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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/cryptohash.h>
27#include <linux/kref.h>
28#include <linux/ktime.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
43#include <linux/seq_file.h>
44#include <linux/memcontrol.h>
45#include <linux/bpf-cgroup.h>
46#include <linux/siphash.h>
47
48extern struct inet_hashinfo tcp_hashinfo;
49
50extern struct percpu_counter tcp_orphan_count;
51void tcp_time_wait(struct sock *sk, int state, int timeo);
52
53#define MAX_TCP_HEADER (128 + MAX_HEADER)
54#define MAX_TCP_OPTION_SPACE 40
55#define TCP_MIN_SND_MSS 48
56#define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
57
58/*
59 * Never offer a window over 32767 without using window scaling. Some
60 * poor stacks do signed 16bit maths!
61 */
62#define MAX_TCP_WINDOW 32767U
63
64/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
65#define TCP_MIN_MSS 88U
66
67/* The initial MTU to use for probing */
68#define TCP_BASE_MSS 1024
69
70/* probing interval, default to 10 minutes as per RFC4821 */
71#define TCP_PROBE_INTERVAL 600
72
73/* Specify interval when tcp mtu probing will stop */
74#define TCP_PROBE_THRESHOLD 8
75
76/* After receiving this amount of duplicate ACKs fast retransmit starts. */
77#define TCP_FASTRETRANS_THRESH 3
78
79/* Maximal number of ACKs sent quickly to accelerate slow-start. */
80#define TCP_MAX_QUICKACKS 16U
81
82/* Maximal number of window scale according to RFC1323 */
83#define TCP_MAX_WSCALE 14U
84
85/* urg_data states */
86#define TCP_URG_VALID 0x0100
87#define TCP_URG_NOTYET 0x0200
88#define TCP_URG_READ 0x0400
89
90#define TCP_RETR1 3 /*
91 * This is how many retries it does before it
92 * tries to figure out if the gateway is
93 * down. Minimal RFC value is 3; it corresponds
94 * to ~3sec-8min depending on RTO.
95 */
96
97#define TCP_RETR2 15 /*
98 * This should take at least
99 * 90 minutes to time out.
100 * RFC1122 says that the limit is 100 sec.
101 * 15 is ~13-30min depending on RTO.
102 */
103
104#define TCP_SYN_RETRIES 6 /* This is how many retries are done
105 * when active opening a connection.
106 * RFC1122 says the minimum retry MUST
107 * be at least 180secs. Nevertheless
108 * this value is corresponding to
109 * 63secs of retransmission with the
110 * current initial RTO.
111 */
112
113#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
114 * when passive opening a connection.
115 * This is corresponding to 31secs of
116 * retransmission with the current
117 * initial RTO.
118 */
119
120#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
121 * state, about 60 seconds */
122#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
123 /* BSD style FIN_WAIT2 deadlock breaker.
124 * It used to be 3min, new value is 60sec,
125 * to combine FIN-WAIT-2 timeout with
126 * TIME-WAIT timer.
127 */
128
129#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
130#if HZ >= 100
131#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
132#define TCP_ATO_MIN ((unsigned)(HZ/25))
133#else
134#define TCP_DELACK_MIN 4U
135#define TCP_ATO_MIN 4U
136#endif
137#define TCP_RTO_MAX ((unsigned)(120*HZ))
138#define TCP_RTO_MIN ((unsigned)(HZ/5))
139#define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
140#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
141#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
142 * used as a fallback RTO for the
143 * initial data transmission if no
144 * valid RTT sample has been acquired,
145 * most likely due to retrans in 3WHS.
146 */
147
148#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
149 * for local resources.
150 */
151#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
152#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
153#define TCP_KEEPALIVE_INTVL (75*HZ)
154
155#define MAX_TCP_KEEPIDLE 32767
156#define MAX_TCP_KEEPINTVL 32767
157#define MAX_TCP_KEEPCNT 127
158#define MAX_TCP_SYNCNT 127
159
160#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
161
162#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
163#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
164 * after this time. It should be equal
165 * (or greater than) TCP_TIMEWAIT_LEN
166 * to provide reliability equal to one
167 * provided by timewait state.
168 */
169#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
170 * timestamps. It must be less than
171 * minimal timewait lifetime.
172 */
173/*
174 * TCP option
175 */
176
177#define TCPOPT_NOP 1 /* Padding */
178#define TCPOPT_EOL 0 /* End of options */
179#define TCPOPT_MSS 2 /* Segment size negotiating */
180#define TCPOPT_WINDOW 3 /* Window scaling */
181#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
182#define TCPOPT_SACK 5 /* SACK Block */
183#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
184#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
185#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
186#define TCPOPT_EXP 254 /* Experimental */
187/* Magic number to be after the option value for sharing TCP
188 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
189 */
190#define TCPOPT_FASTOPEN_MAGIC 0xF989
191#define TCPOPT_SMC_MAGIC 0xE2D4C3D9
192
193/*
194 * TCP option lengths
195 */
196
197#define TCPOLEN_MSS 4
198#define TCPOLEN_WINDOW 3
199#define TCPOLEN_SACK_PERM 2
200#define TCPOLEN_TIMESTAMP 10
201#define TCPOLEN_MD5SIG 18
202#define TCPOLEN_FASTOPEN_BASE 2
203#define TCPOLEN_EXP_FASTOPEN_BASE 4
204#define TCPOLEN_EXP_SMC_BASE 6
205
206/* But this is what stacks really send out. */
207#define TCPOLEN_TSTAMP_ALIGNED 12
208#define TCPOLEN_WSCALE_ALIGNED 4
209#define TCPOLEN_SACKPERM_ALIGNED 4
210#define TCPOLEN_SACK_BASE 2
211#define TCPOLEN_SACK_BASE_ALIGNED 4
212#define TCPOLEN_SACK_PERBLOCK 8
213#define TCPOLEN_MD5SIG_ALIGNED 20
214#define TCPOLEN_MSS_ALIGNED 4
215#define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
216
217/* Flags in tp->nonagle */
218#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
219#define TCP_NAGLE_CORK 2 /* Socket is corked */
220#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
221
222/* TCP thin-stream limits */
223#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
224
225/* TCP initial congestion window as per rfc6928 */
226#define TCP_INIT_CWND 10
227
228/* Bit Flags for sysctl_tcp_fastopen */
229#define TFO_CLIENT_ENABLE 1
230#define TFO_SERVER_ENABLE 2
231#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
232
233/* Accept SYN data w/o any cookie option */
234#define TFO_SERVER_COOKIE_NOT_REQD 0x200
235
236/* Force enable TFO on all listeners, i.e., not requiring the
237 * TCP_FASTOPEN socket option.
238 */
239#define TFO_SERVER_WO_SOCKOPT1 0x400
240
241
242/* sysctl variables for tcp */
243extern int sysctl_tcp_max_orphans;
244extern long sysctl_tcp_mem[3];
245
246#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
247#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
248#define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
249
250extern atomic_long_t tcp_memory_allocated;
251extern struct percpu_counter tcp_sockets_allocated;
252extern unsigned long tcp_memory_pressure;
253
254/* optimized version of sk_under_memory_pressure() for TCP sockets */
255static inline bool tcp_under_memory_pressure(const struct sock *sk)
256{
257 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
258 mem_cgroup_under_socket_pressure(sk->sk_memcg))
259 return true;
260
261 return READ_ONCE(tcp_memory_pressure);
262}
263/*
264 * The next routines deal with comparing 32 bit unsigned ints
265 * and worry about wraparound (automatic with unsigned arithmetic).
266 */
267
268static inline bool before(__u32 seq1, __u32 seq2)
269{
270 return (__s32)(seq1-seq2) < 0;
271}
272#define after(seq2, seq1) before(seq1, seq2)
273
274/* is s2<=s1<=s3 ? */
275static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
276{
277 return seq3 - seq2 >= seq1 - seq2;
278}
279
280static inline bool tcp_out_of_memory(struct sock *sk)
281{
282 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
283 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
284 return true;
285 return false;
286}
287
288void sk_forced_mem_schedule(struct sock *sk, int size);
289
290static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
291{
292 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
293 int orphans = percpu_counter_read_positive(ocp);
294
295 if (orphans << shift > sysctl_tcp_max_orphans) {
296 orphans = percpu_counter_sum_positive(ocp);
297 if (orphans << shift > sysctl_tcp_max_orphans)
298 return true;
299 }
300 return false;
301}
302
303bool tcp_check_oom(struct sock *sk, int shift);
304
305
306extern struct proto tcp_prot;
307
308#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
309#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
311#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
312
313void tcp_tasklet_init(void);
314
315int tcp_v4_err(struct sk_buff *skb, u32);
316
317void tcp_shutdown(struct sock *sk, int how);
318
319int tcp_v4_early_demux(struct sk_buff *skb);
320int tcp_v4_rcv(struct sk_buff *skb);
321
322int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
323int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
324int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
325int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
326 int flags);
327int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
328 size_t size, int flags);
329ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
330 size_t size, int flags);
331void tcp_release_cb(struct sock *sk);
332void tcp_wfree(struct sk_buff *skb);
333void tcp_write_timer_handler(struct sock *sk);
334void tcp_delack_timer_handler(struct sock *sk);
335int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
336int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
337void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
338void tcp_rcv_space_adjust(struct sock *sk);
339int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
340void tcp_twsk_destructor(struct sock *sk);
341ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
342 struct pipe_inode_info *pipe, size_t len,
343 unsigned int flags);
344
345void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
346static inline void tcp_dec_quickack_mode(struct sock *sk,
347 const unsigned int pkts)
348{
349 struct inet_connection_sock *icsk = inet_csk(sk);
350
351 if (icsk->icsk_ack.quick) {
352 if (pkts >= icsk->icsk_ack.quick) {
353 icsk->icsk_ack.quick = 0;
354 /* Leaving quickack mode we deflate ATO. */
355 icsk->icsk_ack.ato = TCP_ATO_MIN;
356 } else
357 icsk->icsk_ack.quick -= pkts;
358 }
359}
360
361#define TCP_ECN_OK 1
362#define TCP_ECN_QUEUE_CWR 2
363#define TCP_ECN_DEMAND_CWR 4
364#define TCP_ECN_SEEN 8
365
366enum tcp_tw_status {
367 TCP_TW_SUCCESS = 0,
368 TCP_TW_RST = 1,
369 TCP_TW_ACK = 2,
370 TCP_TW_SYN = 3
371};
372
373
374enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
375 struct sk_buff *skb,
376 const struct tcphdr *th);
377struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
378 struct request_sock *req, bool fastopen,
379 bool *lost_race);
380int tcp_child_process(struct sock *parent, struct sock *child,
381 struct sk_buff *skb);
382void tcp_enter_loss(struct sock *sk);
383void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
384void tcp_clear_retrans(struct tcp_sock *tp);
385void tcp_update_metrics(struct sock *sk);
386void tcp_init_metrics(struct sock *sk);
387void tcp_metrics_init(void);
388bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
389void tcp_close(struct sock *sk, long timeout);
390void tcp_init_sock(struct sock *sk);
391void tcp_init_transfer(struct sock *sk, int bpf_op);
392__poll_t tcp_poll(struct file *file, struct socket *sock,
393 struct poll_table_struct *wait);
394int tcp_getsockopt(struct sock *sk, int level, int optname,
395 char __user *optval, int __user *optlen);
396int tcp_setsockopt(struct sock *sk, int level, int optname,
397 char __user *optval, unsigned int optlen);
398int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
399 char __user *optval, int __user *optlen);
400int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
401 char __user *optval, unsigned int optlen);
402void tcp_set_keepalive(struct sock *sk, int val);
403void tcp_syn_ack_timeout(const struct request_sock *req);
404int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
405 int flags, int *addr_len);
406int tcp_set_rcvlowat(struct sock *sk, int val);
407void tcp_data_ready(struct sock *sk);
408#ifdef CONFIG_MMU
409int tcp_mmap(struct file *file, struct socket *sock,
410 struct vm_area_struct *vma);
411#endif
412void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
413 struct tcp_options_received *opt_rx,
414 int estab, struct tcp_fastopen_cookie *foc);
415const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
416
417/*
418 * BPF SKB-less helpers
419 */
420u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
421 struct tcphdr *th, u32 *cookie);
422u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
423 struct tcphdr *th, u32 *cookie);
424u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
425 const struct tcp_request_sock_ops *af_ops,
426 struct sock *sk, struct tcphdr *th);
427/*
428 * TCP v4 functions exported for the inet6 API
429 */
430
431void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
432void tcp_v4_mtu_reduced(struct sock *sk);
433void tcp_req_err(struct sock *sk, u32 seq, bool abort);
434int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
435struct sock *tcp_create_openreq_child(const struct sock *sk,
436 struct request_sock *req,
437 struct sk_buff *skb);
438void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
439struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
440 struct request_sock *req,
441 struct dst_entry *dst,
442 struct request_sock *req_unhash,
443 bool *own_req);
444int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
445int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
446int tcp_connect(struct sock *sk);
447enum tcp_synack_type {
448 TCP_SYNACK_NORMAL,
449 TCP_SYNACK_FASTOPEN,
450 TCP_SYNACK_COOKIE,
451};
452struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
453 struct request_sock *req,
454 struct tcp_fastopen_cookie *foc,
455 enum tcp_synack_type synack_type);
456int tcp_disconnect(struct sock *sk, int flags);
457
458void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
459int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
460void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
461
462/* From syncookies.c */
463struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
464 struct request_sock *req,
465 struct dst_entry *dst, u32 tsoff);
466int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
467 u32 cookie);
468struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
469#ifdef CONFIG_SYN_COOKIES
470
471/* Syncookies use a monotonic timer which increments every 60 seconds.
472 * This counter is used both as a hash input and partially encoded into
473 * the cookie value. A cookie is only validated further if the delta
474 * between the current counter value and the encoded one is less than this,
475 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
476 * the counter advances immediately after a cookie is generated).
477 */
478#define MAX_SYNCOOKIE_AGE 2
479#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
480#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
481
482/* syncookies: remember time of last synqueue overflow
483 * But do not dirty this field too often (once per second is enough)
484 * It is racy as we do not hold a lock, but race is very minor.
485 */
486static inline void tcp_synq_overflow(const struct sock *sk)
487{
488 unsigned int last_overflow;
489 unsigned int now = jiffies;
490
491 if (sk->sk_reuseport) {
492 struct sock_reuseport *reuse;
493
494 reuse = rcu_dereference(sk->sk_reuseport_cb);
495 if (likely(reuse)) {
496 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
497 if (time_after32(now, last_overflow + HZ))
498 WRITE_ONCE(reuse->synq_overflow_ts, now);
499 return;
500 }
501 }
502
503 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
504 if (time_after32(now, last_overflow + HZ))
505 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
506}
507
508/* syncookies: no recent synqueue overflow on this listening socket? */
509static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
510{
511 unsigned int last_overflow;
512 unsigned int now = jiffies;
513
514 if (sk->sk_reuseport) {
515 struct sock_reuseport *reuse;
516
517 reuse = rcu_dereference(sk->sk_reuseport_cb);
518 if (likely(reuse)) {
519 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
520 return time_after32(now, last_overflow +
521 TCP_SYNCOOKIE_VALID);
522 }
523 }
524
525 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
526 return time_after32(now, last_overflow + TCP_SYNCOOKIE_VALID);
527}
528
529static inline u32 tcp_cookie_time(void)
530{
531 u64 val = get_jiffies_64();
532
533 do_div(val, TCP_SYNCOOKIE_PERIOD);
534 return val;
535}
536
537u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
538 u16 *mssp);
539__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
540u64 cookie_init_timestamp(struct request_sock *req);
541bool cookie_timestamp_decode(const struct net *net,
542 struct tcp_options_received *opt);
543bool cookie_ecn_ok(const struct tcp_options_received *opt,
544 const struct net *net, const struct dst_entry *dst);
545
546/* From net/ipv6/syncookies.c */
547int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
548 u32 cookie);
549struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
550
551u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
552 const struct tcphdr *th, u16 *mssp);
553__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
554#endif
555/* tcp_output.c */
556
557void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
558 int nonagle);
559int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
560int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
561void tcp_retransmit_timer(struct sock *sk);
562void tcp_xmit_retransmit_queue(struct sock *);
563void tcp_simple_retransmit(struct sock *);
564void tcp_enter_recovery(struct sock *sk, bool ece_ack);
565int tcp_trim_head(struct sock *, struct sk_buff *, u32);
566enum tcp_queue {
567 TCP_FRAG_IN_WRITE_QUEUE,
568 TCP_FRAG_IN_RTX_QUEUE,
569};
570int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
571 struct sk_buff *skb, u32 len,
572 unsigned int mss_now, gfp_t gfp);
573
574void tcp_send_probe0(struct sock *);
575void tcp_send_partial(struct sock *);
576int tcp_write_wakeup(struct sock *, int mib);
577void tcp_send_fin(struct sock *sk);
578void tcp_send_active_reset(struct sock *sk, gfp_t priority);
579int tcp_send_synack(struct sock *);
580void tcp_push_one(struct sock *, unsigned int mss_now);
581void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
582void tcp_send_ack(struct sock *sk);
583void tcp_send_delayed_ack(struct sock *sk);
584void tcp_send_loss_probe(struct sock *sk);
585bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
586void tcp_skb_collapse_tstamp(struct sk_buff *skb,
587 const struct sk_buff *next_skb);
588
589/* tcp_input.c */
590void tcp_rearm_rto(struct sock *sk);
591void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
592void tcp_reset(struct sock *sk);
593void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
594void tcp_fin(struct sock *sk);
595
596/* tcp_timer.c */
597void tcp_init_xmit_timers(struct sock *);
598static inline void tcp_clear_xmit_timers(struct sock *sk)
599{
600 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
601 __sock_put(sk);
602
603 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
604 __sock_put(sk);
605
606 inet_csk_clear_xmit_timers(sk);
607}
608
609unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
610unsigned int tcp_current_mss(struct sock *sk);
611
612/* Bound MSS / TSO packet size with the half of the window */
613static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
614{
615 int cutoff;
616
617 /* When peer uses tiny windows, there is no use in packetizing
618 * to sub-MSS pieces for the sake of SWS or making sure there
619 * are enough packets in the pipe for fast recovery.
620 *
621 * On the other hand, for extremely large MSS devices, handling
622 * smaller than MSS windows in this way does make sense.
623 */
624 if (tp->max_window > TCP_MSS_DEFAULT)
625 cutoff = (tp->max_window >> 1);
626 else
627 cutoff = tp->max_window;
628
629 if (cutoff && pktsize > cutoff)
630 return max_t(int, cutoff, 68U - tp->tcp_header_len);
631 else
632 return pktsize;
633}
634
635/* tcp.c */
636void tcp_get_info(struct sock *, struct tcp_info *);
637
638/* Read 'sendfile()'-style from a TCP socket */
639int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
640 sk_read_actor_t recv_actor);
641
642void tcp_initialize_rcv_mss(struct sock *sk);
643
644int tcp_mtu_to_mss(struct sock *sk, int pmtu);
645int tcp_mss_to_mtu(struct sock *sk, int mss);
646void tcp_mtup_init(struct sock *sk);
647void tcp_init_buffer_space(struct sock *sk);
648
649static inline void tcp_bound_rto(const struct sock *sk)
650{
651 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
652 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
653}
654
655static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
656{
657 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
658}
659
660static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
661{
662 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
663 ntohl(TCP_FLAG_ACK) |
664 snd_wnd);
665}
666
667static inline void tcp_fast_path_on(struct tcp_sock *tp)
668{
669 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
670}
671
672static inline void tcp_fast_path_check(struct sock *sk)
673{
674 struct tcp_sock *tp = tcp_sk(sk);
675
676 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
677 tp->rcv_wnd &&
678 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
679 !tp->urg_data)
680 tcp_fast_path_on(tp);
681}
682
683/* Compute the actual rto_min value */
684static inline u32 tcp_rto_min(struct sock *sk)
685{
686 const struct dst_entry *dst = __sk_dst_get(sk);
687 u32 rto_min = TCP_RTO_MIN;
688
689 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
690 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
691 return rto_min;
692}
693
694static inline u32 tcp_rto_min_us(struct sock *sk)
695{
696 return jiffies_to_usecs(tcp_rto_min(sk));
697}
698
699static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
700{
701 return dst_metric_locked(dst, RTAX_CC_ALGO);
702}
703
704/* Minimum RTT in usec. ~0 means not available. */
705static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
706{
707 return minmax_get(&tp->rtt_min);
708}
709
710/* Compute the actual receive window we are currently advertising.
711 * Rcv_nxt can be after the window if our peer push more data
712 * than the offered window.
713 */
714static inline u32 tcp_receive_window(const struct tcp_sock *tp)
715{
716 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
717
718 if (win < 0)
719 win = 0;
720 return (u32) win;
721}
722
723/* Choose a new window, without checks for shrinking, and without
724 * scaling applied to the result. The caller does these things
725 * if necessary. This is a "raw" window selection.
726 */
727u32 __tcp_select_window(struct sock *sk);
728
729void tcp_send_window_probe(struct sock *sk);
730
731/* TCP uses 32bit jiffies to save some space.
732 * Note that this is different from tcp_time_stamp, which
733 * historically has been the same until linux-4.13.
734 */
735#define tcp_jiffies32 ((u32)jiffies)
736
737/*
738 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
739 * It is no longer tied to jiffies, but to 1 ms clock.
740 * Note: double check if you want to use tcp_jiffies32 instead of this.
741 */
742#define TCP_TS_HZ 1000
743
744static inline u64 tcp_clock_ns(void)
745{
746 return ktime_get_ns();
747}
748
749static inline u64 tcp_clock_us(void)
750{
751 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
752}
753
754/* This should only be used in contexts where tp->tcp_mstamp is up to date */
755static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
756{
757 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
758}
759
760/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
761static inline u32 tcp_time_stamp_raw(void)
762{
763 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
764}
765
766void tcp_mstamp_refresh(struct tcp_sock *tp);
767
768static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
769{
770 return max_t(s64, t1 - t0, 0);
771}
772
773static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
774{
775 return div_u64(skb->skb_mstamp_ns, NSEC_PER_SEC / TCP_TS_HZ);
776}
777
778/* provide the departure time in us unit */
779static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
780{
781 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
782}
783
784
785#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
786
787#define TCPHDR_FIN 0x01
788#define TCPHDR_SYN 0x02
789#define TCPHDR_RST 0x04
790#define TCPHDR_PSH 0x08
791#define TCPHDR_ACK 0x10
792#define TCPHDR_URG 0x20
793#define TCPHDR_ECE 0x40
794#define TCPHDR_CWR 0x80
795
796#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
797
798/* This is what the send packet queuing engine uses to pass
799 * TCP per-packet control information to the transmission code.
800 * We also store the host-order sequence numbers in here too.
801 * This is 44 bytes if IPV6 is enabled.
802 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
803 */
804struct tcp_skb_cb {
805 __u32 seq; /* Starting sequence number */
806 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
807 union {
808 /* Note : tcp_tw_isn is used in input path only
809 * (isn chosen by tcp_timewait_state_process())
810 *
811 * tcp_gso_segs/size are used in write queue only,
812 * cf tcp_skb_pcount()/tcp_skb_mss()
813 */
814 __u32 tcp_tw_isn;
815 struct {
816 u16 tcp_gso_segs;
817 u16 tcp_gso_size;
818 };
819 };
820 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
821
822 __u8 sacked; /* State flags for SACK. */
823#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
824#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
825#define TCPCB_LOST 0x04 /* SKB is lost */
826#define TCPCB_TAGBITS 0x07 /* All tag bits */
827#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */
828#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
829#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
830 TCPCB_REPAIRED)
831
832 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
833 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
834 eor:1, /* Is skb MSG_EOR marked? */
835 has_rxtstamp:1, /* SKB has a RX timestamp */
836 unused:5;
837 __u32 ack_seq; /* Sequence number ACK'd */
838 union {
839 struct {
840 /* There is space for up to 24 bytes */
841 __u32 in_flight:30,/* Bytes in flight at transmit */
842 is_app_limited:1, /* cwnd not fully used? */
843 unused:1;
844 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
845 __u32 delivered;
846 /* start of send pipeline phase */
847 u64 first_tx_mstamp;
848 /* when we reached the "delivered" count */
849 u64 delivered_mstamp;
850 } tx; /* only used for outgoing skbs */
851 union {
852 struct inet_skb_parm h4;
853#if IS_ENABLED(CONFIG_IPV6)
854 struct inet6_skb_parm h6;
855#endif
856 } header; /* For incoming skbs */
857 struct {
858 __u32 flags;
859 struct sock *sk_redir;
860 void *data_end;
861 } bpf;
862 };
863};
864
865#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
866
867static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
868{
869 TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
870}
871
872static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb)
873{
874 return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS;
875}
876
877static inline struct sock *tcp_skb_bpf_redirect_fetch(struct sk_buff *skb)
878{
879 return TCP_SKB_CB(skb)->bpf.sk_redir;
880}
881
882static inline void tcp_skb_bpf_redirect_clear(struct sk_buff *skb)
883{
884 TCP_SKB_CB(skb)->bpf.sk_redir = NULL;
885}
886
887#if IS_ENABLED(CONFIG_IPV6)
888/* This is the variant of inet6_iif() that must be used by TCP,
889 * as TCP moves IP6CB into a different location in skb->cb[]
890 */
891static inline int tcp_v6_iif(const struct sk_buff *skb)
892{
893 return TCP_SKB_CB(skb)->header.h6.iif;
894}
895
896static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
897{
898 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
899
900 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
901}
902
903/* TCP_SKB_CB reference means this can not be used from early demux */
904static inline int tcp_v6_sdif(const struct sk_buff *skb)
905{
906#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
907 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
908 return TCP_SKB_CB(skb)->header.h6.iif;
909#endif
910 return 0;
911}
912#endif
913
914static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
915{
916#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
917 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
918 skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
919 return true;
920#endif
921 return false;
922}
923
924/* TCP_SKB_CB reference means this can not be used from early demux */
925static inline int tcp_v4_sdif(struct sk_buff *skb)
926{
927#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
928 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
929 return TCP_SKB_CB(skb)->header.h4.iif;
930#endif
931 return 0;
932}
933
934/* Due to TSO, an SKB can be composed of multiple actual
935 * packets. To keep these tracked properly, we use this.
936 */
937static inline int tcp_skb_pcount(const struct sk_buff *skb)
938{
939 return TCP_SKB_CB(skb)->tcp_gso_segs;
940}
941
942static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
943{
944 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
945}
946
947static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
948{
949 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
950}
951
952/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
953static inline int tcp_skb_mss(const struct sk_buff *skb)
954{
955 return TCP_SKB_CB(skb)->tcp_gso_size;
956}
957
958static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
959{
960 return likely(!TCP_SKB_CB(skb)->eor);
961}
962
963/* Events passed to congestion control interface */
964enum tcp_ca_event {
965 CA_EVENT_TX_START, /* first transmit when no packets in flight */
966 CA_EVENT_CWND_RESTART, /* congestion window restart */
967 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
968 CA_EVENT_LOSS, /* loss timeout */
969 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
970 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
971};
972
973/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
974enum tcp_ca_ack_event_flags {
975 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
976 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
977 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
978};
979
980/*
981 * Interface for adding new TCP congestion control handlers
982 */
983#define TCP_CA_NAME_MAX 16
984#define TCP_CA_MAX 128
985#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
986
987#define TCP_CA_UNSPEC 0
988
989/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
990#define TCP_CONG_NON_RESTRICTED 0x1
991/* Requires ECN/ECT set on all packets */
992#define TCP_CONG_NEEDS_ECN 0x2
993
994union tcp_cc_info;
995
996struct ack_sample {
997 u32 pkts_acked;
998 s32 rtt_us;
999 u32 in_flight;
1000};
1001
1002/* A rate sample measures the number of (original/retransmitted) data
1003 * packets delivered "delivered" over an interval of time "interval_us".
1004 * The tcp_rate.c code fills in the rate sample, and congestion
1005 * control modules that define a cong_control function to run at the end
1006 * of ACK processing can optionally chose to consult this sample when
1007 * setting cwnd and pacing rate.
1008 * A sample is invalid if "delivered" or "interval_us" is negative.
1009 */
1010struct rate_sample {
1011 u64 prior_mstamp; /* starting timestamp for interval */
1012 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1013 s32 delivered; /* number of packets delivered over interval */
1014 long interval_us; /* time for tp->delivered to incr "delivered" */
1015 u32 snd_interval_us; /* snd interval for delivered packets */
1016 u32 rcv_interval_us; /* rcv interval for delivered packets */
1017 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1018 int losses; /* number of packets marked lost upon ACK */
1019 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1020 u32 prior_in_flight; /* in flight before this ACK */
1021 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1022 bool is_retrans; /* is sample from retransmission? */
1023 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1024};
1025
1026struct tcp_congestion_ops {
1027 struct list_head list;
1028 u32 key;
1029 u32 flags;
1030
1031 /* initialize private data (optional) */
1032 void (*init)(struct sock *sk);
1033 /* cleanup private data (optional) */
1034 void (*release)(struct sock *sk);
1035
1036 /* return slow start threshold (required) */
1037 u32 (*ssthresh)(struct sock *sk);
1038 /* do new cwnd calculation (required) */
1039 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1040 /* call before changing ca_state (optional) */
1041 void (*set_state)(struct sock *sk, u8 new_state);
1042 /* call when cwnd event occurs (optional) */
1043 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1044 /* call when ack arrives (optional) */
1045 void (*in_ack_event)(struct sock *sk, u32 flags);
1046 /* new value of cwnd after loss (required) */
1047 u32 (*undo_cwnd)(struct sock *sk);
1048 /* hook for packet ack accounting (optional) */
1049 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1050 /* override sysctl_tcp_min_tso_segs */
1051 u32 (*min_tso_segs)(struct sock *sk);
1052 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1053 u32 (*sndbuf_expand)(struct sock *sk);
1054 /* call when packets are delivered to update cwnd and pacing rate,
1055 * after all the ca_state processing. (optional)
1056 */
1057 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1058 /* get info for inet_diag (optional) */
1059 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1060 union tcp_cc_info *info);
1061
1062 char name[TCP_CA_NAME_MAX];
1063 struct module *owner;
1064};
1065
1066int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1067void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1068
1069void tcp_assign_congestion_control(struct sock *sk);
1070void tcp_init_congestion_control(struct sock *sk);
1071void tcp_cleanup_congestion_control(struct sock *sk);
1072int tcp_set_default_congestion_control(struct net *net, const char *name);
1073void tcp_get_default_congestion_control(struct net *net, char *name);
1074void tcp_get_available_congestion_control(char *buf, size_t len);
1075void tcp_get_allowed_congestion_control(char *buf, size_t len);
1076int tcp_set_allowed_congestion_control(char *allowed);
1077int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1078 bool reinit, bool cap_net_admin);
1079u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1080void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1081
1082u32 tcp_reno_ssthresh(struct sock *sk);
1083u32 tcp_reno_undo_cwnd(struct sock *sk);
1084void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1085extern struct tcp_congestion_ops tcp_reno;
1086
1087struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1088u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1089#ifdef CONFIG_INET
1090char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1091#else
1092static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1093{
1094 return NULL;
1095}
1096#endif
1097
1098static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1099{
1100 const struct inet_connection_sock *icsk = inet_csk(sk);
1101
1102 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1103}
1104
1105static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1106{
1107 struct inet_connection_sock *icsk = inet_csk(sk);
1108
1109 if (icsk->icsk_ca_ops->set_state)
1110 icsk->icsk_ca_ops->set_state(sk, ca_state);
1111 icsk->icsk_ca_state = ca_state;
1112}
1113
1114static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1115{
1116 const struct inet_connection_sock *icsk = inet_csk(sk);
1117
1118 if (icsk->icsk_ca_ops->cwnd_event)
1119 icsk->icsk_ca_ops->cwnd_event(sk, event);
1120}
1121
1122/* From tcp_rate.c */
1123void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1124void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1125 struct rate_sample *rs);
1126void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1127 bool is_sack_reneg, struct rate_sample *rs);
1128void tcp_rate_check_app_limited(struct sock *sk);
1129
1130/* These functions determine how the current flow behaves in respect of SACK
1131 * handling. SACK is negotiated with the peer, and therefore it can vary
1132 * between different flows.
1133 *
1134 * tcp_is_sack - SACK enabled
1135 * tcp_is_reno - No SACK
1136 */
1137static inline int tcp_is_sack(const struct tcp_sock *tp)
1138{
1139 return likely(tp->rx_opt.sack_ok);
1140}
1141
1142static inline bool tcp_is_reno(const struct tcp_sock *tp)
1143{
1144 return !tcp_is_sack(tp);
1145}
1146
1147static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1148{
1149 return tp->sacked_out + tp->lost_out;
1150}
1151
1152/* This determines how many packets are "in the network" to the best
1153 * of our knowledge. In many cases it is conservative, but where
1154 * detailed information is available from the receiver (via SACK
1155 * blocks etc.) we can make more aggressive calculations.
1156 *
1157 * Use this for decisions involving congestion control, use just
1158 * tp->packets_out to determine if the send queue is empty or not.
1159 *
1160 * Read this equation as:
1161 *
1162 * "Packets sent once on transmission queue" MINUS
1163 * "Packets left network, but not honestly ACKed yet" PLUS
1164 * "Packets fast retransmitted"
1165 */
1166static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1167{
1168 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1169}
1170
1171#define TCP_INFINITE_SSTHRESH 0x7fffffff
1172
1173static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1174{
1175 return tp->snd_cwnd < tp->snd_ssthresh;
1176}
1177
1178static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1179{
1180 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1181}
1182
1183static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1184{
1185 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1186 (1 << inet_csk(sk)->icsk_ca_state);
1187}
1188
1189/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1190 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1191 * ssthresh.
1192 */
1193static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1194{
1195 const struct tcp_sock *tp = tcp_sk(sk);
1196
1197 if (tcp_in_cwnd_reduction(sk))
1198 return tp->snd_ssthresh;
1199 else
1200 return max(tp->snd_ssthresh,
1201 ((tp->snd_cwnd >> 1) +
1202 (tp->snd_cwnd >> 2)));
1203}
1204
1205/* Use define here intentionally to get WARN_ON location shown at the caller */
1206#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1207
1208void tcp_enter_cwr(struct sock *sk);
1209__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1210
1211/* The maximum number of MSS of available cwnd for which TSO defers
1212 * sending if not using sysctl_tcp_tso_win_divisor.
1213 */
1214static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1215{
1216 return 3;
1217}
1218
1219/* Returns end sequence number of the receiver's advertised window */
1220static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1221{
1222 return tp->snd_una + tp->snd_wnd;
1223}
1224
1225/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1226 * flexible approach. The RFC suggests cwnd should not be raised unless
1227 * it was fully used previously. And that's exactly what we do in
1228 * congestion avoidance mode. But in slow start we allow cwnd to grow
1229 * as long as the application has used half the cwnd.
1230 * Example :
1231 * cwnd is 10 (IW10), but application sends 9 frames.
1232 * We allow cwnd to reach 18 when all frames are ACKed.
1233 * This check is safe because it's as aggressive as slow start which already
1234 * risks 100% overshoot. The advantage is that we discourage application to
1235 * either send more filler packets or data to artificially blow up the cwnd
1236 * usage, and allow application-limited process to probe bw more aggressively.
1237 */
1238static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1239{
1240 const struct tcp_sock *tp = tcp_sk(sk);
1241
1242 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1243 if (tcp_in_slow_start(tp))
1244 return tp->snd_cwnd < 2 * tp->max_packets_out;
1245
1246 return tp->is_cwnd_limited;
1247}
1248
1249/* BBR congestion control needs pacing.
1250 * Same remark for SO_MAX_PACING_RATE.
1251 * sch_fq packet scheduler is efficiently handling pacing,
1252 * but is not always installed/used.
1253 * Return true if TCP stack should pace packets itself.
1254 */
1255static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1256{
1257 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1258}
1259
1260/* Return in jiffies the delay before one skb is sent.
1261 * If @skb is NULL, we look at EDT for next packet being sent on the socket.
1262 */
1263static inline unsigned long tcp_pacing_delay(const struct sock *sk,
1264 const struct sk_buff *skb)
1265{
1266 s64 pacing_delay = skb ? skb->tstamp : tcp_sk(sk)->tcp_wstamp_ns;
1267
1268 pacing_delay -= tcp_sk(sk)->tcp_clock_cache;
1269
1270 return pacing_delay > 0 ? nsecs_to_jiffies(pacing_delay) : 0;
1271}
1272
1273static inline void tcp_reset_xmit_timer(struct sock *sk,
1274 const int what,
1275 unsigned long when,
1276 const unsigned long max_when,
1277 const struct sk_buff *skb)
1278{
1279 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk, skb),
1280 max_when);
1281}
1282
1283/* Something is really bad, we could not queue an additional packet,
1284 * because qdisc is full or receiver sent a 0 window, or we are paced.
1285 * We do not want to add fuel to the fire, or abort too early,
1286 * so make sure the timer we arm now is at least 200ms in the future,
1287 * regardless of current icsk_rto value (as it could be ~2ms)
1288 */
1289static inline unsigned long tcp_probe0_base(const struct sock *sk)
1290{
1291 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1292}
1293
1294/* Variant of inet_csk_rto_backoff() used for zero window probes */
1295static inline unsigned long tcp_probe0_when(const struct sock *sk,
1296 unsigned long max_when)
1297{
1298 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1299
1300 return (unsigned long)min_t(u64, when, max_when);
1301}
1302
1303static inline void tcp_check_probe_timer(struct sock *sk)
1304{
1305 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1306 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1307 tcp_probe0_base(sk), TCP_RTO_MAX,
1308 NULL);
1309}
1310
1311static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1312{
1313 tp->snd_wl1 = seq;
1314}
1315
1316static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1317{
1318 tp->snd_wl1 = seq;
1319}
1320
1321/*
1322 * Calculate(/check) TCP checksum
1323 */
1324static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1325 __be32 daddr, __wsum base)
1326{
1327 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1328}
1329
1330static inline bool tcp_checksum_complete(struct sk_buff *skb)
1331{
1332 return !skb_csum_unnecessary(skb) &&
1333 __skb_checksum_complete(skb);
1334}
1335
1336bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1337int tcp_filter(struct sock *sk, struct sk_buff *skb);
1338void tcp_set_state(struct sock *sk, int state);
1339void tcp_done(struct sock *sk);
1340int tcp_abort(struct sock *sk, int err);
1341
1342static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1343{
1344 rx_opt->dsack = 0;
1345 rx_opt->num_sacks = 0;
1346}
1347
1348u32 tcp_default_init_rwnd(u32 mss);
1349void tcp_cwnd_restart(struct sock *sk, s32 delta);
1350
1351static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1352{
1353 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1354 struct tcp_sock *tp = tcp_sk(sk);
1355 s32 delta;
1356
1357 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1358 ca_ops->cong_control)
1359 return;
1360 delta = tcp_jiffies32 - tp->lsndtime;
1361 if (delta > inet_csk(sk)->icsk_rto)
1362 tcp_cwnd_restart(sk, delta);
1363}
1364
1365/* Determine a window scaling and initial window to offer. */
1366void tcp_select_initial_window(const struct sock *sk, int __space,
1367 __u32 mss, __u32 *rcv_wnd,
1368 __u32 *window_clamp, int wscale_ok,
1369 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1370
1371static inline int tcp_win_from_space(const struct sock *sk, int space)
1372{
1373 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1374
1375 return tcp_adv_win_scale <= 0 ?
1376 (space>>(-tcp_adv_win_scale)) :
1377 space - (space>>tcp_adv_win_scale);
1378}
1379
1380/* Note: caller must be prepared to deal with negative returns */
1381static inline int tcp_space(const struct sock *sk)
1382{
1383 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1384 READ_ONCE(sk->sk_backlog.len) -
1385 atomic_read(&sk->sk_rmem_alloc));
1386}
1387
1388static inline int tcp_full_space(const struct sock *sk)
1389{
1390 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1391}
1392
1393extern void tcp_openreq_init_rwin(struct request_sock *req,
1394 const struct sock *sk_listener,
1395 const struct dst_entry *dst);
1396
1397void tcp_enter_memory_pressure(struct sock *sk);
1398void tcp_leave_memory_pressure(struct sock *sk);
1399
1400static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1401{
1402 struct net *net = sock_net((struct sock *)tp);
1403
1404 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1405}
1406
1407static inline int keepalive_time_when(const struct tcp_sock *tp)
1408{
1409 struct net *net = sock_net((struct sock *)tp);
1410
1411 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1412}
1413
1414static inline int keepalive_probes(const struct tcp_sock *tp)
1415{
1416 struct net *net = sock_net((struct sock *)tp);
1417
1418 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1419}
1420
1421static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1422{
1423 const struct inet_connection_sock *icsk = &tp->inet_conn;
1424
1425 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1426 tcp_jiffies32 - tp->rcv_tstamp);
1427}
1428
1429static inline int tcp_fin_time(const struct sock *sk)
1430{
1431 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1432 const int rto = inet_csk(sk)->icsk_rto;
1433
1434 if (fin_timeout < (rto << 2) - (rto >> 1))
1435 fin_timeout = (rto << 2) - (rto >> 1);
1436
1437 return fin_timeout;
1438}
1439
1440static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1441 int paws_win)
1442{
1443 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1444 return true;
1445 if (unlikely(!time_before32(ktime_get_seconds(),
1446 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1447 return true;
1448 /*
1449 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1450 * then following tcp messages have valid values. Ignore 0 value,
1451 * or else 'negative' tsval might forbid us to accept their packets.
1452 */
1453 if (!rx_opt->ts_recent)
1454 return true;
1455 return false;
1456}
1457
1458static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1459 int rst)
1460{
1461 if (tcp_paws_check(rx_opt, 0))
1462 return false;
1463
1464 /* RST segments are not recommended to carry timestamp,
1465 and, if they do, it is recommended to ignore PAWS because
1466 "their cleanup function should take precedence over timestamps."
1467 Certainly, it is mistake. It is necessary to understand the reasons
1468 of this constraint to relax it: if peer reboots, clock may go
1469 out-of-sync and half-open connections will not be reset.
1470 Actually, the problem would be not existing if all
1471 the implementations followed draft about maintaining clock
1472 via reboots. Linux-2.2 DOES NOT!
1473
1474 However, we can relax time bounds for RST segments to MSL.
1475 */
1476 if (rst && !time_before32(ktime_get_seconds(),
1477 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1478 return false;
1479 return true;
1480}
1481
1482bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1483 int mib_idx, u32 *last_oow_ack_time);
1484
1485static inline void tcp_mib_init(struct net *net)
1486{
1487 /* See RFC 2012 */
1488 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1489 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1490 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1491 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1492}
1493
1494/* from STCP */
1495static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1496{
1497 tp->lost_skb_hint = NULL;
1498}
1499
1500static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1501{
1502 tcp_clear_retrans_hints_partial(tp);
1503 tp->retransmit_skb_hint = NULL;
1504}
1505
1506union tcp_md5_addr {
1507 struct in_addr a4;
1508#if IS_ENABLED(CONFIG_IPV6)
1509 struct in6_addr a6;
1510#endif
1511};
1512
1513/* - key database */
1514struct tcp_md5sig_key {
1515 struct hlist_node node;
1516 u8 keylen;
1517 u8 family; /* AF_INET or AF_INET6 */
1518 union tcp_md5_addr addr;
1519 u8 prefixlen;
1520 u8 key[TCP_MD5SIG_MAXKEYLEN];
1521 struct rcu_head rcu;
1522};
1523
1524/* - sock block */
1525struct tcp_md5sig_info {
1526 struct hlist_head head;
1527 struct rcu_head rcu;
1528};
1529
1530/* - pseudo header */
1531struct tcp4_pseudohdr {
1532 __be32 saddr;
1533 __be32 daddr;
1534 __u8 pad;
1535 __u8 protocol;
1536 __be16 len;
1537};
1538
1539struct tcp6_pseudohdr {
1540 struct in6_addr saddr;
1541 struct in6_addr daddr;
1542 __be32 len;
1543 __be32 protocol; /* including padding */
1544};
1545
1546union tcp_md5sum_block {
1547 struct tcp4_pseudohdr ip4;
1548#if IS_ENABLED(CONFIG_IPV6)
1549 struct tcp6_pseudohdr ip6;
1550#endif
1551};
1552
1553/* - pool: digest algorithm, hash description and scratch buffer */
1554struct tcp_md5sig_pool {
1555 struct ahash_request *md5_req;
1556 void *scratch;
1557};
1558
1559/* - functions */
1560int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1561 const struct sock *sk, const struct sk_buff *skb);
1562int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1563 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
1564 gfp_t gfp);
1565int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1566 int family, u8 prefixlen);
1567struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1568 const struct sock *addr_sk);
1569
1570#ifdef CONFIG_TCP_MD5SIG
1571#include <linux/jump_label.h>
1572extern struct static_key_false tcp_md5_needed;
1573struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk,
1574 const union tcp_md5_addr *addr,
1575 int family);
1576static inline struct tcp_md5sig_key *
1577tcp_md5_do_lookup(const struct sock *sk,
1578 const union tcp_md5_addr *addr,
1579 int family)
1580{
1581 if (!static_branch_unlikely(&tcp_md5_needed))
1582 return NULL;
1583 return __tcp_md5_do_lookup(sk, addr, family);
1584}
1585
1586#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1587#else
1588static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1589 const union tcp_md5_addr *addr,
1590 int family)
1591{
1592 return NULL;
1593}
1594#define tcp_twsk_md5_key(twsk) NULL
1595#endif
1596
1597bool tcp_alloc_md5sig_pool(void);
1598
1599struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1600static inline void tcp_put_md5sig_pool(void)
1601{
1602 local_bh_enable();
1603}
1604
1605int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1606 unsigned int header_len);
1607int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1608 const struct tcp_md5sig_key *key);
1609
1610/* From tcp_fastopen.c */
1611void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1612 struct tcp_fastopen_cookie *cookie);
1613void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1614 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1615 u16 try_exp);
1616struct tcp_fastopen_request {
1617 /* Fast Open cookie. Size 0 means a cookie request */
1618 struct tcp_fastopen_cookie cookie;
1619 struct msghdr *data; /* data in MSG_FASTOPEN */
1620 size_t size;
1621 int copied; /* queued in tcp_connect() */
1622 struct ubuf_info *uarg;
1623};
1624void tcp_free_fastopen_req(struct tcp_sock *tp);
1625void tcp_fastopen_destroy_cipher(struct sock *sk);
1626void tcp_fastopen_ctx_destroy(struct net *net);
1627int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1628 void *primary_key, void *backup_key);
1629void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1630struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1631 struct request_sock *req,
1632 struct tcp_fastopen_cookie *foc,
1633 const struct dst_entry *dst);
1634void tcp_fastopen_init_key_once(struct net *net);
1635bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1636 struct tcp_fastopen_cookie *cookie);
1637bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1638#define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1639#define TCP_FASTOPEN_KEY_MAX 2
1640#define TCP_FASTOPEN_KEY_BUF_LENGTH \
1641 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1642
1643/* Fastopen key context */
1644struct tcp_fastopen_context {
1645 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1646 int num;
1647 struct rcu_head rcu;
1648};
1649
1650extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1651void tcp_fastopen_active_disable(struct sock *sk);
1652bool tcp_fastopen_active_should_disable(struct sock *sk);
1653void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1654void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1655
1656/* Caller needs to wrap with rcu_read_(un)lock() */
1657static inline
1658struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1659{
1660 struct tcp_fastopen_context *ctx;
1661
1662 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1663 if (!ctx)
1664 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1665 return ctx;
1666}
1667
1668static inline
1669bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1670 const struct tcp_fastopen_cookie *orig)
1671{
1672 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1673 orig->len == foc->len &&
1674 !memcmp(orig->val, foc->val, foc->len))
1675 return true;
1676 return false;
1677}
1678
1679static inline
1680int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1681{
1682 return ctx->num;
1683}
1684
1685/* Latencies incurred by various limits for a sender. They are
1686 * chronograph-like stats that are mutually exclusive.
1687 */
1688enum tcp_chrono {
1689 TCP_CHRONO_UNSPEC,
1690 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1691 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1692 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1693 __TCP_CHRONO_MAX,
1694};
1695
1696void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1697void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1698
1699/* This helper is needed, because skb->tcp_tsorted_anchor uses
1700 * the same memory storage than skb->destructor/_skb_refdst
1701 */
1702static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1703{
1704 skb->destructor = NULL;
1705 skb->_skb_refdst = 0UL;
1706}
1707
1708#define tcp_skb_tsorted_save(skb) { \
1709 unsigned long _save = skb->_skb_refdst; \
1710 skb->_skb_refdst = 0UL;
1711
1712#define tcp_skb_tsorted_restore(skb) \
1713 skb->_skb_refdst = _save; \
1714}
1715
1716void tcp_write_queue_purge(struct sock *sk);
1717
1718static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1719{
1720 return skb_rb_first(&sk->tcp_rtx_queue);
1721}
1722
1723static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1724{
1725 return skb_rb_last(&sk->tcp_rtx_queue);
1726}
1727
1728static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1729{
1730 return skb_peek(&sk->sk_write_queue);
1731}
1732
1733static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1734{
1735 return skb_peek_tail(&sk->sk_write_queue);
1736}
1737
1738#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1739 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1740
1741static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1742{
1743 return skb_peek(&sk->sk_write_queue);
1744}
1745
1746static inline bool tcp_skb_is_last(const struct sock *sk,
1747 const struct sk_buff *skb)
1748{
1749 return skb_queue_is_last(&sk->sk_write_queue, skb);
1750}
1751
1752static inline bool tcp_write_queue_empty(const struct sock *sk)
1753{
1754 return skb_queue_empty(&sk->sk_write_queue);
1755}
1756
1757static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1758{
1759 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1760}
1761
1762static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1763{
1764 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1765}
1766
1767static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1768{
1769 __skb_queue_tail(&sk->sk_write_queue, skb);
1770
1771 /* Queue it, remembering where we must start sending. */
1772 if (sk->sk_write_queue.next == skb)
1773 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1774}
1775
1776/* Insert new before skb on the write queue of sk. */
1777static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1778 struct sk_buff *skb,
1779 struct sock *sk)
1780{
1781 __skb_queue_before(&sk->sk_write_queue, skb, new);
1782}
1783
1784static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1785{
1786 tcp_skb_tsorted_anchor_cleanup(skb);
1787 __skb_unlink(skb, &sk->sk_write_queue);
1788}
1789
1790void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1791
1792static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1793{
1794 tcp_skb_tsorted_anchor_cleanup(skb);
1795 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1796}
1797
1798static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1799{
1800 list_del(&skb->tcp_tsorted_anchor);
1801 tcp_rtx_queue_unlink(skb, sk);
1802 sk_wmem_free_skb(sk, skb);
1803}
1804
1805static inline void tcp_push_pending_frames(struct sock *sk)
1806{
1807 if (tcp_send_head(sk)) {
1808 struct tcp_sock *tp = tcp_sk(sk);
1809
1810 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1811 }
1812}
1813
1814/* Start sequence of the skb just after the highest skb with SACKed
1815 * bit, valid only if sacked_out > 0 or when the caller has ensured
1816 * validity by itself.
1817 */
1818static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1819{
1820 if (!tp->sacked_out)
1821 return tp->snd_una;
1822
1823 if (tp->highest_sack == NULL)
1824 return tp->snd_nxt;
1825
1826 return TCP_SKB_CB(tp->highest_sack)->seq;
1827}
1828
1829static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1830{
1831 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1832}
1833
1834static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1835{
1836 return tcp_sk(sk)->highest_sack;
1837}
1838
1839static inline void tcp_highest_sack_reset(struct sock *sk)
1840{
1841 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1842}
1843
1844/* Called when old skb is about to be deleted and replaced by new skb */
1845static inline void tcp_highest_sack_replace(struct sock *sk,
1846 struct sk_buff *old,
1847 struct sk_buff *new)
1848{
1849 if (old == tcp_highest_sack(sk))
1850 tcp_sk(sk)->highest_sack = new;
1851}
1852
1853/* This helper checks if socket has IP_TRANSPARENT set */
1854static inline bool inet_sk_transparent(const struct sock *sk)
1855{
1856 switch (sk->sk_state) {
1857 case TCP_TIME_WAIT:
1858 return inet_twsk(sk)->tw_transparent;
1859 case TCP_NEW_SYN_RECV:
1860 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1861 }
1862 return inet_sk(sk)->transparent;
1863}
1864
1865/* Determines whether this is a thin stream (which may suffer from
1866 * increased latency). Used to trigger latency-reducing mechanisms.
1867 */
1868static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1869{
1870 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1871}
1872
1873/* /proc */
1874enum tcp_seq_states {
1875 TCP_SEQ_STATE_LISTENING,
1876 TCP_SEQ_STATE_ESTABLISHED,
1877};
1878
1879void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
1880void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
1881void tcp_seq_stop(struct seq_file *seq, void *v);
1882
1883struct tcp_seq_afinfo {
1884 sa_family_t family;
1885};
1886
1887struct tcp_iter_state {
1888 struct seq_net_private p;
1889 enum tcp_seq_states state;
1890 struct sock *syn_wait_sk;
1891 int bucket, offset, sbucket, num;
1892 loff_t last_pos;
1893};
1894
1895extern struct request_sock_ops tcp_request_sock_ops;
1896extern struct request_sock_ops tcp6_request_sock_ops;
1897
1898void tcp_v4_destroy_sock(struct sock *sk);
1899
1900struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1901 netdev_features_t features);
1902struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
1903int tcp_gro_complete(struct sk_buff *skb);
1904
1905void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1906
1907static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1908{
1909 struct net *net = sock_net((struct sock *)tp);
1910 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1911}
1912
1913/* @wake is one when sk_stream_write_space() calls us.
1914 * This sends EPOLLOUT only if notsent_bytes is half the limit.
1915 * This mimics the strategy used in sock_def_write_space().
1916 */
1917static inline bool tcp_stream_memory_free(const struct sock *sk, int wake)
1918{
1919 const struct tcp_sock *tp = tcp_sk(sk);
1920 u32 notsent_bytes = READ_ONCE(tp->write_seq) -
1921 READ_ONCE(tp->snd_nxt);
1922
1923 return (notsent_bytes << wake) < tcp_notsent_lowat(tp);
1924}
1925
1926#ifdef CONFIG_PROC_FS
1927int tcp4_proc_init(void);
1928void tcp4_proc_exit(void);
1929#endif
1930
1931int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1932int tcp_conn_request(struct request_sock_ops *rsk_ops,
1933 const struct tcp_request_sock_ops *af_ops,
1934 struct sock *sk, struct sk_buff *skb);
1935
1936/* TCP af-specific functions */
1937struct tcp_sock_af_ops {
1938#ifdef CONFIG_TCP_MD5SIG
1939 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1940 const struct sock *addr_sk);
1941 int (*calc_md5_hash)(char *location,
1942 const struct tcp_md5sig_key *md5,
1943 const struct sock *sk,
1944 const struct sk_buff *skb);
1945 int (*md5_parse)(struct sock *sk,
1946 int optname,
1947 char __user *optval,
1948 int optlen);
1949#endif
1950};
1951
1952struct tcp_request_sock_ops {
1953 u16 mss_clamp;
1954#ifdef CONFIG_TCP_MD5SIG
1955 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1956 const struct sock *addr_sk);
1957 int (*calc_md5_hash) (char *location,
1958 const struct tcp_md5sig_key *md5,
1959 const struct sock *sk,
1960 const struct sk_buff *skb);
1961#endif
1962 void (*init_req)(struct request_sock *req,
1963 const struct sock *sk_listener,
1964 struct sk_buff *skb);
1965#ifdef CONFIG_SYN_COOKIES
1966 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1967 __u16 *mss);
1968#endif
1969 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1970 const struct request_sock *req);
1971 u32 (*init_seq)(const struct sk_buff *skb);
1972 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1973 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1974 struct flowi *fl, struct request_sock *req,
1975 struct tcp_fastopen_cookie *foc,
1976 enum tcp_synack_type synack_type);
1977};
1978
1979#ifdef CONFIG_SYN_COOKIES
1980static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1981 const struct sock *sk, struct sk_buff *skb,
1982 __u16 *mss)
1983{
1984 tcp_synq_overflow(sk);
1985 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1986 return ops->cookie_init_seq(skb, mss);
1987}
1988#else
1989static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1990 const struct sock *sk, struct sk_buff *skb,
1991 __u16 *mss)
1992{
1993 return 0;
1994}
1995#endif
1996
1997int tcpv4_offload_init(void);
1998
1999void tcp_v4_init(void);
2000void tcp_init(void);
2001
2002/* tcp_recovery.c */
2003void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2004void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2005extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2006 u32 reo_wnd);
2007extern void tcp_rack_mark_lost(struct sock *sk);
2008extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2009 u64 xmit_time);
2010extern void tcp_rack_reo_timeout(struct sock *sk);
2011extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2012
2013/* At how many usecs into the future should the RTO fire? */
2014static inline s64 tcp_rto_delta_us(const struct sock *sk)
2015{
2016 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2017 u32 rto = inet_csk(sk)->icsk_rto;
2018 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2019
2020 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2021}
2022
2023/*
2024 * Save and compile IPv4 options, return a pointer to it
2025 */
2026static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2027 struct sk_buff *skb)
2028{
2029 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2030 struct ip_options_rcu *dopt = NULL;
2031
2032 if (opt->optlen) {
2033 int opt_size = sizeof(*dopt) + opt->optlen;
2034
2035 dopt = kmalloc(opt_size, GFP_ATOMIC);
2036 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2037 kfree(dopt);
2038 dopt = NULL;
2039 }
2040 }
2041 return dopt;
2042}
2043
2044/* locally generated TCP pure ACKs have skb->truesize == 2
2045 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2046 * This is much faster than dissecting the packet to find out.
2047 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2048 */
2049static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2050{
2051 return skb->truesize == 2;
2052}
2053
2054static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2055{
2056 skb->truesize = 2;
2057}
2058
2059static inline int tcp_inq(struct sock *sk)
2060{
2061 struct tcp_sock *tp = tcp_sk(sk);
2062 int answ;
2063
2064 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2065 answ = 0;
2066 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2067 !tp->urg_data ||
2068 before(tp->urg_seq, tp->copied_seq) ||
2069 !before(tp->urg_seq, tp->rcv_nxt)) {
2070
2071 answ = tp->rcv_nxt - tp->copied_seq;
2072
2073 /* Subtract 1, if FIN was received */
2074 if (answ && sock_flag(sk, SOCK_DONE))
2075 answ--;
2076 } else {
2077 answ = tp->urg_seq - tp->copied_seq;
2078 }
2079
2080 return answ;
2081}
2082
2083int tcp_peek_len(struct socket *sock);
2084
2085static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2086{
2087 u16 segs_in;
2088
2089 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2090 tp->segs_in += segs_in;
2091 if (skb->len > tcp_hdrlen(skb))
2092 tp->data_segs_in += segs_in;
2093}
2094
2095/*
2096 * TCP listen path runs lockless.
2097 * We forced "struct sock" to be const qualified to make sure
2098 * we don't modify one of its field by mistake.
2099 * Here, we increment sk_drops which is an atomic_t, so we can safely
2100 * make sock writable again.
2101 */
2102static inline void tcp_listendrop(const struct sock *sk)
2103{
2104 atomic_inc(&((struct sock *)sk)->sk_drops);
2105 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2106}
2107
2108enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2109
2110/*
2111 * Interface for adding Upper Level Protocols over TCP
2112 */
2113
2114#define TCP_ULP_NAME_MAX 16
2115#define TCP_ULP_MAX 128
2116#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2117
2118struct tcp_ulp_ops {
2119 struct list_head list;
2120
2121 /* initialize ulp */
2122 int (*init)(struct sock *sk);
2123 /* update ulp */
2124 void (*update)(struct sock *sk, struct proto *p);
2125 /* cleanup ulp */
2126 void (*release)(struct sock *sk);
2127 /* diagnostic */
2128 int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2129 size_t (*get_info_size)(const struct sock *sk);
2130
2131 char name[TCP_ULP_NAME_MAX];
2132 struct module *owner;
2133};
2134int tcp_register_ulp(struct tcp_ulp_ops *type);
2135void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2136int tcp_set_ulp(struct sock *sk, const char *name);
2137void tcp_get_available_ulp(char *buf, size_t len);
2138void tcp_cleanup_ulp(struct sock *sk);
2139void tcp_update_ulp(struct sock *sk, struct proto *p);
2140
2141#define MODULE_ALIAS_TCP_ULP(name) \
2142 __MODULE_INFO(alias, alias_userspace, name); \
2143 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2144
2145struct sk_msg;
2146struct sk_psock;
2147
2148int tcp_bpf_init(struct sock *sk);
2149void tcp_bpf_reinit(struct sock *sk);
2150int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
2151 int flags);
2152int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
2153 int nonblock, int flags, int *addr_len);
2154int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
2155 struct msghdr *msg, int len, int flags);
2156
2157/* Call BPF_SOCK_OPS program that returns an int. If the return value
2158 * is < 0, then the BPF op failed (for example if the loaded BPF
2159 * program does not support the chosen operation or there is no BPF
2160 * program loaded).
2161 */
2162#ifdef CONFIG_BPF
2163static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2164{
2165 struct bpf_sock_ops_kern sock_ops;
2166 int ret;
2167
2168 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2169 if (sk_fullsock(sk)) {
2170 sock_ops.is_fullsock = 1;
2171 sock_owned_by_me(sk);
2172 }
2173
2174 sock_ops.sk = sk;
2175 sock_ops.op = op;
2176 if (nargs > 0)
2177 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2178
2179 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2180 if (ret == 0)
2181 ret = sock_ops.reply;
2182 else
2183 ret = -1;
2184 return ret;
2185}
2186
2187static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2188{
2189 u32 args[2] = {arg1, arg2};
2190
2191 return tcp_call_bpf(sk, op, 2, args);
2192}
2193
2194static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2195 u32 arg3)
2196{
2197 u32 args[3] = {arg1, arg2, arg3};
2198
2199 return tcp_call_bpf(sk, op, 3, args);
2200}
2201
2202#else
2203static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2204{
2205 return -EPERM;
2206}
2207
2208static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2209{
2210 return -EPERM;
2211}
2212
2213static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2214 u32 arg3)
2215{
2216 return -EPERM;
2217}
2218
2219#endif
2220
2221static inline u32 tcp_timeout_init(struct sock *sk)
2222{
2223 int timeout;
2224
2225 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2226
2227 if (timeout <= 0)
2228 timeout = TCP_TIMEOUT_INIT;
2229 return timeout;
2230}
2231
2232static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2233{
2234 int rwnd;
2235
2236 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2237
2238 if (rwnd < 0)
2239 rwnd = 0;
2240 return rwnd;
2241}
2242
2243static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2244{
2245 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2246}
2247
2248static inline void tcp_bpf_rtt(struct sock *sk)
2249{
2250 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2251 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2252}
2253
2254#if IS_ENABLED(CONFIG_SMC)
2255extern struct static_key_false tcp_have_smc;
2256#endif
2257
2258#if IS_ENABLED(CONFIG_TLS_DEVICE)
2259void clean_acked_data_enable(struct inet_connection_sock *icsk,
2260 void (*cad)(struct sock *sk, u32 ack_seq));
2261void clean_acked_data_disable(struct inet_connection_sock *icsk);
2262void clean_acked_data_flush(void);
2263#endif
2264
2265DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2266static inline void tcp_add_tx_delay(struct sk_buff *skb,
2267 const struct tcp_sock *tp)
2268{
2269 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2270 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2271}
2272
2273/* Compute Earliest Departure Time for some control packets
2274 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2275 */
2276static inline u64 tcp_transmit_time(const struct sock *sk)
2277{
2278 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2279 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2280 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2281
2282 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;
2283 }
2284 return 0;
2285}
2286
2287#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/dmaengine.h>
31#include <linux/crypto.h>
32#include <linux/cryptohash.h>
33#include <linux/kref.h>
34
35#include <net/inet_connection_sock.h>
36#include <net/inet_timewait_sock.h>
37#include <net/inet_hashtables.h>
38#include <net/checksum.h>
39#include <net/request_sock.h>
40#include <net/sock.h>
41#include <net/snmp.h>
42#include <net/ip.h>
43#include <net/tcp_states.h>
44#include <net/inet_ecn.h>
45#include <net/dst.h>
46
47#include <linux/seq_file.h>
48#include <linux/memcontrol.h>
49
50extern struct inet_hashinfo tcp_hashinfo;
51
52extern struct percpu_counter tcp_orphan_count;
53extern void tcp_time_wait(struct sock *sk, int state, int timeo);
54
55#define MAX_TCP_HEADER (128 + MAX_HEADER)
56#define MAX_TCP_OPTION_SPACE 40
57
58/*
59 * Never offer a window over 32767 without using window scaling. Some
60 * poor stacks do signed 16bit maths!
61 */
62#define MAX_TCP_WINDOW 32767U
63
64/* Offer an initial receive window of 10 mss. */
65#define TCP_DEFAULT_INIT_RCVWND 10
66
67/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68#define TCP_MIN_MSS 88U
69
70/* The least MTU to use for probing */
71#define TCP_BASE_MSS 512
72
73/* After receiving this amount of duplicate ACKs fast retransmit starts. */
74#define TCP_FASTRETRANS_THRESH 3
75
76/* Maximal reordering. */
77#define TCP_MAX_REORDERING 127
78
79/* Maximal number of ACKs sent quickly to accelerate slow-start. */
80#define TCP_MAX_QUICKACKS 16U
81
82/* urg_data states */
83#define TCP_URG_VALID 0x0100
84#define TCP_URG_NOTYET 0x0200
85#define TCP_URG_READ 0x0400
86
87#define TCP_RETR1 3 /*
88 * This is how many retries it does before it
89 * tries to figure out if the gateway is
90 * down. Minimal RFC value is 3; it corresponds
91 * to ~3sec-8min depending on RTO.
92 */
93
94#define TCP_RETR2 15 /*
95 * This should take at least
96 * 90 minutes to time out.
97 * RFC1122 says that the limit is 100 sec.
98 * 15 is ~13-30min depending on RTO.
99 */
100
101#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
102 * connection: ~180sec is RFC minimum */
103
104#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
105 * connection: ~180sec is RFC minimum */
106
107#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
108 * state, about 60 seconds */
109#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
110 /* BSD style FIN_WAIT2 deadlock breaker.
111 * It used to be 3min, new value is 60sec,
112 * to combine FIN-WAIT-2 timeout with
113 * TIME-WAIT timer.
114 */
115
116#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
117#if HZ >= 100
118#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
119#define TCP_ATO_MIN ((unsigned)(HZ/25))
120#else
121#define TCP_DELACK_MIN 4U
122#define TCP_ATO_MIN 4U
123#endif
124#define TCP_RTO_MAX ((unsigned)(120*HZ))
125#define TCP_RTO_MIN ((unsigned)(HZ/5))
126#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
127#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
128 * used as a fallback RTO for the
129 * initial data transmission if no
130 * valid RTT sample has been acquired,
131 * most likely due to retrans in 3WHS.
132 */
133
134#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
135 * for local resources.
136 */
137
138#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
139#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
140#define TCP_KEEPALIVE_INTVL (75*HZ)
141
142#define MAX_TCP_KEEPIDLE 32767
143#define MAX_TCP_KEEPINTVL 32767
144#define MAX_TCP_KEEPCNT 127
145#define MAX_TCP_SYNCNT 127
146
147#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
148
149#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
150#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
151 * after this time. It should be equal
152 * (or greater than) TCP_TIMEWAIT_LEN
153 * to provide reliability equal to one
154 * provided by timewait state.
155 */
156#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
157 * timestamps. It must be less than
158 * minimal timewait lifetime.
159 */
160/*
161 * TCP option
162 */
163
164#define TCPOPT_NOP 1 /* Padding */
165#define TCPOPT_EOL 0 /* End of options */
166#define TCPOPT_MSS 2 /* Segment size negotiating */
167#define TCPOPT_WINDOW 3 /* Window scaling */
168#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
169#define TCPOPT_SACK 5 /* SACK Block */
170#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
171#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
172#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
173
174/*
175 * TCP option lengths
176 */
177
178#define TCPOLEN_MSS 4
179#define TCPOLEN_WINDOW 3
180#define TCPOLEN_SACK_PERM 2
181#define TCPOLEN_TIMESTAMP 10
182#define TCPOLEN_MD5SIG 18
183#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
184#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
185#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
186#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
187
188/* But this is what stacks really send out. */
189#define TCPOLEN_TSTAMP_ALIGNED 12
190#define TCPOLEN_WSCALE_ALIGNED 4
191#define TCPOLEN_SACKPERM_ALIGNED 4
192#define TCPOLEN_SACK_BASE 2
193#define TCPOLEN_SACK_BASE_ALIGNED 4
194#define TCPOLEN_SACK_PERBLOCK 8
195#define TCPOLEN_MD5SIG_ALIGNED 20
196#define TCPOLEN_MSS_ALIGNED 4
197
198/* Flags in tp->nonagle */
199#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
200#define TCP_NAGLE_CORK 2 /* Socket is corked */
201#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
202
203/* TCP thin-stream limits */
204#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
205
206/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
207#define TCP_INIT_CWND 10
208
209extern struct inet_timewait_death_row tcp_death_row;
210
211/* sysctl variables for tcp */
212extern int sysctl_tcp_timestamps;
213extern int sysctl_tcp_window_scaling;
214extern int sysctl_tcp_sack;
215extern int sysctl_tcp_fin_timeout;
216extern int sysctl_tcp_keepalive_time;
217extern int sysctl_tcp_keepalive_probes;
218extern int sysctl_tcp_keepalive_intvl;
219extern int sysctl_tcp_syn_retries;
220extern int sysctl_tcp_synack_retries;
221extern int sysctl_tcp_retries1;
222extern int sysctl_tcp_retries2;
223extern int sysctl_tcp_orphan_retries;
224extern int sysctl_tcp_syncookies;
225extern int sysctl_tcp_retrans_collapse;
226extern int sysctl_tcp_stdurg;
227extern int sysctl_tcp_rfc1337;
228extern int sysctl_tcp_abort_on_overflow;
229extern int sysctl_tcp_max_orphans;
230extern int sysctl_tcp_fack;
231extern int sysctl_tcp_reordering;
232extern int sysctl_tcp_ecn;
233extern int sysctl_tcp_dsack;
234extern int sysctl_tcp_wmem[3];
235extern int sysctl_tcp_rmem[3];
236extern int sysctl_tcp_app_win;
237extern int sysctl_tcp_adv_win_scale;
238extern int sysctl_tcp_tw_reuse;
239extern int sysctl_tcp_frto;
240extern int sysctl_tcp_frto_response;
241extern int sysctl_tcp_low_latency;
242extern int sysctl_tcp_dma_copybreak;
243extern int sysctl_tcp_nometrics_save;
244extern int sysctl_tcp_moderate_rcvbuf;
245extern int sysctl_tcp_tso_win_divisor;
246extern int sysctl_tcp_abc;
247extern int sysctl_tcp_mtu_probing;
248extern int sysctl_tcp_base_mss;
249extern int sysctl_tcp_workaround_signed_windows;
250extern int sysctl_tcp_slow_start_after_idle;
251extern int sysctl_tcp_max_ssthresh;
252extern int sysctl_tcp_cookie_size;
253extern int sysctl_tcp_thin_linear_timeouts;
254extern int sysctl_tcp_thin_dupack;
255extern int sysctl_tcp_early_retrans;
256
257extern atomic_long_t tcp_memory_allocated;
258extern struct percpu_counter tcp_sockets_allocated;
259extern int tcp_memory_pressure;
260
261/*
262 * The next routines deal with comparing 32 bit unsigned ints
263 * and worry about wraparound (automatic with unsigned arithmetic).
264 */
265
266static inline bool before(__u32 seq1, __u32 seq2)
267{
268 return (__s32)(seq1-seq2) < 0;
269}
270#define after(seq2, seq1) before(seq1, seq2)
271
272/* is s2<=s1<=s3 ? */
273static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
274{
275 return seq3 - seq2 >= seq1 - seq2;
276}
277
278static inline bool tcp_out_of_memory(struct sock *sk)
279{
280 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
281 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
282 return true;
283 return false;
284}
285
286static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
287{
288 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
289 int orphans = percpu_counter_read_positive(ocp);
290
291 if (orphans << shift > sysctl_tcp_max_orphans) {
292 orphans = percpu_counter_sum_positive(ocp);
293 if (orphans << shift > sysctl_tcp_max_orphans)
294 return true;
295 }
296 return false;
297}
298
299extern bool tcp_check_oom(struct sock *sk, int shift);
300
301/* syncookies: remember time of last synqueue overflow */
302static inline void tcp_synq_overflow(struct sock *sk)
303{
304 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
305}
306
307/* syncookies: no recent synqueue overflow on this listening socket? */
308static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
309{
310 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
311 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
312}
313
314extern struct proto tcp_prot;
315
316#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
317#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
318#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
319#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
320#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
321
322extern void tcp_init_mem(struct net *net);
323
324extern void tcp_v4_err(struct sk_buff *skb, u32);
325
326extern void tcp_shutdown (struct sock *sk, int how);
327
328extern int tcp_v4_rcv(struct sk_buff *skb);
329
330extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
331extern void *tcp_v4_tw_get_peer(struct sock *sk);
332extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
333extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
334 size_t size);
335extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
336 size_t size, int flags);
337extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
338extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
339 const struct tcphdr *th, unsigned int len);
340extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
341 const struct tcphdr *th, unsigned int len);
342extern void tcp_rcv_space_adjust(struct sock *sk);
343extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
344extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
345extern void tcp_twsk_destructor(struct sock *sk);
346extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
347 struct pipe_inode_info *pipe, size_t len,
348 unsigned int flags);
349
350static inline void tcp_dec_quickack_mode(struct sock *sk,
351 const unsigned int pkts)
352{
353 struct inet_connection_sock *icsk = inet_csk(sk);
354
355 if (icsk->icsk_ack.quick) {
356 if (pkts >= icsk->icsk_ack.quick) {
357 icsk->icsk_ack.quick = 0;
358 /* Leaving quickack mode we deflate ATO. */
359 icsk->icsk_ack.ato = TCP_ATO_MIN;
360 } else
361 icsk->icsk_ack.quick -= pkts;
362 }
363}
364
365#define TCP_ECN_OK 1
366#define TCP_ECN_QUEUE_CWR 2
367#define TCP_ECN_DEMAND_CWR 4
368#define TCP_ECN_SEEN 8
369
370enum tcp_tw_status {
371 TCP_TW_SUCCESS = 0,
372 TCP_TW_RST = 1,
373 TCP_TW_ACK = 2,
374 TCP_TW_SYN = 3
375};
376
377
378extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
379 struct sk_buff *skb,
380 const struct tcphdr *th);
381extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
382 struct request_sock *req,
383 struct request_sock **prev);
384extern int tcp_child_process(struct sock *parent, struct sock *child,
385 struct sk_buff *skb);
386extern bool tcp_use_frto(struct sock *sk);
387extern void tcp_enter_frto(struct sock *sk);
388extern void tcp_enter_loss(struct sock *sk, int how);
389extern void tcp_clear_retrans(struct tcp_sock *tp);
390extern void tcp_update_metrics(struct sock *sk);
391extern void tcp_close(struct sock *sk, long timeout);
392extern void tcp_init_sock(struct sock *sk);
393extern unsigned int tcp_poll(struct file * file, struct socket *sock,
394 struct poll_table_struct *wait);
395extern int tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397extern int tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
400 char __user *optval, int __user *optlen);
401extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
402 char __user *optval, unsigned int optlen);
403extern void tcp_set_keepalive(struct sock *sk, int val);
404extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
405extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
406 size_t len, int nonblock, int flags, int *addr_len);
407extern void tcp_parse_options(const struct sk_buff *skb,
408 struct tcp_options_received *opt_rx, const u8 **hvpp,
409 int estab);
410extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
411
412/*
413 * TCP v4 functions exported for the inet6 API
414 */
415
416extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
417extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
418extern struct sock * tcp_create_openreq_child(struct sock *sk,
419 struct request_sock *req,
420 struct sk_buff *skb);
421extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
422 struct request_sock *req,
423 struct dst_entry *dst);
424extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
425extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
426 int addr_len);
427extern int tcp_connect(struct sock *sk);
428extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
429 struct request_sock *req,
430 struct request_values *rvp);
431extern int tcp_disconnect(struct sock *sk, int flags);
432
433void tcp_connect_init(struct sock *sk);
434void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
435int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
436
437/* From syncookies.c */
438extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
439extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
440 struct ip_options *opt);
441#ifdef CONFIG_SYN_COOKIES
442extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
443 __u16 *mss);
444#else
445static inline __u32 cookie_v4_init_sequence(struct sock *sk,
446 struct sk_buff *skb,
447 __u16 *mss)
448{
449 return 0;
450}
451#endif
452
453extern __u32 cookie_init_timestamp(struct request_sock *req);
454extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
455
456/* From net/ipv6/syncookies.c */
457extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
458#ifdef CONFIG_SYN_COOKIES
459extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
460 __u16 *mss);
461#else
462static inline __u32 cookie_v6_init_sequence(struct sock *sk,
463 struct sk_buff *skb,
464 __u16 *mss)
465{
466 return 0;
467}
468#endif
469/* tcp_output.c */
470
471extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
472 int nonagle);
473extern bool tcp_may_send_now(struct sock *sk);
474extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
475extern void tcp_retransmit_timer(struct sock *sk);
476extern void tcp_xmit_retransmit_queue(struct sock *);
477extern void tcp_simple_retransmit(struct sock *);
478extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
479extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
480
481extern void tcp_send_probe0(struct sock *);
482extern void tcp_send_partial(struct sock *);
483extern int tcp_write_wakeup(struct sock *);
484extern void tcp_send_fin(struct sock *sk);
485extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
486extern int tcp_send_synack(struct sock *);
487extern bool tcp_syn_flood_action(struct sock *sk,
488 const struct sk_buff *skb,
489 const char *proto);
490extern void tcp_push_one(struct sock *, unsigned int mss_now);
491extern void tcp_send_ack(struct sock *sk);
492extern void tcp_send_delayed_ack(struct sock *sk);
493
494/* tcp_input.c */
495extern void tcp_cwnd_application_limited(struct sock *sk);
496extern void tcp_resume_early_retransmit(struct sock *sk);
497extern void tcp_rearm_rto(struct sock *sk);
498
499/* tcp_timer.c */
500extern void tcp_init_xmit_timers(struct sock *);
501static inline void tcp_clear_xmit_timers(struct sock *sk)
502{
503 inet_csk_clear_xmit_timers(sk);
504}
505
506extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
507extern unsigned int tcp_current_mss(struct sock *sk);
508
509/* Bound MSS / TSO packet size with the half of the window */
510static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
511{
512 int cutoff;
513
514 /* When peer uses tiny windows, there is no use in packetizing
515 * to sub-MSS pieces for the sake of SWS or making sure there
516 * are enough packets in the pipe for fast recovery.
517 *
518 * On the other hand, for extremely large MSS devices, handling
519 * smaller than MSS windows in this way does make sense.
520 */
521 if (tp->max_window >= 512)
522 cutoff = (tp->max_window >> 1);
523 else
524 cutoff = tp->max_window;
525
526 if (cutoff && pktsize > cutoff)
527 return max_t(int, cutoff, 68U - tp->tcp_header_len);
528 else
529 return pktsize;
530}
531
532/* tcp.c */
533extern void tcp_get_info(const struct sock *, struct tcp_info *);
534
535/* Read 'sendfile()'-style from a TCP socket */
536typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
537 unsigned int, size_t);
538extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
539 sk_read_actor_t recv_actor);
540
541extern void tcp_initialize_rcv_mss(struct sock *sk);
542
543extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
544extern int tcp_mss_to_mtu(struct sock *sk, int mss);
545extern void tcp_mtup_init(struct sock *sk);
546extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
547
548static inline void tcp_bound_rto(const struct sock *sk)
549{
550 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
551 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
552}
553
554static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
555{
556 return (tp->srtt >> 3) + tp->rttvar;
557}
558
559static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
560{
561 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
562 ntohl(TCP_FLAG_ACK) |
563 snd_wnd);
564}
565
566static inline void tcp_fast_path_on(struct tcp_sock *tp)
567{
568 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
569}
570
571static inline void tcp_fast_path_check(struct sock *sk)
572{
573 struct tcp_sock *tp = tcp_sk(sk);
574
575 if (skb_queue_empty(&tp->out_of_order_queue) &&
576 tp->rcv_wnd &&
577 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
578 !tp->urg_data)
579 tcp_fast_path_on(tp);
580}
581
582/* Compute the actual rto_min value */
583static inline u32 tcp_rto_min(struct sock *sk)
584{
585 const struct dst_entry *dst = __sk_dst_get(sk);
586 u32 rto_min = TCP_RTO_MIN;
587
588 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
589 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
590 return rto_min;
591}
592
593/* Compute the actual receive window we are currently advertising.
594 * Rcv_nxt can be after the window if our peer push more data
595 * than the offered window.
596 */
597static inline u32 tcp_receive_window(const struct tcp_sock *tp)
598{
599 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
600
601 if (win < 0)
602 win = 0;
603 return (u32) win;
604}
605
606/* Choose a new window, without checks for shrinking, and without
607 * scaling applied to the result. The caller does these things
608 * if necessary. This is a "raw" window selection.
609 */
610extern u32 __tcp_select_window(struct sock *sk);
611
612void tcp_send_window_probe(struct sock *sk);
613
614/* TCP timestamps are only 32-bits, this causes a slight
615 * complication on 64-bit systems since we store a snapshot
616 * of jiffies in the buffer control blocks below. We decided
617 * to use only the low 32-bits of jiffies and hide the ugly
618 * casts with the following macro.
619 */
620#define tcp_time_stamp ((__u32)(jiffies))
621
622#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
623
624#define TCPHDR_FIN 0x01
625#define TCPHDR_SYN 0x02
626#define TCPHDR_RST 0x04
627#define TCPHDR_PSH 0x08
628#define TCPHDR_ACK 0x10
629#define TCPHDR_URG 0x20
630#define TCPHDR_ECE 0x40
631#define TCPHDR_CWR 0x80
632
633/* This is what the send packet queuing engine uses to pass
634 * TCP per-packet control information to the transmission code.
635 * We also store the host-order sequence numbers in here too.
636 * This is 44 bytes if IPV6 is enabled.
637 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
638 */
639struct tcp_skb_cb {
640 union {
641 struct inet_skb_parm h4;
642#if IS_ENABLED(CONFIG_IPV6)
643 struct inet6_skb_parm h6;
644#endif
645 } header; /* For incoming frames */
646 __u32 seq; /* Starting sequence number */
647 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
648 __u32 when; /* used to compute rtt's */
649 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
650
651 __u8 sacked; /* State flags for SACK/FACK. */
652#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
653#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
654#define TCPCB_LOST 0x04 /* SKB is lost */
655#define TCPCB_TAGBITS 0x07 /* All tag bits */
656#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
657#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
658
659 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
660 /* 1 byte hole */
661 __u32 ack_seq; /* Sequence number ACK'd */
662};
663
664#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
665
666/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
667 *
668 * If we receive a SYN packet with these bits set, it means a network is
669 * playing bad games with TOS bits. In order to avoid possible false congestion
670 * notifications, we disable TCP ECN negociation.
671 */
672static inline void
673TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb)
674{
675 const struct tcphdr *th = tcp_hdr(skb);
676
677 if (sysctl_tcp_ecn && th->ece && th->cwr &&
678 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
679 inet_rsk(req)->ecn_ok = 1;
680}
681
682/* Due to TSO, an SKB can be composed of multiple actual
683 * packets. To keep these tracked properly, we use this.
684 */
685static inline int tcp_skb_pcount(const struct sk_buff *skb)
686{
687 return skb_shinfo(skb)->gso_segs;
688}
689
690/* This is valid iff tcp_skb_pcount() > 1. */
691static inline int tcp_skb_mss(const struct sk_buff *skb)
692{
693 return skb_shinfo(skb)->gso_size;
694}
695
696/* Events passed to congestion control interface */
697enum tcp_ca_event {
698 CA_EVENT_TX_START, /* first transmit when no packets in flight */
699 CA_EVENT_CWND_RESTART, /* congestion window restart */
700 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
701 CA_EVENT_FRTO, /* fast recovery timeout */
702 CA_EVENT_LOSS, /* loss timeout */
703 CA_EVENT_FAST_ACK, /* in sequence ack */
704 CA_EVENT_SLOW_ACK, /* other ack */
705};
706
707/*
708 * Interface for adding new TCP congestion control handlers
709 */
710#define TCP_CA_NAME_MAX 16
711#define TCP_CA_MAX 128
712#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
713
714#define TCP_CONG_NON_RESTRICTED 0x1
715#define TCP_CONG_RTT_STAMP 0x2
716
717struct tcp_congestion_ops {
718 struct list_head list;
719 unsigned long flags;
720
721 /* initialize private data (optional) */
722 void (*init)(struct sock *sk);
723 /* cleanup private data (optional) */
724 void (*release)(struct sock *sk);
725
726 /* return slow start threshold (required) */
727 u32 (*ssthresh)(struct sock *sk);
728 /* lower bound for congestion window (optional) */
729 u32 (*min_cwnd)(const struct sock *sk);
730 /* do new cwnd calculation (required) */
731 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
732 /* call before changing ca_state (optional) */
733 void (*set_state)(struct sock *sk, u8 new_state);
734 /* call when cwnd event occurs (optional) */
735 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
736 /* new value of cwnd after loss (optional) */
737 u32 (*undo_cwnd)(struct sock *sk);
738 /* hook for packet ack accounting (optional) */
739 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
740 /* get info for inet_diag (optional) */
741 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
742
743 char name[TCP_CA_NAME_MAX];
744 struct module *owner;
745};
746
747extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
748extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
749
750extern void tcp_init_congestion_control(struct sock *sk);
751extern void tcp_cleanup_congestion_control(struct sock *sk);
752extern int tcp_set_default_congestion_control(const char *name);
753extern void tcp_get_default_congestion_control(char *name);
754extern void tcp_get_available_congestion_control(char *buf, size_t len);
755extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
756extern int tcp_set_allowed_congestion_control(char *allowed);
757extern int tcp_set_congestion_control(struct sock *sk, const char *name);
758extern void tcp_slow_start(struct tcp_sock *tp);
759extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
760
761extern struct tcp_congestion_ops tcp_init_congestion_ops;
762extern u32 tcp_reno_ssthresh(struct sock *sk);
763extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
764extern u32 tcp_reno_min_cwnd(const struct sock *sk);
765extern struct tcp_congestion_ops tcp_reno;
766
767static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
768{
769 struct inet_connection_sock *icsk = inet_csk(sk);
770
771 if (icsk->icsk_ca_ops->set_state)
772 icsk->icsk_ca_ops->set_state(sk, ca_state);
773 icsk->icsk_ca_state = ca_state;
774}
775
776static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
777{
778 const struct inet_connection_sock *icsk = inet_csk(sk);
779
780 if (icsk->icsk_ca_ops->cwnd_event)
781 icsk->icsk_ca_ops->cwnd_event(sk, event);
782}
783
784/* These functions determine how the current flow behaves in respect of SACK
785 * handling. SACK is negotiated with the peer, and therefore it can vary
786 * between different flows.
787 *
788 * tcp_is_sack - SACK enabled
789 * tcp_is_reno - No SACK
790 * tcp_is_fack - FACK enabled, implies SACK enabled
791 */
792static inline int tcp_is_sack(const struct tcp_sock *tp)
793{
794 return tp->rx_opt.sack_ok;
795}
796
797static inline bool tcp_is_reno(const struct tcp_sock *tp)
798{
799 return !tcp_is_sack(tp);
800}
801
802static inline bool tcp_is_fack(const struct tcp_sock *tp)
803{
804 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
805}
806
807static inline void tcp_enable_fack(struct tcp_sock *tp)
808{
809 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
810}
811
812/* TCP early-retransmit (ER) is similar to but more conservative than
813 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
814 */
815static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
816{
817 tp->do_early_retrans = sysctl_tcp_early_retrans &&
818 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3;
819 tp->early_retrans_delayed = 0;
820}
821
822static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
823{
824 tp->do_early_retrans = 0;
825}
826
827static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
828{
829 return tp->sacked_out + tp->lost_out;
830}
831
832/* This determines how many packets are "in the network" to the best
833 * of our knowledge. In many cases it is conservative, but where
834 * detailed information is available from the receiver (via SACK
835 * blocks etc.) we can make more aggressive calculations.
836 *
837 * Use this for decisions involving congestion control, use just
838 * tp->packets_out to determine if the send queue is empty or not.
839 *
840 * Read this equation as:
841 *
842 * "Packets sent once on transmission queue" MINUS
843 * "Packets left network, but not honestly ACKed yet" PLUS
844 * "Packets fast retransmitted"
845 */
846static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
847{
848 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
849}
850
851#define TCP_INFINITE_SSTHRESH 0x7fffffff
852
853static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
854{
855 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
856}
857
858/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
859 * The exception is rate halving phase, when cwnd is decreasing towards
860 * ssthresh.
861 */
862static inline __u32 tcp_current_ssthresh(const struct sock *sk)
863{
864 const struct tcp_sock *tp = tcp_sk(sk);
865
866 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
867 return tp->snd_ssthresh;
868 else
869 return max(tp->snd_ssthresh,
870 ((tp->snd_cwnd >> 1) +
871 (tp->snd_cwnd >> 2)));
872}
873
874/* Use define here intentionally to get WARN_ON location shown at the caller */
875#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
876
877extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
878extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
879
880/* The maximum number of MSS of available cwnd for which TSO defers
881 * sending if not using sysctl_tcp_tso_win_divisor.
882 */
883static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
884{
885 return 3;
886}
887
888/* Slow start with delack produces 3 packets of burst, so that
889 * it is safe "de facto". This will be the default - same as
890 * the default reordering threshold - but if reordering increases,
891 * we must be able to allow cwnd to burst at least this much in order
892 * to not pull it back when holes are filled.
893 */
894static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
895{
896 return tp->reordering;
897}
898
899/* Returns end sequence number of the receiver's advertised window */
900static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
901{
902 return tp->snd_una + tp->snd_wnd;
903}
904extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
905
906static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
907 const struct sk_buff *skb)
908{
909 if (skb->len < mss)
910 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
911}
912
913static inline void tcp_check_probe_timer(struct sock *sk)
914{
915 const struct tcp_sock *tp = tcp_sk(sk);
916 const struct inet_connection_sock *icsk = inet_csk(sk);
917
918 if (!tp->packets_out && !icsk->icsk_pending)
919 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
920 icsk->icsk_rto, TCP_RTO_MAX);
921}
922
923static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
924{
925 tp->snd_wl1 = seq;
926}
927
928static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
929{
930 tp->snd_wl1 = seq;
931}
932
933/*
934 * Calculate(/check) TCP checksum
935 */
936static inline __sum16 tcp_v4_check(int len, __be32 saddr,
937 __be32 daddr, __wsum base)
938{
939 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
940}
941
942static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
943{
944 return __skb_checksum_complete(skb);
945}
946
947static inline bool tcp_checksum_complete(struct sk_buff *skb)
948{
949 return !skb_csum_unnecessary(skb) &&
950 __tcp_checksum_complete(skb);
951}
952
953/* Prequeue for VJ style copy to user, combined with checksumming. */
954
955static inline void tcp_prequeue_init(struct tcp_sock *tp)
956{
957 tp->ucopy.task = NULL;
958 tp->ucopy.len = 0;
959 tp->ucopy.memory = 0;
960 skb_queue_head_init(&tp->ucopy.prequeue);
961#ifdef CONFIG_NET_DMA
962 tp->ucopy.dma_chan = NULL;
963 tp->ucopy.wakeup = 0;
964 tp->ucopy.pinned_list = NULL;
965 tp->ucopy.dma_cookie = 0;
966#endif
967}
968
969/* Packet is added to VJ-style prequeue for processing in process
970 * context, if a reader task is waiting. Apparently, this exciting
971 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
972 * failed somewhere. Latency? Burstiness? Well, at least now we will
973 * see, why it failed. 8)8) --ANK
974 *
975 * NOTE: is this not too big to inline?
976 */
977static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
978{
979 struct tcp_sock *tp = tcp_sk(sk);
980
981 if (sysctl_tcp_low_latency || !tp->ucopy.task)
982 return false;
983
984 __skb_queue_tail(&tp->ucopy.prequeue, skb);
985 tp->ucopy.memory += skb->truesize;
986 if (tp->ucopy.memory > sk->sk_rcvbuf) {
987 struct sk_buff *skb1;
988
989 BUG_ON(sock_owned_by_user(sk));
990
991 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
992 sk_backlog_rcv(sk, skb1);
993 NET_INC_STATS_BH(sock_net(sk),
994 LINUX_MIB_TCPPREQUEUEDROPPED);
995 }
996
997 tp->ucopy.memory = 0;
998 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
999 wake_up_interruptible_sync_poll(sk_sleep(sk),
1000 POLLIN | POLLRDNORM | POLLRDBAND);
1001 if (!inet_csk_ack_scheduled(sk))
1002 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1003 (3 * tcp_rto_min(sk)) / 4,
1004 TCP_RTO_MAX);
1005 }
1006 return true;
1007}
1008
1009
1010#undef STATE_TRACE
1011
1012#ifdef STATE_TRACE
1013static const char *statename[]={
1014 "Unused","Established","Syn Sent","Syn Recv",
1015 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1016 "Close Wait","Last ACK","Listen","Closing"
1017};
1018#endif
1019extern void tcp_set_state(struct sock *sk, int state);
1020
1021extern void tcp_done(struct sock *sk);
1022
1023static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1024{
1025 rx_opt->dsack = 0;
1026 rx_opt->num_sacks = 0;
1027}
1028
1029/* Determine a window scaling and initial window to offer. */
1030extern void tcp_select_initial_window(int __space, __u32 mss,
1031 __u32 *rcv_wnd, __u32 *window_clamp,
1032 int wscale_ok, __u8 *rcv_wscale,
1033 __u32 init_rcv_wnd);
1034
1035static inline int tcp_win_from_space(int space)
1036{
1037 return sysctl_tcp_adv_win_scale<=0 ?
1038 (space>>(-sysctl_tcp_adv_win_scale)) :
1039 space - (space>>sysctl_tcp_adv_win_scale);
1040}
1041
1042/* Note: caller must be prepared to deal with negative returns */
1043static inline int tcp_space(const struct sock *sk)
1044{
1045 return tcp_win_from_space(sk->sk_rcvbuf -
1046 atomic_read(&sk->sk_rmem_alloc));
1047}
1048
1049static inline int tcp_full_space(const struct sock *sk)
1050{
1051 return tcp_win_from_space(sk->sk_rcvbuf);
1052}
1053
1054static inline void tcp_openreq_init(struct request_sock *req,
1055 struct tcp_options_received *rx_opt,
1056 struct sk_buff *skb)
1057{
1058 struct inet_request_sock *ireq = inet_rsk(req);
1059
1060 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1061 req->cookie_ts = 0;
1062 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1063 req->mss = rx_opt->mss_clamp;
1064 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1065 ireq->tstamp_ok = rx_opt->tstamp_ok;
1066 ireq->sack_ok = rx_opt->sack_ok;
1067 ireq->snd_wscale = rx_opt->snd_wscale;
1068 ireq->wscale_ok = rx_opt->wscale_ok;
1069 ireq->acked = 0;
1070 ireq->ecn_ok = 0;
1071 ireq->rmt_port = tcp_hdr(skb)->source;
1072 ireq->loc_port = tcp_hdr(skb)->dest;
1073}
1074
1075extern void tcp_enter_memory_pressure(struct sock *sk);
1076
1077static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1078{
1079 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1080}
1081
1082static inline int keepalive_time_when(const struct tcp_sock *tp)
1083{
1084 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1085}
1086
1087static inline int keepalive_probes(const struct tcp_sock *tp)
1088{
1089 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1090}
1091
1092static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1093{
1094 const struct inet_connection_sock *icsk = &tp->inet_conn;
1095
1096 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1097 tcp_time_stamp - tp->rcv_tstamp);
1098}
1099
1100static inline int tcp_fin_time(const struct sock *sk)
1101{
1102 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1103 const int rto = inet_csk(sk)->icsk_rto;
1104
1105 if (fin_timeout < (rto << 2) - (rto >> 1))
1106 fin_timeout = (rto << 2) - (rto >> 1);
1107
1108 return fin_timeout;
1109}
1110
1111static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1112 int paws_win)
1113{
1114 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1115 return true;
1116 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1117 return true;
1118 /*
1119 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1120 * then following tcp messages have valid values. Ignore 0 value,
1121 * or else 'negative' tsval might forbid us to accept their packets.
1122 */
1123 if (!rx_opt->ts_recent)
1124 return true;
1125 return false;
1126}
1127
1128static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1129 int rst)
1130{
1131 if (tcp_paws_check(rx_opt, 0))
1132 return false;
1133
1134 /* RST segments are not recommended to carry timestamp,
1135 and, if they do, it is recommended to ignore PAWS because
1136 "their cleanup function should take precedence over timestamps."
1137 Certainly, it is mistake. It is necessary to understand the reasons
1138 of this constraint to relax it: if peer reboots, clock may go
1139 out-of-sync and half-open connections will not be reset.
1140 Actually, the problem would be not existing if all
1141 the implementations followed draft about maintaining clock
1142 via reboots. Linux-2.2 DOES NOT!
1143
1144 However, we can relax time bounds for RST segments to MSL.
1145 */
1146 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1147 return false;
1148 return true;
1149}
1150
1151static inline void tcp_mib_init(struct net *net)
1152{
1153 /* See RFC 2012 */
1154 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1155 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1156 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1157 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1158}
1159
1160/* from STCP */
1161static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1162{
1163 tp->lost_skb_hint = NULL;
1164 tp->scoreboard_skb_hint = NULL;
1165}
1166
1167static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1168{
1169 tcp_clear_retrans_hints_partial(tp);
1170 tp->retransmit_skb_hint = NULL;
1171}
1172
1173/* MD5 Signature */
1174struct crypto_hash;
1175
1176union tcp_md5_addr {
1177 struct in_addr a4;
1178#if IS_ENABLED(CONFIG_IPV6)
1179 struct in6_addr a6;
1180#endif
1181};
1182
1183/* - key database */
1184struct tcp_md5sig_key {
1185 struct hlist_node node;
1186 u8 keylen;
1187 u8 family; /* AF_INET or AF_INET6 */
1188 union tcp_md5_addr addr;
1189 u8 key[TCP_MD5SIG_MAXKEYLEN];
1190 struct rcu_head rcu;
1191};
1192
1193/* - sock block */
1194struct tcp_md5sig_info {
1195 struct hlist_head head;
1196 struct rcu_head rcu;
1197};
1198
1199/* - pseudo header */
1200struct tcp4_pseudohdr {
1201 __be32 saddr;
1202 __be32 daddr;
1203 __u8 pad;
1204 __u8 protocol;
1205 __be16 len;
1206};
1207
1208struct tcp6_pseudohdr {
1209 struct in6_addr saddr;
1210 struct in6_addr daddr;
1211 __be32 len;
1212 __be32 protocol; /* including padding */
1213};
1214
1215union tcp_md5sum_block {
1216 struct tcp4_pseudohdr ip4;
1217#if IS_ENABLED(CONFIG_IPV6)
1218 struct tcp6_pseudohdr ip6;
1219#endif
1220};
1221
1222/* - pool: digest algorithm, hash description and scratch buffer */
1223struct tcp_md5sig_pool {
1224 struct hash_desc md5_desc;
1225 union tcp_md5sum_block md5_blk;
1226};
1227
1228/* - functions */
1229extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1230 const struct sock *sk,
1231 const struct request_sock *req,
1232 const struct sk_buff *skb);
1233extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1234 int family, const u8 *newkey,
1235 u8 newkeylen, gfp_t gfp);
1236extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1237 int family);
1238extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1239 struct sock *addr_sk);
1240
1241#ifdef CONFIG_TCP_MD5SIG
1242extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1243 const union tcp_md5_addr *addr, int family);
1244#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1245#else
1246static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1247 const union tcp_md5_addr *addr,
1248 int family)
1249{
1250 return NULL;
1251}
1252#define tcp_twsk_md5_key(twsk) NULL
1253#endif
1254
1255extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1256extern void tcp_free_md5sig_pool(void);
1257
1258extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1259extern void tcp_put_md5sig_pool(void);
1260
1261extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1262extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1263 unsigned int header_len);
1264extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1265 const struct tcp_md5sig_key *key);
1266
1267/* write queue abstraction */
1268static inline void tcp_write_queue_purge(struct sock *sk)
1269{
1270 struct sk_buff *skb;
1271
1272 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1273 sk_wmem_free_skb(sk, skb);
1274 sk_mem_reclaim(sk);
1275 tcp_clear_all_retrans_hints(tcp_sk(sk));
1276}
1277
1278static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1279{
1280 return skb_peek(&sk->sk_write_queue);
1281}
1282
1283static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1284{
1285 return skb_peek_tail(&sk->sk_write_queue);
1286}
1287
1288static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1289 const struct sk_buff *skb)
1290{
1291 return skb_queue_next(&sk->sk_write_queue, skb);
1292}
1293
1294static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1295 const struct sk_buff *skb)
1296{
1297 return skb_queue_prev(&sk->sk_write_queue, skb);
1298}
1299
1300#define tcp_for_write_queue(skb, sk) \
1301 skb_queue_walk(&(sk)->sk_write_queue, skb)
1302
1303#define tcp_for_write_queue_from(skb, sk) \
1304 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1305
1306#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1307 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1308
1309static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1310{
1311 return sk->sk_send_head;
1312}
1313
1314static inline bool tcp_skb_is_last(const struct sock *sk,
1315 const struct sk_buff *skb)
1316{
1317 return skb_queue_is_last(&sk->sk_write_queue, skb);
1318}
1319
1320static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1321{
1322 if (tcp_skb_is_last(sk, skb))
1323 sk->sk_send_head = NULL;
1324 else
1325 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1326}
1327
1328static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1329{
1330 if (sk->sk_send_head == skb_unlinked)
1331 sk->sk_send_head = NULL;
1332}
1333
1334static inline void tcp_init_send_head(struct sock *sk)
1335{
1336 sk->sk_send_head = NULL;
1337}
1338
1339static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1340{
1341 __skb_queue_tail(&sk->sk_write_queue, skb);
1342}
1343
1344static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1345{
1346 __tcp_add_write_queue_tail(sk, skb);
1347
1348 /* Queue it, remembering where we must start sending. */
1349 if (sk->sk_send_head == NULL) {
1350 sk->sk_send_head = skb;
1351
1352 if (tcp_sk(sk)->highest_sack == NULL)
1353 tcp_sk(sk)->highest_sack = skb;
1354 }
1355}
1356
1357static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1358{
1359 __skb_queue_head(&sk->sk_write_queue, skb);
1360}
1361
1362/* Insert buff after skb on the write queue of sk. */
1363static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1364 struct sk_buff *buff,
1365 struct sock *sk)
1366{
1367 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1368}
1369
1370/* Insert new before skb on the write queue of sk. */
1371static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1372 struct sk_buff *skb,
1373 struct sock *sk)
1374{
1375 __skb_queue_before(&sk->sk_write_queue, skb, new);
1376
1377 if (sk->sk_send_head == skb)
1378 sk->sk_send_head = new;
1379}
1380
1381static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1382{
1383 __skb_unlink(skb, &sk->sk_write_queue);
1384}
1385
1386static inline bool tcp_write_queue_empty(struct sock *sk)
1387{
1388 return skb_queue_empty(&sk->sk_write_queue);
1389}
1390
1391static inline void tcp_push_pending_frames(struct sock *sk)
1392{
1393 if (tcp_send_head(sk)) {
1394 struct tcp_sock *tp = tcp_sk(sk);
1395
1396 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1397 }
1398}
1399
1400/* Start sequence of the skb just after the highest skb with SACKed
1401 * bit, valid only if sacked_out > 0 or when the caller has ensured
1402 * validity by itself.
1403 */
1404static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1405{
1406 if (!tp->sacked_out)
1407 return tp->snd_una;
1408
1409 if (tp->highest_sack == NULL)
1410 return tp->snd_nxt;
1411
1412 return TCP_SKB_CB(tp->highest_sack)->seq;
1413}
1414
1415static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1416{
1417 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1418 tcp_write_queue_next(sk, skb);
1419}
1420
1421static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1422{
1423 return tcp_sk(sk)->highest_sack;
1424}
1425
1426static inline void tcp_highest_sack_reset(struct sock *sk)
1427{
1428 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1429}
1430
1431/* Called when old skb is about to be deleted (to be combined with new skb) */
1432static inline void tcp_highest_sack_combine(struct sock *sk,
1433 struct sk_buff *old,
1434 struct sk_buff *new)
1435{
1436 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1437 tcp_sk(sk)->highest_sack = new;
1438}
1439
1440/* Determines whether this is a thin stream (which may suffer from
1441 * increased latency). Used to trigger latency-reducing mechanisms.
1442 */
1443static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1444{
1445 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1446}
1447
1448/* /proc */
1449enum tcp_seq_states {
1450 TCP_SEQ_STATE_LISTENING,
1451 TCP_SEQ_STATE_OPENREQ,
1452 TCP_SEQ_STATE_ESTABLISHED,
1453 TCP_SEQ_STATE_TIME_WAIT,
1454};
1455
1456int tcp_seq_open(struct inode *inode, struct file *file);
1457
1458struct tcp_seq_afinfo {
1459 char *name;
1460 sa_family_t family;
1461 const struct file_operations *seq_fops;
1462 struct seq_operations seq_ops;
1463};
1464
1465struct tcp_iter_state {
1466 struct seq_net_private p;
1467 sa_family_t family;
1468 enum tcp_seq_states state;
1469 struct sock *syn_wait_sk;
1470 int bucket, offset, sbucket, num, uid;
1471 loff_t last_pos;
1472};
1473
1474extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1475extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1476
1477extern struct request_sock_ops tcp_request_sock_ops;
1478extern struct request_sock_ops tcp6_request_sock_ops;
1479
1480extern void tcp_v4_destroy_sock(struct sock *sk);
1481
1482extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1483extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1484 netdev_features_t features);
1485extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1486 struct sk_buff *skb);
1487extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1488 struct sk_buff *skb);
1489extern int tcp_gro_complete(struct sk_buff *skb);
1490extern int tcp4_gro_complete(struct sk_buff *skb);
1491
1492#ifdef CONFIG_PROC_FS
1493extern int tcp4_proc_init(void);
1494extern void tcp4_proc_exit(void);
1495#endif
1496
1497/* TCP af-specific functions */
1498struct tcp_sock_af_ops {
1499#ifdef CONFIG_TCP_MD5SIG
1500 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1501 struct sock *addr_sk);
1502 int (*calc_md5_hash) (char *location,
1503 struct tcp_md5sig_key *md5,
1504 const struct sock *sk,
1505 const struct request_sock *req,
1506 const struct sk_buff *skb);
1507 int (*md5_parse) (struct sock *sk,
1508 char __user *optval,
1509 int optlen);
1510#endif
1511};
1512
1513struct tcp_request_sock_ops {
1514#ifdef CONFIG_TCP_MD5SIG
1515 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1516 struct request_sock *req);
1517 int (*calc_md5_hash) (char *location,
1518 struct tcp_md5sig_key *md5,
1519 const struct sock *sk,
1520 const struct request_sock *req,
1521 const struct sk_buff *skb);
1522#endif
1523};
1524
1525/* Using SHA1 for now, define some constants.
1526 */
1527#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1528#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1529#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1530
1531extern int tcp_cookie_generator(u32 *bakery);
1532
1533/**
1534 * struct tcp_cookie_values - each socket needs extra space for the
1535 * cookies, together with (optional) space for any SYN data.
1536 *
1537 * A tcp_sock contains a pointer to the current value, and this is
1538 * cloned to the tcp_timewait_sock.
1539 *
1540 * @cookie_pair: variable data from the option exchange.
1541 *
1542 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1543 * indicates default (sysctl_tcp_cookie_size).
1544 * After cookie sent, remembers size of cookie.
1545 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1546 *
1547 * @s_data_desired: user specified tcpct_s_data_desired. When the
1548 * constant payload is specified (@s_data_constant),
1549 * holds its length instead.
1550 * Range 0 to TCP_MSS_DESIRED.
1551 *
1552 * @s_data_payload: constant data that is to be included in the
1553 * payload of SYN or SYNACK segments when the
1554 * cookie option is present.
1555 */
1556struct tcp_cookie_values {
1557 struct kref kref;
1558 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1559 u8 cookie_pair_size;
1560 u8 cookie_desired;
1561 u16 s_data_desired:11,
1562 s_data_constant:1,
1563 s_data_in:1,
1564 s_data_out:1,
1565 s_data_unused:2;
1566 u8 s_data_payload[0];
1567};
1568
1569static inline void tcp_cookie_values_release(struct kref *kref)
1570{
1571 kfree(container_of(kref, struct tcp_cookie_values, kref));
1572}
1573
1574/* The length of constant payload data. Note that s_data_desired is
1575 * overloaded, depending on s_data_constant: either the length of constant
1576 * data (returned here) or the limit on variable data.
1577 */
1578static inline int tcp_s_data_size(const struct tcp_sock *tp)
1579{
1580 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1581 ? tp->cookie_values->s_data_desired
1582 : 0;
1583}
1584
1585/**
1586 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1587 *
1588 * As tcp_request_sock has already been extended in other places, the
1589 * only remaining method is to pass stack values along as function
1590 * parameters. These parameters are not needed after sending SYNACK.
1591 *
1592 * @cookie_bakery: cryptographic secret and message workspace.
1593 *
1594 * @cookie_plus: bytes in authenticator/cookie option, copied from
1595 * struct tcp_options_received (above).
1596 */
1597struct tcp_extend_values {
1598 struct request_values rv;
1599 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1600 u8 cookie_plus:6,
1601 cookie_out_never:1,
1602 cookie_in_always:1;
1603};
1604
1605static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1606{
1607 return (struct tcp_extend_values *)rvp;
1608}
1609
1610extern void tcp_v4_init(void);
1611extern void tcp_init(void);
1612
1613#endif /* _TCP_H */