HZ/25))
129#else
130#define TCP_DELACK_MIN 4U
131#define TCP_ATO_MIN 4U
132#endif
133#define TCP_RTO_MAX ((unsigned)(120*HZ))
134#define TCP_RTO_MIN ((unsigned)(HZ/5))
135#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
136#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
137 * used as a fallback RTO for the
138 * initial data transmission if no
139 * valid RTT sample has been acquired,
140 * most likely due to retrans in 3WHS.
141 */
142
143#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
144 * for local resources.
145 */
146
147#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
148#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
149#define TCP_KEEPALIVE_INTVL (75*HZ)
150
151#define MAX_TCP_KEEPIDLE 32767
152#define MAX_TCP_KEEPINTVL 32767
153#define MAX_TCP_KEEPCNT 127
154#define MAX_TCP_SYNCNT 127
155
156#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
157
158#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
159#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
160 * after this time. It should be equal
161 * (or greater than) TCP_TIMEWAIT_LEN
162 * to provide reliability equal to one
163 * provided by timewait state.
164 */
165#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
166 * timestamps. It must be less than
167 * minimal timewait lifetime.
168 */
169/*
170 * TCP option
171 */
172
173#define TCPOPT_NOP 1 /* Padding */
174#define TCPOPT_EOL 0 /* End of options */
175#define TCPOPT_MSS 2 /* Segment size negotiating */
176#define TCPOPT_WINDOW 3 /* Window scaling */
177#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
178#define TCPOPT_SACK 5 /* SACK Block */
179#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
180#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
181#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
182#define TCPOPT_EXP 254 /* Experimental */
183/* Magic number to be after the option value for sharing TCP
184 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
185 */
186#define TCPOPT_FASTOPEN_MAGIC 0xF989
187
188/*
189 * TCP option lengths
190 */
191
192#define TCPOLEN_MSS 4
193#define TCPOLEN_WINDOW 3
194#define TCPOLEN_SACK_PERM 2
195#define TCPOLEN_TIMESTAMP 10
196#define TCPOLEN_MD5SIG 18
197#define TCPOLEN_FASTOPEN_BASE 2
198#define TCPOLEN_EXP_FASTOPEN_BASE 4
199
200/* But this is what stacks really send out. */
201#define TCPOLEN_TSTAMP_ALIGNED 12
202#define TCPOLEN_WSCALE_ALIGNED 4
203#define TCPOLEN_SACKPERM_ALIGNED 4
204#define TCPOLEN_SACK_BASE 2
205#define TCPOLEN_SACK_BASE_ALIGNED 4
206#define TCPOLEN_SACK_PERBLOCK 8
207#define TCPOLEN_MD5SIG_ALIGNED 20
208#define TCPOLEN_MSS_ALIGNED 4
209
210/* Flags in tp->nonagle */
211#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
212#define TCP_NAGLE_CORK 2 /* Socket is corked */
213#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
214
215/* TCP thin-stream limits */
216#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
217
218/* TCP initial congestion window as per rfc6928 */
219#define TCP_INIT_CWND 10
220
221/* Bit Flags for sysctl_tcp_fastopen */
222#define TFO_CLIENT_ENABLE 1
223#define TFO_SERVER_ENABLE 2
224#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
225
226/* Accept SYN data w/o any cookie option */
227#define TFO_SERVER_COOKIE_NOT_REQD 0x200
228
229/* Force enable TFO on all listeners, i.e., not requiring the
230 * TCP_FASTOPEN socket option.
231 */
232#define TFO_SERVER_WO_SOCKOPT1 0x400
233
234extern struct inet_timewait_death_row tcp_death_row;
235
236/* sysctl variables for tcp */
237extern int sysctl_tcp_timestamps;
238extern int sysctl_tcp_window_scaling;
239extern int sysctl_tcp_sack;
240extern int sysctl_tcp_fastopen;
241extern int sysctl_tcp_retrans_collapse;
242extern int sysctl_tcp_stdurg;
243extern int sysctl_tcp_rfc1337;
244extern int sysctl_tcp_abort_on_overflow;
245extern int sysctl_tcp_max_orphans;
246extern int sysctl_tcp_fack;
247extern int sysctl_tcp_reordering;
248extern int sysctl_tcp_max_reordering;
249extern int sysctl_tcp_dsack;
250extern long sysctl_tcp_mem[3];
251extern int sysctl_tcp_wmem[3];
252extern int sysctl_tcp_rmem[3];
253extern int sysctl_tcp_app_win;
254extern int sysctl_tcp_adv_win_scale;
255extern int sysctl_tcp_frto;
256extern int sysctl_tcp_low_latency;
257extern int sysctl_tcp_nometrics_save;
258extern int sysctl_tcp_moderate_rcvbuf;
259extern int sysctl_tcp_tso_win_divisor;
260extern int sysctl_tcp_workaround_signed_windows;
261extern int sysctl_tcp_slow_start_after_idle;
262extern int sysctl_tcp_thin_linear_timeouts;
263extern int sysctl_tcp_thin_dupack;
264extern int sysctl_tcp_early_retrans;
265extern int sysctl_tcp_limit_output_bytes;
266extern int sysctl_tcp_challenge_ack_limit;
267extern int sysctl_tcp_min_tso_segs;
268extern int sysctl_tcp_min_rtt_wlen;
269extern int sysctl_tcp_autocorking;
270extern int sysctl_tcp_invalid_ratelimit;
271extern int sysctl_tcp_pacing_ss_ratio;
272extern int sysctl_tcp_pacing_ca_ratio;
273
274extern atomic_long_t tcp_memory_allocated;
275extern struct percpu_counter tcp_sockets_allocated;
276extern int tcp_memory_pressure;
277
278/* optimized version of sk_under_memory_pressure() for TCP sockets */
279static inline bool tcp_under_memory_pressure(const struct sock *sk)
280{
281 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
282 mem_cgroup_under_socket_pressure(sk->sk_memcg))
283 return true;
284
285 return tcp_memory_pressure;
286}
287/*
288 * The next routines deal with comparing 32 bit unsigned ints
289 * and worry about wraparound (automatic with unsigned arithmetic).
290 */
291
292static inline bool before(__u32 seq1, __u32 seq2)
293{
294 return (__s32)(seq1-seq2) < 0;
295}
296#define after(seq2, seq1) before(seq1, seq2)
297
298/* is s2<=s1<=s3 ? */
299static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
300{
301 return seq3 - seq2 >= seq1 - seq2;
302}
303
304static inline bool tcp_out_of_memory(struct sock *sk)
305{
306 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
307 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
308 return true;
309 return false;
310}
311
312void sk_forced_mem_schedule(struct sock *sk, int size);
313
314static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
315{
316 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
317 int orphans = percpu_counter_read_positive(ocp);
318
319 if (orphans << shift > sysctl_tcp_max_orphans) {
320 orphans = percpu_counter_sum_positive(ocp);
321 if (orphans << shift > sysctl_tcp_max_orphans)
322 return true;
323 }
324 return false;
325}
326
327bool tcp_check_oom(struct sock *sk, int shift);
328
329
330extern struct proto tcp_prot;
331
332#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
333#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
334#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
335#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
336
337void tcp_tasklet_init(void);
338
339void tcp_v4_err(struct sk_buff *skb, u32);
340
341void tcp_shutdown(struct sock *sk, int how);
342
343void tcp_v4_early_demux(struct sk_buff *skb);
344int tcp_v4_rcv(struct sk_buff *skb);
345
346int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
347int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
348int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
349 int flags);
350void tcp_release_cb(struct sock *sk);
351void tcp_wfree(struct sk_buff *skb);
352void tcp_write_timer_handler(struct sock *sk);
353void tcp_delack_timer_handler(struct sock *sk);
354int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
355int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
356void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
357 const struct tcphdr *th, unsigned int len);
358void tcp_rcv_space_adjust(struct sock *sk);
359int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
360void tcp_twsk_destructor(struct sock *sk);
361ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
362 struct pipe_inode_info *pipe, size_t len,
363 unsigned int flags);
364
365static inline void tcp_dec_quickack_mode(struct sock *sk,
366 const unsigned int pkts)
367{
368 struct inet_connection_sock *icsk = inet_csk(sk);
369
370 if (icsk->icsk_ack.quick) {
371 if (pkts >= icsk->icsk_ack.quick) {
372 icsk->icsk_ack.quick = 0;
373 /* Leaving quickack mode we deflate ATO. */
374 icsk->icsk_ack.ato = TCP_ATO_MIN;
375 } else
376 icsk->icsk_ack.quick -= pkts;
377 }
378}
379
380#define TCP_ECN_OK 1
381#define TCP_ECN_QUEUE_CWR 2
382#define TCP_ECN_DEMAND_CWR 4
383#define TCP_ECN_SEEN 8
384
385enum tcp_tw_status {
386 TCP_TW_SUCCESS = 0,
387 TCP_TW_RST = 1,
388 TCP_TW_ACK = 2,
389 TCP_TW_SYN = 3
390};
391
392
393enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
394 struct sk_buff *skb,
395 const struct tcphdr *th);
396struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
397 struct request_sock *req, bool fastopen);
398int tcp_child_process(struct sock *parent, struct sock *child,
399 struct sk_buff *skb);
400void tcp_enter_loss(struct sock *sk);
401void tcp_clear_retrans(struct tcp_sock *tp);
402void tcp_update_metrics(struct sock *sk);
403void tcp_init_metrics(struct sock *sk);
404void tcp_metrics_init(void);
405bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
406 bool paws_check, bool timestamps);
407bool tcp_remember_stamp(struct sock *sk);
408bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
409void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
410void tcp_disable_fack(struct tcp_sock *tp);
411void tcp_close(struct sock *sk, long timeout);
412void tcp_init_sock(struct sock *sk);
413unsigned int tcp_poll(struct file *file, struct socket *sock,
414 struct poll_table_struct *wait);
415int tcp_getsockopt(struct sock *sk, int level, int optname,
416 char __user *optval, int __user *optlen);
417int tcp_setsockopt(struct sock *sk, int level, int optname,
418 char __user *optval, unsigned int optlen);
419int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
420 char __user *optval, int __user *optlen);
421int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
422 char __user *optval, unsigned int optlen);
423void tcp_set_keepalive(struct sock *sk, int val);
424void tcp_syn_ack_timeout(const struct request_sock *req);
425int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
426 int flags, int *addr_len);
427void tcp_parse_options(const struct sk_buff *skb,
428 struct tcp_options_received *opt_rx,
429 int estab, struct tcp_fastopen_cookie *foc);
430const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
431
432/*
433 * TCP v4 functions exported for the inet6 API
434 */
435
436void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
437void tcp_v4_mtu_reduced(struct sock *sk);
438void tcp_req_err(struct sock *sk, u32 seq, bool abort);
439int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
440struct sock *tcp_create_openreq_child(const struct sock *sk,
441 struct request_sock *req,
442 struct sk_buff *skb);
443void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
444struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
445 struct request_sock *req,
446 struct dst_entry *dst,
447 struct request_sock *req_unhash,
448 bool *own_req);
449int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
450int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
451int tcp_connect(struct sock *sk);
452enum tcp_synack_type {
453 TCP_SYNACK_NORMAL,
454 TCP_SYNACK_FASTOPEN,
455 TCP_SYNACK_COOKIE,
456};
457struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
458 struct request_sock *req,
459 struct tcp_fastopen_cookie *foc,
460 enum tcp_synack_type synack_type);
461int tcp_disconnect(struct sock *sk, int flags);
462
463void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
464int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
465void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
466
467/* From syncookies.c */
468struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
469 struct request_sock *req,
470 struct dst_entry *dst);
471int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
472 u32 cookie);
473struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
474#ifdef CONFIG_SYN_COOKIES
475
476/* Syncookies use a monotonic timer which increments every 60 seconds.
477 * This counter is used both as a hash input and partially encoded into
478 * the cookie value. A cookie is only validated further if the delta
479 * between the current counter value and the encoded one is less than this,
480 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
481 * the counter advances immediately after a cookie is generated).
482 */
483#define MAX_SYNCOOKIE_AGE 2
484#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
485#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
486
487/* syncookies: remember time of last synqueue overflow
488 * But do not dirty this field too often (once per second is enough)
489 * It is racy as we do not hold a lock, but race is very minor.
490 */
491static inline void tcp_synq_overflow(const struct sock *sk)
492{
493 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
494 unsigned long now = jiffies;
495
496 if (time_after(now, last_overflow + HZ))
497 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
498}
499
500/* syncookies: no recent synqueue overflow on this listening socket? */
501static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
502{
503 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
504
505 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
506}
507
508static inline u32 tcp_cookie_time(void)
509{
510 u64 val = get_jiffies_64();
511
512 do_div(val, TCP_SYNCOOKIE_PERIOD);
513 return val;
514}
515
516u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
517 u16 *mssp);
518__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
519__u32 cookie_init_timestamp(struct request_sock *req);
520bool cookie_timestamp_decode(struct tcp_options_received *opt);
521bool cookie_ecn_ok(const struct tcp_options_received *opt,
522 const struct net *net, const struct dst_entry *dst);
523
524/* From net/ipv6/syncookies.c */
525int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
526 u32 cookie);
527struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
528
529u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
530 const struct tcphdr *th, u16 *mssp);
531__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
532#endif
533/* tcp_output.c */
534
535u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
536 int min_tso_segs);
537void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
538 int nonagle);
539bool tcp_may_send_now(struct sock *sk);
540int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
541int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
542void tcp_retransmit_timer(struct sock *sk);
543void tcp_xmit_retransmit_queue(struct sock *);
544void tcp_simple_retransmit(struct sock *);
545int tcp_trim_head(struct sock *, struct sk_buff *, u32);
546int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
547
548void tcp_send_probe0(struct sock *);
549void tcp_send_partial(struct sock *);
550int tcp_write_wakeup(struct sock *, int mib);
551void tcp_send_fin(struct sock *sk);
552void tcp_send_active_reset(struct sock *sk, gfp_t priority);
553int tcp_send_synack(struct sock *);
554void tcp_push_one(struct sock *, unsigned int mss_now);
555void tcp_send_ack(struct sock *sk);
556void tcp_send_delayed_ack(struct sock *sk);
557void tcp_send_loss_probe(struct sock *sk);
558bool tcp_schedule_loss_probe(struct sock *sk);
559void tcp_skb_collapse_tstamp(struct sk_buff *skb,
560 const struct sk_buff *next_skb);
561
562/* tcp_input.c */
563void tcp_resume_early_retransmit(struct sock *sk);
564void tcp_rearm_rto(struct sock *sk);
565void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
566void tcp_reset(struct sock *sk);
567void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
568void tcp_fin(struct sock *sk);
569
570/* tcp_timer.c */
571void tcp_init_xmit_timers(struct sock *);
572static inline void tcp_clear_xmit_timers(struct sock *sk)
573{
574 inet_csk_clear_xmit_timers(sk);
575}
576
577unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
578unsigned int tcp_current_mss(struct sock *sk);
579
580/* Bound MSS / TSO packet size with the half of the window */
581static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
582{
583 int cutoff;
584
585 /* When peer uses tiny windows, there is no use in packetizing
586 * to sub-MSS pieces for the sake of SWS or making sure there
587 * are enough packets in the pipe for fast recovery.
588 *
589 * On the other hand, for extremely large MSS devices, handling
590 * smaller than MSS windows in this way does make sense.
591 */
592 if (tp->max_window > TCP_MSS_DEFAULT)
593 cutoff = (tp->max_window >> 1);
594 else
595 cutoff = tp->max_window;
596
597 if (cutoff && pktsize > cutoff)
598 return max_t(int, cutoff, 68U - tp->tcp_header_len);
599 else
600 return pktsize;
601}
602
603/* tcp.c */
604void tcp_get_info(struct sock *, struct tcp_info *);
605
606/* Read 'sendfile()'-style from a TCP socket */
607int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
608 sk_read_actor_t recv_actor);
609
610void tcp_initialize_rcv_mss(struct sock *sk);
611
612int tcp_mtu_to_mss(struct sock *sk, int pmtu);
613int tcp_mss_to_mtu(struct sock *sk, int mss);
614void tcp_mtup_init(struct sock *sk);
615void tcp_init_buffer_space(struct sock *sk);
616
617static inline void tcp_bound_rto(const struct sock *sk)
618{
619 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
620 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
621}
622
623static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
624{
625 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
626}
627
628static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
629{
630 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
631 ntohl(TCP_FLAG_ACK) |
632 snd_wnd);
633}
634
635static inline void tcp_fast_path_on(struct tcp_sock *tp)
636{
637 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
638}
639
640static inline void tcp_fast_path_check(struct sock *sk)
641{
642 struct tcp_sock *tp = tcp_sk(sk);
643
644 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
645 tp->rcv_wnd &&
646 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
647 !tp->urg_data)
648 tcp_fast_path_on(tp);
649}
650
651/* Compute the actual rto_min value */
652static inline u32 tcp_rto_min(struct sock *sk)
653{
654 const struct dst_entry *dst = __sk_dst_get(sk);
655 u32 rto_min = TCP_RTO_MIN;
656
657 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
658 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
659 return rto_min;
660}
661
662static inline u32 tcp_rto_min_us(struct sock *sk)
663{
664 return jiffies_to_usecs(tcp_rto_min(sk));
665}
666
667static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
668{
669 return dst_metric_locked(dst, RTAX_CC_ALGO);
670}
671
672/* Minimum RTT in usec. ~0 means not available. */
673static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
674{
675 return minmax_get(&tp->rtt_min);
676}
677
678/* Compute the actual receive window we are currently advertising.
679 * Rcv_nxt can be after the window if our peer push more data
680 * than the offered window.
681 */
682static inline u32 tcp_receive_window(const struct tcp_sock *tp)
683{
684 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
685
686 if (win < 0)
687 win = 0;
688 return (u32) win;
689}
690
691/* Choose a new window, without checks for shrinking, and without
692 * scaling applied to the result. The caller does these things
693 * if necessary. This is a "raw" window selection.
694 */
695u32 __tcp_select_window(struct sock *sk);
696
697void tcp_send_window_probe(struct sock *sk);
698
699/* TCP timestamps are only 32-bits, this causes a slight
700 * complication on 64-bit systems since we store a snapshot
701 * of jiffies in the buffer control blocks below. We decided
702 * to use only the low 32-bits of jiffies and hide the ugly
703 * casts with the following macro.
704 */
705#define tcp_time_stamp ((__u32)(jiffies))
706
707static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
708{
709 return skb->skb_mstamp.stamp_jiffies;
710}
711
712
713#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
714
715#define TCPHDR_FIN 0x01
716#define TCPHDR_SYN 0x02
717#define TCPHDR_RST 0x04
718#define TCPHDR_PSH 0x08
719#define TCPHDR_ACK 0x10
720#define TCPHDR_URG 0x20
721#define TCPHDR_ECE 0x40
722#define TCPHDR_CWR 0x80
723
724#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
725
726/* This is what the send packet queuing engine uses to pass
727 * TCP per-packet control information to the transmission code.
728 * We also store the host-order sequence numbers in here too.
729 * This is 44 bytes if IPV6 is enabled.
730 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
731 */
732struct tcp_skb_cb {
733 __u32 seq; /* Starting sequence number */
734 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
735 union {
736 /* Note : tcp_tw_isn is used in input path only
737 * (isn chosen by tcp_timewait_state_process())
738 *
739 * tcp_gso_segs/size are used in write queue only,
740 * cf tcp_skb_pcount()/tcp_skb_mss()
741 */
742 __u32 tcp_tw_isn;
743 struct {
744 u16 tcp_gso_segs;
745 u16 tcp_gso_size;
746 };
747 };
748 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
749
750 __u8 sacked; /* State flags for SACK/FACK. */
751#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
752#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
753#define TCPCB_LOST 0x04 /* SKB is lost */
754#define TCPCB_TAGBITS 0x07 /* All tag bits */
755#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
756#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
757#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
758 TCPCB_REPAIRED)
759
760 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
761 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
762 eor:1, /* Is skb MSG_EOR marked? */
763 unused:6;
764 __u32 ack_seq; /* Sequence number ACK'd */
765 union {
766 struct {
767 /* There is space for up to 24 bytes */
768 __u32 in_flight:30,/* Bytes in flight at transmit */
769 is_app_limited:1, /* cwnd not fully used? */
770 unused:1;
771 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
772 __u32 delivered;
773 /* start of send pipeline phase */
774 struct skb_mstamp first_tx_mstamp;
775 /* when we reached the "delivered" count */
776 struct skb_mstamp delivered_mstamp;
777 } tx; /* only used for outgoing skbs */
778 union {
779 struct inet_skb_parm h4;
780#if IS_ENABLED(CONFIG_IPV6)
781 struct inet6_skb_parm h6;
782#endif
783 } header; /* For incoming skbs */
784 };
785};
786
787#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
788
789
790#if IS_ENABLED(CONFIG_IPV6)
791/* This is the variant of inet6_iif() that must be used by TCP,
792 * as TCP moves IP6CB into a different location in skb->cb[]
793 */
794static inline int tcp_v6_iif(const struct sk_buff *skb)
795{
796 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
797
798 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
799}
800#endif
801
802/* TCP_SKB_CB reference means this can not be used from early demux */
803static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
804{
805#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
806 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
807 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
808 return true;
809#endif
810 return false;
811}
812
813/* Due to TSO, an SKB can be composed of multiple actual
814 * packets. To keep these tracked properly, we use this.
815 */
816static inline int tcp_skb_pcount(const struct sk_buff *skb)
817{
818 return TCP_SKB_CB(skb)->tcp_gso_segs;
819}
820
821static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
822{
823 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
824}
825
826static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
827{
828 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
829}
830
831/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
832static inline int tcp_skb_mss(const struct sk_buff *skb)
833{
834 return TCP_SKB_CB(skb)->tcp_gso_size;
835}
836
837static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
838{
839 return likely(!TCP_SKB_CB(skb)->eor);
840}
841
842/* Events passed to congestion control interface */
843enum tcp_ca_event {
844 CA_EVENT_TX_START, /* first transmit when no packets in flight */
845 CA_EVENT_CWND_RESTART, /* congestion window restart */
846 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
847 CA_EVENT_LOSS, /* loss timeout */
848 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
849 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
850 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
851 CA_EVENT_NON_DELAYED_ACK,
852};
853
854/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
855enum tcp_ca_ack_event_flags {
856 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
857 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
858 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
859};
860
861/*
862 * Interface for adding new TCP congestion control handlers
863 */
864#define TCP_CA_NAME_MAX 16
865#define TCP_CA_MAX 128
866#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
867
868#define TCP_CA_UNSPEC 0
869
870/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
871#define TCP_CONG_NON_RESTRICTED 0x1
872/* Requires ECN/ECT set on all packets */
873#define TCP_CONG_NEEDS_ECN 0x2
874
875union tcp_cc_info;
876
877struct ack_sample {
878 u32 pkts_acked;
879 s32 rtt_us;
880 u32 in_flight;
881};
882
883/* A rate sample measures the number of (original/retransmitted) data
884 * packets delivered "delivered" over an interval of time "interval_us".
885 * The tcp_rate.c code fills in the rate sample, and congestion
886 * control modules that define a cong_control function to run at the end
887 * of ACK processing can optionally chose to consult this sample when
888 * setting cwnd and pacing rate.
889 * A sample is invalid if "delivered" or "interval_us" is negative.
890 */
891struct rate_sample {
892 struct skb_mstamp prior_mstamp; /* starting timestamp for interval */
893 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
894 s32 delivered; /* number of packets delivered over interval */
895 long interval_us; /* time for tp->delivered to incr "delivered" */
896 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
897 int losses; /* number of packets marked lost upon ACK */
898 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
899 u32 prior_in_flight; /* in flight before this ACK */
900 bool is_app_limited; /* is sample from packet with bubble in pipe? */
901 bool is_retrans; /* is sample from retransmission? */
902};
903
904struct tcp_congestion_ops {
905 struct list_head list;
906 u32 key;
907 u32 flags;
908
909 /* initialize private data (optional) */
910 void (*init)(struct sock *sk);
911 /* cleanup private data (optional) */
912 void (*release)(struct sock *sk);
913
914 /* return slow start threshold (required) */
915 u32 (*ssthresh)(struct sock *sk);
916 /* do new cwnd calculation (required) */
917 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
918 /* call before changing ca_state (optional) */
919 void (*set_state)(struct sock *sk, u8 new_state);
920 /* call when cwnd event occurs (optional) */
921 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
922 /* call when ack arrives (optional) */
923 void (*in_ack_event)(struct sock *sk, u32 flags);
924 /* new value of cwnd after loss (optional) */
925 u32 (*undo_cwnd)(struct sock *sk);
926 /* hook for packet ack accounting (optional) */
927 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
928 /* suggest number of segments for each skb to transmit (optional) */
929 u32 (*tso_segs_goal)(struct sock *sk);
930 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
931 u32 (*sndbuf_expand)(struct sock *sk);
932 /* call when packets are delivered to update cwnd and pacing rate,
933 * after all the ca_state processing. (optional)
934 */
935 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
936 /* get info for inet_diag (optional) */
937 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
938 union tcp_cc_info *info);
939
940 char name[TCP_CA_NAME_MAX];
941 struct module *owner;
942};
943
944int tcp_register_congestion_control(struct tcp_congestion_ops *type);
945void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
946
947void tcp_assign_congestion_control(struct sock *sk);
948void tcp_init_congestion_control(struct sock *sk);
949void tcp_cleanup_congestion_control(struct sock *sk);
950int tcp_set_default_congestion_control(const char *name);
951void tcp_get_default_congestion_control(char *name);
952void tcp_get_available_congestion_control(char *buf, size_t len);
953void tcp_get_allowed_congestion_control(char *buf, size_t len);
954int tcp_set_allowed_congestion_control(char *allowed);
955int tcp_set_congestion_control(struct sock *sk, const char *name);
956u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
957void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
958
959u32 tcp_reno_ssthresh(struct sock *sk);
960u32 tcp_reno_undo_cwnd(struct sock *sk);
961void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
962extern struct tcp_congestion_ops tcp_reno;
963
964struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
965u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
966#ifdef CONFIG_INET
967char *tcp_ca_get_name_by_key(u32 key, char *buffer);
968#else
969static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
970{
971 return NULL;
972}
973#endif
974
975static inline bool tcp_ca_needs_ecn(const struct sock *sk)
976{
977 const struct inet_connection_sock *icsk = inet_csk(sk);
978
979 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
980}
981
982static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
983{
984 struct inet_connection_sock *icsk = inet_csk(sk);
985
986 if (icsk->icsk_ca_ops->set_state)
987 icsk->icsk_ca_ops->set_state(sk, ca_state);
988 icsk->icsk_ca_state = ca_state;
989}
990
991static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
992{
993 const struct inet_connection_sock *icsk = inet_csk(sk);
994
995 if (icsk->icsk_ca_ops->cwnd_event)
996 icsk->icsk_ca_ops->cwnd_event(sk, event);
997}
998
999/* From tcp_rate.c */
1000void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1001void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1002 struct rate_sample *rs);
1003void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1004 struct skb_mstamp *now, struct rate_sample *rs);
1005void tcp_rate_check_app_limited(struct sock *sk);
1006
1007/* These functions determine how the current flow behaves in respect of SACK
1008 * handling. SACK is negotiated with the peer, and therefore it can vary
1009 * between different flows.
1010 *
1011 * tcp_is_sack - SACK enabled
1012 * tcp_is_reno - No SACK
1013 * tcp_is_fack - FACK enabled, implies SACK enabled
1014 */
1015static inline int tcp_is_sack(const struct tcp_sock *tp)
1016{
1017 return tp->rx_opt.sack_ok;
1018}
1019
1020static inline bool tcp_is_reno(const struct tcp_sock *tp)
1021{
1022 return !tcp_is_sack(tp);
1023}
1024
1025static inline bool tcp_is_fack(const struct tcp_sock *tp)
1026{
1027 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
1028}
1029
1030static inline void tcp_enable_fack(struct tcp_sock *tp)
1031{
1032 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
1033}
1034
1035/* TCP early-retransmit (ER) is similar to but more conservative than
1036 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
1037 */
1038static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
1039{
1040 struct net *net = sock_net((struct sock *)tp);
1041
1042 tp->do_early_retrans = sysctl_tcp_early_retrans &&
1043 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
1044 net->ipv4.sysctl_tcp_reordering == 3;
1045}
1046
1047static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
1048{
1049 tp->do_early_retrans = 0;
1050}
1051
1052static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1053{
1054 return tp->sacked_out + tp->lost_out;
1055}
1056
1057/* This determines how many packets are "in the network" to the best
1058 * of our knowledge. In many cases it is conservative, but where
1059 * detailed information is available from the receiver (via SACK
1060 * blocks etc.) we can make more aggressive calculations.
1061 *
1062 * Use this for decisions involving congestion control, use just
1063 * tp->packets_out to determine if the send queue is empty or not.
1064 *
1065 * Read this equation as:
1066 *
1067 * "Packets sent once on transmission queue" MINUS
1068 * "Packets left network, but not honestly ACKed yet" PLUS
1069 * "Packets fast retransmitted"
1070 */
1071static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1072{
1073 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1074}
1075
1076#define TCP_INFINITE_SSTHRESH 0x7fffffff
1077
1078static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1079{
1080 return tp->snd_cwnd < tp->snd_ssthresh;
1081}
1082
1083static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1084{
1085 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1086}
1087
1088static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1089{
1090 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1091 (1 << inet_csk(sk)->icsk_ca_state);
1092}
1093
1094/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1095 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1096 * ssthresh.
1097 */
1098static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1099{
1100 const struct tcp_sock *tp = tcp_sk(sk);
1101
1102 if (tcp_in_cwnd_reduction(sk))
1103 return tp->snd_ssthresh;
1104 else
1105 return max(tp->snd_ssthresh,
1106 ((tp->snd_cwnd >> 1) +
1107 (tp->snd_cwnd >> 2)));
1108}
1109
1110/* Use define here intentionally to get WARN_ON location shown at the caller */
1111#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1112
1113void tcp_enter_cwr(struct sock *sk);
1114__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1115
1116/* The maximum number of MSS of available cwnd for which TSO defers
1117 * sending if not using sysctl_tcp_tso_win_divisor.
1118 */
1119static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1120{
1121 return 3;
1122}
1123
1124/* Returns end sequence number of the receiver's advertised window */
1125static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1126{
1127 return tp->snd_una + tp->snd_wnd;
1128}
1129
1130/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1131 * flexible approach. The RFC suggests cwnd should not be raised unless
1132 * it was fully used previously. And that's exactly what we do in
1133 * congestion avoidance mode. But in slow start we allow cwnd to grow
1134 * as long as the application has used half the cwnd.
1135 * Example :
1136 * cwnd is 10 (IW10), but application sends 9 frames.
1137 * We allow cwnd to reach 18 when all frames are ACKed.
1138 * This check is safe because it's as aggressive as slow start which already
1139 * risks 100% overshoot. The advantage is that we discourage application to
1140 * either send more filler packets or data to artificially blow up the cwnd
1141 * usage, and allow application-limited process to probe bw more aggressively.
1142 */
1143static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1144{
1145 const struct tcp_sock *tp = tcp_sk(sk);
1146
1147 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1148 if (tcp_in_slow_start(tp))
1149 return tp->snd_cwnd < 2 * tp->max_packets_out;
1150
1151 return tp->is_cwnd_limited;
1152}
1153
1154/* Something is really bad, we could not queue an additional packet,
1155 * because qdisc is full or receiver sent a 0 window.
1156 * We do not want to add fuel to the fire, or abort too early,
1157 * so make sure the timer we arm now is at least 200ms in the future,
1158 * regardless of current icsk_rto value (as it could be ~2ms)
1159 */
1160static inline unsigned long tcp_probe0_base(const struct sock *sk)
1161{
1162 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1163}
1164
1165/* Variant of inet_csk_rto_backoff() used for zero window probes */
1166static inline unsigned long tcp_probe0_when(const struct sock *sk,
1167 unsigned long max_when)
1168{
1169 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1170
1171 return (unsigned long)min_t(u64, when, max_when);
1172}
1173
1174static inline void tcp_check_probe_timer(struct sock *sk)
1175{
1176 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1177 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1178 tcp_probe0_base(sk), TCP_RTO_MAX);
1179}
1180
1181static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1182{
1183 tp->snd_wl1 = seq;
1184}
1185
1186static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1187{
1188 tp->snd_wl1 = seq;
1189}
1190
1191/*
1192 * Calculate(/check) TCP checksum
1193 */
1194static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1195 __be32 daddr, __wsum base)
1196{
1197 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1198}
1199
1200static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1201{
1202 return __skb_checksum_complete(skb);
1203}
1204
1205static inline bool tcp_checksum_complete(struct sk_buff *skb)
1206{
1207 return !skb_csum_unnecessary(skb) &&
1208 __tcp_checksum_complete(skb);
1209}
1210
1211/* Prequeue for VJ style copy to user, combined with checksumming. */
1212
1213static inline void tcp_prequeue_init(struct tcp_sock *tp)
1214{
1215 tp->ucopy.task = NULL;
1216 tp->ucopy.len = 0;
1217 tp->ucopy.memory = 0;
1218 skb_queue_head_init(&tp->ucopy.prequeue);
1219}
1220
1221bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1222bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1223int tcp_filter(struct sock *sk, struct sk_buff *skb);
1224
1225#undef STATE_TRACE
1226
1227#ifdef STATE_TRACE
1228static const char *statename[]={
1229 "Unused","Established","Syn Sent","Syn Recv",
1230 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1231 "Close Wait","Last ACK","Listen","Closing"
1232};
1233#endif
1234void tcp_set_state(struct sock *sk, int state);
1235
1236void tcp_done(struct sock *sk);
1237
1238int tcp_abort(struct sock *sk, int err);
1239
1240static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1241{
1242 rx_opt->dsack = 0;
1243 rx_opt->num_sacks = 0;
1244}
1245
1246u32 tcp_default_init_rwnd(u32 mss);
1247void tcp_cwnd_restart(struct sock *sk, s32 delta);
1248
1249static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1250{
1251 struct tcp_sock *tp = tcp_sk(sk);
1252 s32 delta;
1253
1254 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out)
1255 return;
1256 delta = tcp_time_stamp - tp->lsndtime;
1257 if (delta > inet_csk(sk)->icsk_rto)
1258 tcp_cwnd_restart(sk, delta);
1259}
1260
1261/* Determine a window scaling and initial window to offer. */
1262void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1263 __u32 *window_clamp, int wscale_ok,
1264 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1265
1266static inline int tcp_win_from_space(int space)
1267{
1268 return sysctl_tcp_adv_win_scale<=0 ?
1269 (space>>(-sysctl_tcp_adv_win_scale)) :
1270 space - (space>>sysctl_tcp_adv_win_scale);
1271}
1272
1273/* Note: caller must be prepared to deal with negative returns */
1274static inline int tcp_space(const struct sock *sk)
1275{
1276 return tcp_win_from_space(sk->sk_rcvbuf -
1277 atomic_read(&sk->sk_rmem_alloc));
1278}
1279
1280static inline int tcp_full_space(const struct sock *sk)
1281{
1282 return tcp_win_from_space(sk->sk_rcvbuf);
1283}
1284
1285extern void tcp_openreq_init_rwin(struct request_sock *req,
1286 const struct sock *sk_listener,
1287 const struct dst_entry *dst);
1288
1289void tcp_enter_memory_pressure(struct sock *sk);
1290
1291static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1292{
1293 struct net *net = sock_net((struct sock *)tp);
1294
1295 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1296}
1297
1298static inline int keepalive_time_when(const struct tcp_sock *tp)
1299{
1300 struct net *net = sock_net((struct sock *)tp);
1301
1302 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1303}
1304
1305static inline int keepalive_probes(const struct tcp_sock *tp)
1306{
1307 struct net *net = sock_net((struct sock *)tp);
1308
1309 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1310}
1311
1312static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1313{
1314 const struct inet_connection_sock *icsk = &tp->inet_conn;
1315
1316 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1317 tcp_time_stamp - tp->rcv_tstamp);
1318}
1319
1320static inline int tcp_fin_time(const struct sock *sk)
1321{
1322 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1323 const int rto = inet_csk(sk)->icsk_rto;
1324
1325 if (fin_timeout < (rto << 2) - (rto >> 1))
1326 fin_timeout = (rto << 2) - (rto >> 1);
1327
1328 return fin_timeout;
1329}
1330
1331static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1332 int paws_win)
1333{
1334 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1335 return true;
1336 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1337 return true;
1338 /*
1339 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1340 * then following tcp messages have valid values. Ignore 0 value,
1341 * or else 'negative' tsval might forbid us to accept their packets.
1342 */
1343 if (!rx_opt->ts_recent)
1344 return true;
1345 return false;
1346}
1347
1348static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1349 int rst)
1350{
1351 if (tcp_paws_check(rx_opt, 0))
1352 return false;
1353
1354 /* RST segments are not recommended to carry timestamp,
1355 and, if they do, it is recommended to ignore PAWS because
1356 "their cleanup function should take precedence over timestamps."
1357 Certainly, it is mistake. It is necessary to understand the reasons
1358 of this constraint to relax it: if peer reboots, clock may go
1359 out-of-sync and half-open connections will not be reset.
1360 Actually, the problem would be not existing if all
1361 the implementations followed draft about maintaining clock
1362 via reboots. Linux-2.2 DOES NOT!
1363
1364 However, we can relax time bounds for RST segments to MSL.
1365 */
1366 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1367 return false;
1368 return true;
1369}
1370
1371bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1372 int mib_idx, u32 *last_oow_ack_time);
1373
1374static inline void tcp_mib_init(struct net *net)
1375{
1376 /* See RFC 2012 */
1377 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1378 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1379 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1380 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1381}
1382
1383/* from STCP */
1384static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1385{
1386 tp->lost_skb_hint = NULL;
1387}
1388
1389static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1390{
1391 tcp_clear_retrans_hints_partial(tp);
1392 tp->retransmit_skb_hint = NULL;
1393}
1394
1395union tcp_md5_addr {
1396 struct in_addr a4;
1397#if IS_ENABLED(CONFIG_IPV6)
1398 struct in6_addr a6;
1399#endif
1400};
1401
1402/* - key database */
1403struct tcp_md5sig_key {
1404 struct hlist_node node;
1405 u8 keylen;
1406 u8 family; /* AF_INET or AF_INET6 */
1407 union tcp_md5_addr addr;
1408 u8 key[TCP_MD5SIG_MAXKEYLEN];
1409 struct rcu_head rcu;
1410};
1411
1412/* - sock block */
1413struct tcp_md5sig_info {
1414 struct hlist_head head;
1415 struct rcu_head rcu;
1416};
1417
1418/* - pseudo header */
1419struct tcp4_pseudohdr {
1420 __be32 saddr;
1421 __be32 daddr;
1422 __u8 pad;
1423 __u8 protocol;
1424 __be16 len;
1425};
1426
1427struct tcp6_pseudohdr {
1428 struct in6_addr saddr;
1429 struct in6_addr daddr;
1430 __be32 len;
1431 __be32 protocol; /* including padding */
1432};
1433
1434union tcp_md5sum_block {
1435 struct tcp4_pseudohdr ip4;
1436#if IS_ENABLED(CONFIG_IPV6)
1437 struct tcp6_pseudohdr ip6;
1438#endif
1439};
1440
1441/* - pool: digest algorithm, hash description and scratch buffer */
1442struct tcp_md5sig_pool {
1443 struct ahash_request *md5_req;
1444 void *scratch;
1445};
1446
1447/* - functions */
1448int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1449 const struct sock *sk, const struct sk_buff *skb);
1450int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1451 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1452int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1453 int family);
1454struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1455 const struct sock *addr_sk);
1456
1457#ifdef CONFIG_TCP_MD5SIG
1458struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1459 const union tcp_md5_addr *addr,
1460 int family);
1461#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1462#else
1463static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1464 const union tcp_md5_addr *addr,
1465 int family)
1466{
1467 return NULL;
1468}
1469#define tcp_twsk_md5_key(twsk) NULL
1470#endif
1471
1472bool tcp_alloc_md5sig_pool(void);
1473
1474struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1475static inline void tcp_put_md5sig_pool(void)
1476{
1477 local_bh_enable();
1478}
1479
1480int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1481 unsigned int header_len);
1482int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1483 const struct tcp_md5sig_key *key);
1484
1485/* From tcp_fastopen.c */
1486void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1487 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1488 unsigned long *last_syn_loss);
1489void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1490 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1491 u16 try_exp);
1492struct tcp_fastopen_request {
1493 /* Fast Open cookie. Size 0 means a cookie request */
1494 struct tcp_fastopen_cookie cookie;
1495 struct msghdr *data; /* data in MSG_FASTOPEN */
1496 size_t size;
1497 int copied; /* queued in tcp_connect() */
1498};
1499void tcp_free_fastopen_req(struct tcp_sock *tp);
1500
1501extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1502int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1503void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1504struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1505 struct request_sock *req,
1506 struct tcp_fastopen_cookie *foc,
1507 struct dst_entry *dst);
1508void tcp_fastopen_init_key_once(bool publish);
1509#define TCP_FASTOPEN_KEY_LENGTH 16
1510
1511/* Fastopen key context */
1512struct tcp_fastopen_context {
1513 struct crypto_cipher *tfm;
1514 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1515 struct rcu_head rcu;
1516};
1517
1518/* Latencies incurred by various limits for a sender. They are
1519 * chronograph-like stats that are mutually exclusive.
1520 */
1521enum tcp_chrono {
1522 TCP_CHRONO_UNSPEC,
1523 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1524 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1525 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1526 __TCP_CHRONO_MAX,
1527};
1528
1529void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1530void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1531
1532/* write queue abstraction */
1533static inline void tcp_write_queue_purge(struct sock *sk)
1534{
1535 struct sk_buff *skb;
1536
1537 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1538 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1539 sk_wmem_free_skb(sk, skb);
1540 sk_mem_reclaim(sk);
1541 tcp_clear_all_retrans_hints(tcp_sk(sk));
1542}
1543
1544static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1545{
1546 return skb_peek(&sk->sk_write_queue);
1547}
1548
1549static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1550{
1551 return skb_peek_tail(&sk->sk_write_queue);
1552}
1553
1554static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1555 const struct sk_buff *skb)
1556{
1557 return skb_queue_next(&sk->sk_write_queue, skb);
1558}
1559
1560static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1561 const struct sk_buff *skb)
1562{
1563 return skb_queue_prev(&sk->sk_write_queue, skb);
1564}
1565
1566#define tcp_for_write_queue(skb, sk) \
1567 skb_queue_walk(&(sk)->sk_write_queue, skb)
1568
1569#define tcp_for_write_queue_from(skb, sk) \
1570 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1571
1572#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1573 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1574
1575static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1576{
1577 return sk->sk_send_head;
1578}
1579
1580static inline bool tcp_skb_is_last(const struct sock *sk,
1581 const struct sk_buff *skb)
1582{
1583 return skb_queue_is_last(&sk->sk_write_queue, skb);
1584}
1585
1586static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1587{
1588 if (tcp_skb_is_last(sk, skb))
1589 sk->sk_send_head = NULL;
1590 else
1591 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1592}
1593
1594static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1595{
1596 if (sk->sk_send_head == skb_unlinked) {
1597 sk->sk_send_head = NULL;
1598 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1599 }
1600 if (tcp_sk(sk)->highest_sack == skb_unlinked)
1601 tcp_sk(sk)->highest_sack = NULL;
1602}
1603
1604static inline void tcp_init_send_head(struct sock *sk)
1605{
1606 sk->sk_send_head = NULL;
1607}
1608
1609static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1610{
1611 __skb_queue_tail(&sk->sk_write_queue, skb);
1612}
1613
1614static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1615{
1616 __tcp_add_write_queue_tail(sk, skb);
1617
1618 /* Queue it, remembering where we must start sending. */
1619 if (sk->sk_send_head == NULL) {
1620 sk->sk_send_head = skb;
1621 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1622
1623 if (tcp_sk(sk)->highest_sack == NULL)
1624 tcp_sk(sk)->highest_sack = skb;
1625 }
1626}
1627
1628static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1629{
1630 __skb_queue_head(&sk->sk_write_queue, skb);
1631}
1632
1633/* Insert buff after skb on the write queue of sk. */
1634static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1635 struct sk_buff *buff,
1636 struct sock *sk)
1637{
1638 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1639}
1640
1641/* Insert new before skb on the write queue of sk. */
1642static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1643 struct sk_buff *skb,
1644 struct sock *sk)
1645{
1646 __skb_queue_before(&sk->sk_write_queue, skb, new);
1647
1648 if (sk->sk_send_head == skb)
1649 sk->sk_send_head = new;
1650}
1651
1652static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1653{
1654 __skb_unlink(skb, &sk->sk_write_queue);
1655}
1656
1657static inline bool tcp_write_queue_empty(struct sock *sk)
1658{
1659 return skb_queue_empty(&sk->sk_write_queue);
1660}
1661
1662static inline void tcp_push_pending_frames(struct sock *sk)
1663{
1664 if (tcp_send_head(sk)) {
1665 struct tcp_sock *tp = tcp_sk(sk);
1666
1667 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1668 }
1669}
1670
1671/* Start sequence of the skb just after the highest skb with SACKed
1672 * bit, valid only if sacked_out > 0 or when the caller has ensured
1673 * validity by itself.
1674 */
1675static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1676{
1677 if (!tp->sacked_out)
1678 return tp->snd_una;
1679
1680 if (tp->highest_sack == NULL)
1681 return tp->snd_nxt;
1682
1683 return TCP_SKB_CB(tp->highest_sack)->seq;
1684}
1685
1686static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1687{
1688 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1689 tcp_write_queue_next(sk, skb);
1690}
1691
1692static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1693{
1694 return tcp_sk(sk)->highest_sack;
1695}
1696
1697static inline void tcp_highest_sack_reset(struct sock *sk)
1698{
1699 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1700}
1701
1702/* Called when old skb is about to be deleted (to be combined with new skb) */
1703static inline void tcp_highest_sack_combine(struct sock *sk,
1704 struct sk_buff *old,
1705 struct sk_buff *new)
1706{
1707 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1708 tcp_sk(sk)->highest_sack = new;
1709}
1710
1711/* This helper checks if socket has IP_TRANSPARENT set */
1712static inline bool inet_sk_transparent(const struct sock *sk)
1713{
1714 switch (sk->sk_state) {
1715 case TCP_TIME_WAIT:
1716 return inet_twsk(sk)->tw_transparent;
1717 case TCP_NEW_SYN_RECV:
1718 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1719 }
1720 return inet_sk(sk)->transparent;
1721}
1722
1723/* Determines whether this is a thin stream (which may suffer from
1724 * increased latency). Used to trigger latency-reducing mechanisms.
1725 */
1726static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1727{
1728 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1729}
1730
1731/* /proc */
1732enum tcp_seq_states {
1733 TCP_SEQ_STATE_LISTENING,
1734 TCP_SEQ_STATE_ESTABLISHED,
1735};
1736
1737int tcp_seq_open(struct inode *inode, struct file *file);
1738
1739struct tcp_seq_afinfo {
1740 char *name;
1741 sa_family_t family;
1742 const struct file_operations *seq_fops;
1743 struct seq_operations seq_ops;
1744};
1745
1746struct tcp_iter_state {
1747 struct seq_net_private p;
1748 sa_family_t family;
1749 enum tcp_seq_states state;
1750 struct sock *syn_wait_sk;
1751 int bucket, offset, sbucket, num;
1752 loff_t last_pos;
1753};
1754
1755int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1756void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1757
1758extern struct request_sock_ops tcp_request_sock_ops;
1759extern struct request_sock_ops tcp6_request_sock_ops;
1760
1761void tcp_v4_destroy_sock(struct sock *sk);
1762
1763struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1764 netdev_features_t features);
1765struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1766int tcp_gro_complete(struct sk_buff *skb);
1767
1768void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1769
1770static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1771{
1772 struct net *net = sock_net((struct sock *)tp);
1773 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1774}
1775
1776static inline bool tcp_stream_memory_free(const struct sock *sk)
1777{
1778 const struct tcp_sock *tp = tcp_sk(sk);
1779 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1780
1781 return notsent_bytes < tcp_notsent_lowat(tp);
1782}
1783
1784#ifdef CONFIG_PROC_FS
1785int tcp4_proc_init(void);
1786void tcp4_proc_exit(void);
1787#endif
1788
1789int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1790int tcp_conn_request(struct request_sock_ops *rsk_ops,
1791 const struct tcp_request_sock_ops *af_ops,
1792 struct sock *sk, struct sk_buff *skb);
1793
1794/* TCP af-specific functions */
1795struct tcp_sock_af_ops {
1796#ifdef CONFIG_TCP_MD5SIG
1797 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1798 const struct sock *addr_sk);
1799 int (*calc_md5_hash)(char *location,
1800 const struct tcp_md5sig_key *md5,
1801 const struct sock *sk,
1802 const struct sk_buff *skb);
1803 int (*md5_parse)(struct sock *sk,
1804 char __user *optval,
1805 int optlen);
1806#endif
1807};
1808
1809struct tcp_request_sock_ops {
1810 u16 mss_clamp;
1811#ifdef CONFIG_TCP_MD5SIG
1812 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1813 const struct sock *addr_sk);
1814 int (*calc_md5_hash) (char *location,
1815 const struct tcp_md5sig_key *md5,
1816 const struct sock *sk,
1817 const struct sk_buff *skb);
1818#endif
1819 void (*init_req)(struct request_sock *req,
1820 const struct sock *sk_listener,
1821 struct sk_buff *skb);
1822#ifdef CONFIG_SYN_COOKIES
1823 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1824 __u16 *mss);
1825#endif
1826 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1827 const struct request_sock *req,
1828 bool *strict);
1829 __u32 (*init_seq)(const struct sk_buff *skb, u32 *tsoff);
1830 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1831 struct flowi *fl, struct request_sock *req,
1832 struct tcp_fastopen_cookie *foc,
1833 enum tcp_synack_type synack_type);
1834};
1835
1836#ifdef CONFIG_SYN_COOKIES
1837static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1838 const struct sock *sk, struct sk_buff *skb,
1839 __u16 *mss)
1840{
1841 tcp_synq_overflow(sk);
1842 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1843 return ops->cookie_init_seq(skb, mss);
1844}
1845#else
1846static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1847 const struct sock *sk, struct sk_buff *skb,
1848 __u16 *mss)
1849{
1850 return 0;
1851}
1852#endif
1853
1854int tcpv4_offload_init(void);
1855
1856void tcp_v4_init(void);
1857void tcp_init(void);
1858
1859/* tcp_recovery.c */
1860
1861/* Flags to enable various loss recovery features. See below */
1862extern int sysctl_tcp_recovery;
1863
1864/* Use TCP RACK to detect (some) tail and retransmit losses */
1865#define TCP_RACK_LOST_RETRANS 0x1
1866
1867extern int tcp_rack_mark_lost(struct sock *sk);
1868
1869extern void tcp_rack_advance(struct tcp_sock *tp,
1870 const struct skb_mstamp *xmit_time, u8 sacked);
1871
1872/*
1873 * Save and compile IPv4 options, return a pointer to it
1874 */
1875static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
1876{
1877 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1878 struct ip_options_rcu *dopt = NULL;
1879
1880 if (opt->optlen) {
1881 int opt_size = sizeof(*dopt) + opt->optlen;
1882
1883 dopt = kmalloc(opt_size, GFP_ATOMIC);
1884 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
1885 kfree(dopt);
1886 dopt = NULL;
1887 }
1888 }
1889 return dopt;
1890}
1891
1892/* locally generated TCP pure ACKs have skb->truesize == 2
1893 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1894 * This is much faster than dissecting the packet to find out.
1895 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1896 */
1897static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1898{
1899 return skb->truesize == 2;
1900}
1901
1902static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1903{
1904 skb->truesize = 2;
1905}
1906
1907static inline int tcp_inq(struct sock *sk)
1908{
1909 struct tcp_sock *tp = tcp_sk(sk);
1910 int answ;
1911
1912 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1913 answ = 0;
1914 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1915 !tp->urg_data ||
1916 before(tp->urg_seq, tp->copied_seq) ||
1917 !before(tp->urg_seq, tp->rcv_nxt)) {
1918
1919 answ = tp->rcv_nxt - tp->copied_seq;
1920
1921 /* Subtract 1, if FIN was received */
1922 if (answ && sock_flag(sk, SOCK_DONE))
1923 answ--;
1924 } else {
1925 answ = tp->urg_seq - tp->copied_seq;
1926 }
1927
1928 return answ;
1929}
1930
1931int tcp_peek_len(struct socket *sock);
1932
1933static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1934{
1935 u16 segs_in;
1936
1937 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1938 tp->segs_in += segs_in;
1939 if (skb->len > tcp_hdrlen(skb))
1940 tp->data_segs_in += segs_in;
1941}
1942
1943/*
1944 * TCP listen path runs lockless.
1945 * We forced "struct sock" to be const qualified to make sure
1946 * we don't modify one of its field by mistake.
1947 * Here, we increment sk_drops which is an atomic_t, so we can safely
1948 * make sock writable again.
1949 */
1950static inline void tcp_listendrop(const struct sock *sk)
1951{
1952 atomic_inc(&((struct sock *)sk)->sk_drops);
1953 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
1954}
1955
1956#endif /* _TCP_H */