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1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define FASTRETRANS_DEBUG 1
22
23#include <linux/list.h>
24#include <linux/tcp.h>
25#include <linux/bug.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
29#include <linux/skbuff.h>
30#include <linux/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 6 /* This is how many retries are done
102 * when active opening a connection.
103 * RFC1122 says the minimum retry MUST
104 * be at least 180secs. Nevertheless
105 * this value is corresponding to
106 * 63secs of retransmission with the
107 * current initial RTO.
108 */
109
110#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
111 * when passive opening a connection.
112 * This is corresponding to 31secs of
113 * retransmission with the current
114 * initial RTO.
115 */
116
117#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
118 * state, about 60 seconds */
119#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
120 /* BSD style FIN_WAIT2 deadlock breaker.
121 * It used to be 3min, new value is 60sec,
122 * to combine FIN-WAIT-2 timeout with
123 * TIME-WAIT timer.
124 */
125
126#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
127#if HZ >= 100
128#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
129#define TCP_ATO_MIN ((unsigned)(HZ/25))
130#else
131#define TCP_DELACK_MIN 4U
132#define TCP_ATO_MIN 4U
133#endif
134#define TCP_RTO_MAX ((unsigned)(120*HZ))
135#define TCP_RTO_MIN ((unsigned)(HZ/5))
136#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
137#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
138 * used as a fallback RTO for the
139 * initial data transmission if no
140 * valid RTT sample has been acquired,
141 * most likely due to retrans in 3WHS.
142 */
143
144#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
145 * for local resources.
146 */
147
148#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
149#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
150#define TCP_KEEPALIVE_INTVL (75*HZ)
151
152#define MAX_TCP_KEEPIDLE 32767
153#define MAX_TCP_KEEPINTVL 32767
154#define MAX_TCP_KEEPCNT 127
155#define MAX_TCP_SYNCNT 127
156
157#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
158
159#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
160#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
161 * after this time. It should be equal
162 * (or greater than) TCP_TIMEWAIT_LEN
163 * to provide reliability equal to one
164 * provided by timewait state.
165 */
166#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
167 * timestamps. It must be less than
168 * minimal timewait lifetime.
169 */
170/*
171 * TCP option
172 */
173
174#define TCPOPT_NOP 1 /* Padding */
175#define TCPOPT_EOL 0 /* End of options */
176#define TCPOPT_MSS 2 /* Segment size negotiating */
177#define TCPOPT_WINDOW 3 /* Window scaling */
178#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
179#define TCPOPT_SACK 5 /* SACK Block */
180#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
181#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
182#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
183#define TCPOPT_EXP 254 /* Experimental */
184/* Magic number to be after the option value for sharing TCP
185 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
186 */
187#define TCPOPT_FASTOPEN_MAGIC 0xF989
188
189/*
190 * TCP option lengths
191 */
192
193#define TCPOLEN_MSS 4
194#define TCPOLEN_WINDOW 3
195#define TCPOLEN_SACK_PERM 2
196#define TCPOLEN_TIMESTAMP 10
197#define TCPOLEN_MD5SIG 18
198#define TCPOLEN_EXP_FASTOPEN_BASE 4
199#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
200#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
201#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
202#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
203
204/* But this is what stacks really send out. */
205#define TCPOLEN_TSTAMP_ALIGNED 12
206#define TCPOLEN_WSCALE_ALIGNED 4
207#define TCPOLEN_SACKPERM_ALIGNED 4
208#define TCPOLEN_SACK_BASE 2
209#define TCPOLEN_SACK_BASE_ALIGNED 4
210#define TCPOLEN_SACK_PERBLOCK 8
211#define TCPOLEN_MD5SIG_ALIGNED 20
212#define TCPOLEN_MSS_ALIGNED 4
213
214/* Flags in tp->nonagle */
215#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
216#define TCP_NAGLE_CORK 2 /* Socket is corked */
217#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
218
219/* TCP thin-stream limits */
220#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
221
222/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
223#define TCP_INIT_CWND 10
224
225/* Bit Flags for sysctl_tcp_fastopen */
226#define TFO_CLIENT_ENABLE 1
227#define TFO_SERVER_ENABLE 2
228#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
229
230/* Process SYN data but skip cookie validation */
231#define TFO_SERVER_COOKIE_NOT_CHKED 0x100
232/* Accept SYN data w/o any cookie option */
233#define TFO_SERVER_COOKIE_NOT_REQD 0x200
234
235/* Force enable TFO on all listeners, i.e., not requiring the
236 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
237 */
238#define TFO_SERVER_WO_SOCKOPT1 0x400
239#define TFO_SERVER_WO_SOCKOPT2 0x800
240/* Always create TFO child sockets on a TFO listener even when
241 * cookie/data not present. (For testing purpose!)
242 */
243#define TFO_SERVER_ALWAYS 0x1000
244
245extern struct inet_timewait_death_row tcp_death_row;
246
247/* sysctl variables for tcp */
248extern int sysctl_tcp_timestamps;
249extern int sysctl_tcp_window_scaling;
250extern int sysctl_tcp_sack;
251extern int sysctl_tcp_fin_timeout;
252extern int sysctl_tcp_keepalive_time;
253extern int sysctl_tcp_keepalive_probes;
254extern int sysctl_tcp_keepalive_intvl;
255extern int sysctl_tcp_syn_retries;
256extern int sysctl_tcp_synack_retries;
257extern int sysctl_tcp_retries1;
258extern int sysctl_tcp_retries2;
259extern int sysctl_tcp_orphan_retries;
260extern int sysctl_tcp_syncookies;
261extern int sysctl_tcp_fastopen;
262extern int sysctl_tcp_retrans_collapse;
263extern int sysctl_tcp_stdurg;
264extern int sysctl_tcp_rfc1337;
265extern int sysctl_tcp_abort_on_overflow;
266extern int sysctl_tcp_max_orphans;
267extern int sysctl_tcp_fack;
268extern int sysctl_tcp_reordering;
269extern int sysctl_tcp_ecn;
270extern int sysctl_tcp_dsack;
271extern int sysctl_tcp_wmem[3];
272extern int sysctl_tcp_rmem[3];
273extern int sysctl_tcp_app_win;
274extern int sysctl_tcp_adv_win_scale;
275extern int sysctl_tcp_tw_reuse;
276extern int sysctl_tcp_frto;
277extern int sysctl_tcp_frto_response;
278extern int sysctl_tcp_low_latency;
279extern int sysctl_tcp_dma_copybreak;
280extern int sysctl_tcp_nometrics_save;
281extern int sysctl_tcp_moderate_rcvbuf;
282extern int sysctl_tcp_tso_win_divisor;
283extern int sysctl_tcp_abc;
284extern int sysctl_tcp_mtu_probing;
285extern int sysctl_tcp_base_mss;
286extern int sysctl_tcp_workaround_signed_windows;
287extern int sysctl_tcp_slow_start_after_idle;
288extern int sysctl_tcp_max_ssthresh;
289extern int sysctl_tcp_cookie_size;
290extern int sysctl_tcp_thin_linear_timeouts;
291extern int sysctl_tcp_thin_dupack;
292extern int sysctl_tcp_early_retrans;
293extern int sysctl_tcp_limit_output_bytes;
294extern int sysctl_tcp_challenge_ack_limit;
295
296extern atomic_long_t tcp_memory_allocated;
297extern struct percpu_counter tcp_sockets_allocated;
298extern int tcp_memory_pressure;
299
300/*
301 * The next routines deal with comparing 32 bit unsigned ints
302 * and worry about wraparound (automatic with unsigned arithmetic).
303 */
304
305static inline bool before(__u32 seq1, __u32 seq2)
306{
307 return (__s32)(seq1-seq2) < 0;
308}
309#define after(seq2, seq1) before(seq1, seq2)
310
311/* is s2<=s1<=s3 ? */
312static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
313{
314 return seq3 - seq2 >= seq1 - seq2;
315}
316
317static inline bool tcp_out_of_memory(struct sock *sk)
318{
319 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
320 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
321 return true;
322 return false;
323}
324
325static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
326{
327 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
328 int orphans = percpu_counter_read_positive(ocp);
329
330 if (orphans << shift > sysctl_tcp_max_orphans) {
331 orphans = percpu_counter_sum_positive(ocp);
332 if (orphans << shift > sysctl_tcp_max_orphans)
333 return true;
334 }
335 return false;
336}
337
338extern bool tcp_check_oom(struct sock *sk, int shift);
339
340/* syncookies: remember time of last synqueue overflow */
341static inline void tcp_synq_overflow(struct sock *sk)
342{
343 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
344}
345
346/* syncookies: no recent synqueue overflow on this listening socket? */
347static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
348{
349 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
350 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
351}
352
353extern struct proto tcp_prot;
354
355#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
356#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
357#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
358#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
359#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
360
361extern void tcp_init_mem(struct net *net);
362
363extern void tcp_tasklet_init(void);
364
365extern void tcp_v4_err(struct sk_buff *skb, u32);
366
367extern void tcp_shutdown (struct sock *sk, int how);
368
369extern void tcp_v4_early_demux(struct sk_buff *skb);
370extern int tcp_v4_rcv(struct sk_buff *skb);
371
372extern struct inet_peer *tcp_v4_get_peer(struct sock *sk);
373extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
374extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
375 size_t size);
376extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
377 size_t size, int flags);
378extern void tcp_release_cb(struct sock *sk);
379extern void tcp_write_timer_handler(struct sock *sk);
380extern void tcp_delack_timer_handler(struct sock *sk);
381extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
382extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
383 const struct tcphdr *th, unsigned int len);
384extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
385 const struct tcphdr *th, unsigned int len);
386extern void tcp_rcv_space_adjust(struct sock *sk);
387extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
388extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
389extern void tcp_twsk_destructor(struct sock *sk);
390extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
391 struct pipe_inode_info *pipe, size_t len,
392 unsigned int flags);
393
394static inline void tcp_dec_quickack_mode(struct sock *sk,
395 const unsigned int pkts)
396{
397 struct inet_connection_sock *icsk = inet_csk(sk);
398
399 if (icsk->icsk_ack.quick) {
400 if (pkts >= icsk->icsk_ack.quick) {
401 icsk->icsk_ack.quick = 0;
402 /* Leaving quickack mode we deflate ATO. */
403 icsk->icsk_ack.ato = TCP_ATO_MIN;
404 } else
405 icsk->icsk_ack.quick -= pkts;
406 }
407}
408
409#define TCP_ECN_OK 1
410#define TCP_ECN_QUEUE_CWR 2
411#define TCP_ECN_DEMAND_CWR 4
412#define TCP_ECN_SEEN 8
413
414enum tcp_tw_status {
415 TCP_TW_SUCCESS = 0,
416 TCP_TW_RST = 1,
417 TCP_TW_ACK = 2,
418 TCP_TW_SYN = 3
419};
420
421
422extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
423 struct sk_buff *skb,
424 const struct tcphdr *th);
425extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
426 struct request_sock *req,
427 struct request_sock **prev,
428 bool fastopen);
429extern int tcp_child_process(struct sock *parent, struct sock *child,
430 struct sk_buff *skb);
431extern bool tcp_use_frto(struct sock *sk);
432extern void tcp_enter_frto(struct sock *sk);
433extern void tcp_enter_loss(struct sock *sk, int how);
434extern void tcp_clear_retrans(struct tcp_sock *tp);
435extern void tcp_update_metrics(struct sock *sk);
436extern void tcp_init_metrics(struct sock *sk);
437extern void tcp_metrics_init(void);
438extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
439extern bool tcp_remember_stamp(struct sock *sk);
440extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
441extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
442extern void tcp_disable_fack(struct tcp_sock *tp);
443extern void tcp_close(struct sock *sk, long timeout);
444extern void tcp_init_sock(struct sock *sk);
445extern unsigned int tcp_poll(struct file * file, struct socket *sock,
446 struct poll_table_struct *wait);
447extern int tcp_getsockopt(struct sock *sk, int level, int optname,
448 char __user *optval, int __user *optlen);
449extern int tcp_setsockopt(struct sock *sk, int level, int optname,
450 char __user *optval, unsigned int optlen);
451extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
452 char __user *optval, int __user *optlen);
453extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
454 char __user *optval, unsigned int optlen);
455extern void tcp_set_keepalive(struct sock *sk, int val);
456extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
457extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
458 size_t len, int nonblock, int flags, int *addr_len);
459extern void tcp_parse_options(const struct sk_buff *skb,
460 struct tcp_options_received *opt_rx, const u8 **hvpp,
461 int estab, struct tcp_fastopen_cookie *foc);
462extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
463
464/*
465 * TCP v4 functions exported for the inet6 API
466 */
467
468extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
469extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
470extern struct sock * tcp_create_openreq_child(struct sock *sk,
471 struct request_sock *req,
472 struct sk_buff *skb);
473extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
474 struct request_sock *req,
475 struct dst_entry *dst);
476extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
477extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
478 int addr_len);
479extern int tcp_connect(struct sock *sk);
480extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
481 struct request_sock *req,
482 struct request_values *rvp,
483 struct tcp_fastopen_cookie *foc);
484extern int tcp_disconnect(struct sock *sk, int flags);
485
486void tcp_connect_init(struct sock *sk);
487void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
488int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
489void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
490
491/* From syncookies.c */
492extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
493extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
494 struct ip_options *opt);
495#ifdef CONFIG_SYN_COOKIES
496extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
497 __u16 *mss);
498#else
499static inline __u32 cookie_v4_init_sequence(struct sock *sk,
500 struct sk_buff *skb,
501 __u16 *mss)
502{
503 return 0;
504}
505#endif
506
507extern __u32 cookie_init_timestamp(struct request_sock *req);
508extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
509
510/* From net/ipv6/syncookies.c */
511extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
512#ifdef CONFIG_SYN_COOKIES
513extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
514 __u16 *mss);
515#else
516static inline __u32 cookie_v6_init_sequence(struct sock *sk,
517 struct sk_buff *skb,
518 __u16 *mss)
519{
520 return 0;
521}
522#endif
523/* tcp_output.c */
524
525extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
526 int nonagle);
527extern bool tcp_may_send_now(struct sock *sk);
528extern int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
529extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
530extern void tcp_retransmit_timer(struct sock *sk);
531extern void tcp_xmit_retransmit_queue(struct sock *);
532extern void tcp_simple_retransmit(struct sock *);
533extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
534extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
535
536extern void tcp_send_probe0(struct sock *);
537extern void tcp_send_partial(struct sock *);
538extern int tcp_write_wakeup(struct sock *);
539extern void tcp_send_fin(struct sock *sk);
540extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
541extern int tcp_send_synack(struct sock *);
542extern bool tcp_syn_flood_action(struct sock *sk,
543 const struct sk_buff *skb,
544 const char *proto);
545extern void tcp_push_one(struct sock *, unsigned int mss_now);
546extern void tcp_send_ack(struct sock *sk);
547extern void tcp_send_delayed_ack(struct sock *sk);
548
549/* tcp_input.c */
550extern void tcp_cwnd_application_limited(struct sock *sk);
551extern void tcp_resume_early_retransmit(struct sock *sk);
552extern void tcp_rearm_rto(struct sock *sk);
553extern void tcp_reset(struct sock *sk);
554
555/* tcp_timer.c */
556extern void tcp_init_xmit_timers(struct sock *);
557static inline void tcp_clear_xmit_timers(struct sock *sk)
558{
559 inet_csk_clear_xmit_timers(sk);
560}
561
562extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
563extern unsigned int tcp_current_mss(struct sock *sk);
564
565/* Bound MSS / TSO packet size with the half of the window */
566static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
567{
568 int cutoff;
569
570 /* When peer uses tiny windows, there is no use in packetizing
571 * to sub-MSS pieces for the sake of SWS or making sure there
572 * are enough packets in the pipe for fast recovery.
573 *
574 * On the other hand, for extremely large MSS devices, handling
575 * smaller than MSS windows in this way does make sense.
576 */
577 if (tp->max_window >= 512)
578 cutoff = (tp->max_window >> 1);
579 else
580 cutoff = tp->max_window;
581
582 if (cutoff && pktsize > cutoff)
583 return max_t(int, cutoff, 68U - tp->tcp_header_len);
584 else
585 return pktsize;
586}
587
588/* tcp.c */
589extern void tcp_get_info(const struct sock *, struct tcp_info *);
590
591/* Read 'sendfile()'-style from a TCP socket */
592typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
593 unsigned int, size_t);
594extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
595 sk_read_actor_t recv_actor);
596
597extern void tcp_initialize_rcv_mss(struct sock *sk);
598
599extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
600extern int tcp_mss_to_mtu(struct sock *sk, int mss);
601extern void tcp_mtup_init(struct sock *sk);
602extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
603extern void tcp_init_buffer_space(struct sock *sk);
604
605static inline void tcp_bound_rto(const struct sock *sk)
606{
607 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
608 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
609}
610
611static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
612{
613 return (tp->srtt >> 3) + tp->rttvar;
614}
615
616extern void tcp_set_rto(struct sock *sk);
617
618static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
619{
620 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
621 ntohl(TCP_FLAG_ACK) |
622 snd_wnd);
623}
624
625static inline void tcp_fast_path_on(struct tcp_sock *tp)
626{
627 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
628}
629
630static inline void tcp_fast_path_check(struct sock *sk)
631{
632 struct tcp_sock *tp = tcp_sk(sk);
633
634 if (skb_queue_empty(&tp->out_of_order_queue) &&
635 tp->rcv_wnd &&
636 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
637 !tp->urg_data)
638 tcp_fast_path_on(tp);
639}
640
641/* Compute the actual rto_min value */
642static inline u32 tcp_rto_min(struct sock *sk)
643{
644 const struct dst_entry *dst = __sk_dst_get(sk);
645 u32 rto_min = TCP_RTO_MIN;
646
647 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
648 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
649 return rto_min;
650}
651
652/* Compute the actual receive window we are currently advertising.
653 * Rcv_nxt can be after the window if our peer push more data
654 * than the offered window.
655 */
656static inline u32 tcp_receive_window(const struct tcp_sock *tp)
657{
658 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
659
660 if (win < 0)
661 win = 0;
662 return (u32) win;
663}
664
665/* Choose a new window, without checks for shrinking, and without
666 * scaling applied to the result. The caller does these things
667 * if necessary. This is a "raw" window selection.
668 */
669extern u32 __tcp_select_window(struct sock *sk);
670
671void tcp_send_window_probe(struct sock *sk);
672
673/* TCP timestamps are only 32-bits, this causes a slight
674 * complication on 64-bit systems since we store a snapshot
675 * of jiffies in the buffer control blocks below. We decided
676 * to use only the low 32-bits of jiffies and hide the ugly
677 * casts with the following macro.
678 */
679#define tcp_time_stamp ((__u32)(jiffies))
680
681#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
682
683#define TCPHDR_FIN 0x01
684#define TCPHDR_SYN 0x02
685#define TCPHDR_RST 0x04
686#define TCPHDR_PSH 0x08
687#define TCPHDR_ACK 0x10
688#define TCPHDR_URG 0x20
689#define TCPHDR_ECE 0x40
690#define TCPHDR_CWR 0x80
691
692/* This is what the send packet queuing engine uses to pass
693 * TCP per-packet control information to the transmission code.
694 * We also store the host-order sequence numbers in here too.
695 * This is 44 bytes if IPV6 is enabled.
696 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
697 */
698struct tcp_skb_cb {
699 union {
700 struct inet_skb_parm h4;
701#if IS_ENABLED(CONFIG_IPV6)
702 struct inet6_skb_parm h6;
703#endif
704 } header; /* For incoming frames */
705 __u32 seq; /* Starting sequence number */
706 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
707 __u32 when; /* used to compute rtt's */
708 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
709
710 __u8 sacked; /* State flags for SACK/FACK. */
711#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
712#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
713#define TCPCB_LOST 0x04 /* SKB is lost */
714#define TCPCB_TAGBITS 0x07 /* All tag bits */
715#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
716#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
717
718 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
719 /* 1 byte hole */
720 __u32 ack_seq; /* Sequence number ACK'd */
721};
722
723#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
724
725/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
726 *
727 * If we receive a SYN packet with these bits set, it means a network is
728 * playing bad games with TOS bits. In order to avoid possible false congestion
729 * notifications, we disable TCP ECN negociation.
730 */
731static inline void
732TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb)
733{
734 const struct tcphdr *th = tcp_hdr(skb);
735
736 if (sysctl_tcp_ecn && th->ece && th->cwr &&
737 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
738 inet_rsk(req)->ecn_ok = 1;
739}
740
741/* Due to TSO, an SKB can be composed of multiple actual
742 * packets. To keep these tracked properly, we use this.
743 */
744static inline int tcp_skb_pcount(const struct sk_buff *skb)
745{
746 return skb_shinfo(skb)->gso_segs;
747}
748
749/* This is valid iff tcp_skb_pcount() > 1. */
750static inline int tcp_skb_mss(const struct sk_buff *skb)
751{
752 return skb_shinfo(skb)->gso_size;
753}
754
755/* Events passed to congestion control interface */
756enum tcp_ca_event {
757 CA_EVENT_TX_START, /* first transmit when no packets in flight */
758 CA_EVENT_CWND_RESTART, /* congestion window restart */
759 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
760 CA_EVENT_FRTO, /* fast recovery timeout */
761 CA_EVENT_LOSS, /* loss timeout */
762 CA_EVENT_FAST_ACK, /* in sequence ack */
763 CA_EVENT_SLOW_ACK, /* other ack */
764};
765
766/*
767 * Interface for adding new TCP congestion control handlers
768 */
769#define TCP_CA_NAME_MAX 16
770#define TCP_CA_MAX 128
771#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
772
773#define TCP_CONG_NON_RESTRICTED 0x1
774#define TCP_CONG_RTT_STAMP 0x2
775
776struct tcp_congestion_ops {
777 struct list_head list;
778 unsigned long flags;
779
780 /* initialize private data (optional) */
781 void (*init)(struct sock *sk);
782 /* cleanup private data (optional) */
783 void (*release)(struct sock *sk);
784
785 /* return slow start threshold (required) */
786 u32 (*ssthresh)(struct sock *sk);
787 /* lower bound for congestion window (optional) */
788 u32 (*min_cwnd)(const struct sock *sk);
789 /* do new cwnd calculation (required) */
790 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
791 /* call before changing ca_state (optional) */
792 void (*set_state)(struct sock *sk, u8 new_state);
793 /* call when cwnd event occurs (optional) */
794 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
795 /* new value of cwnd after loss (optional) */
796 u32 (*undo_cwnd)(struct sock *sk);
797 /* hook for packet ack accounting (optional) */
798 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
799 /* get info for inet_diag (optional) */
800 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
801
802 char name[TCP_CA_NAME_MAX];
803 struct module *owner;
804};
805
806extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
807extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
808
809extern void tcp_init_congestion_control(struct sock *sk);
810extern void tcp_cleanup_congestion_control(struct sock *sk);
811extern int tcp_set_default_congestion_control(const char *name);
812extern void tcp_get_default_congestion_control(char *name);
813extern void tcp_get_available_congestion_control(char *buf, size_t len);
814extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
815extern int tcp_set_allowed_congestion_control(char *allowed);
816extern int tcp_set_congestion_control(struct sock *sk, const char *name);
817extern void tcp_slow_start(struct tcp_sock *tp);
818extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
819
820extern struct tcp_congestion_ops tcp_init_congestion_ops;
821extern u32 tcp_reno_ssthresh(struct sock *sk);
822extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
823extern u32 tcp_reno_min_cwnd(const struct sock *sk);
824extern struct tcp_congestion_ops tcp_reno;
825
826static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
827{
828 struct inet_connection_sock *icsk = inet_csk(sk);
829
830 if (icsk->icsk_ca_ops->set_state)
831 icsk->icsk_ca_ops->set_state(sk, ca_state);
832 icsk->icsk_ca_state = ca_state;
833}
834
835static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
836{
837 const struct inet_connection_sock *icsk = inet_csk(sk);
838
839 if (icsk->icsk_ca_ops->cwnd_event)
840 icsk->icsk_ca_ops->cwnd_event(sk, event);
841}
842
843/* These functions determine how the current flow behaves in respect of SACK
844 * handling. SACK is negotiated with the peer, and therefore it can vary
845 * between different flows.
846 *
847 * tcp_is_sack - SACK enabled
848 * tcp_is_reno - No SACK
849 * tcp_is_fack - FACK enabled, implies SACK enabled
850 */
851static inline int tcp_is_sack(const struct tcp_sock *tp)
852{
853 return tp->rx_opt.sack_ok;
854}
855
856static inline bool tcp_is_reno(const struct tcp_sock *tp)
857{
858 return !tcp_is_sack(tp);
859}
860
861static inline bool tcp_is_fack(const struct tcp_sock *tp)
862{
863 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
864}
865
866static inline void tcp_enable_fack(struct tcp_sock *tp)
867{
868 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
869}
870
871/* TCP early-retransmit (ER) is similar to but more conservative than
872 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
873 */
874static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
875{
876 tp->do_early_retrans = sysctl_tcp_early_retrans &&
877 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3;
878 tp->early_retrans_delayed = 0;
879}
880
881static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
882{
883 tp->do_early_retrans = 0;
884}
885
886static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
887{
888 return tp->sacked_out + tp->lost_out;
889}
890
891/* This determines how many packets are "in the network" to the best
892 * of our knowledge. In many cases it is conservative, but where
893 * detailed information is available from the receiver (via SACK
894 * blocks etc.) we can make more aggressive calculations.
895 *
896 * Use this for decisions involving congestion control, use just
897 * tp->packets_out to determine if the send queue is empty or not.
898 *
899 * Read this equation as:
900 *
901 * "Packets sent once on transmission queue" MINUS
902 * "Packets left network, but not honestly ACKed yet" PLUS
903 * "Packets fast retransmitted"
904 */
905static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
906{
907 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
908}
909
910#define TCP_INFINITE_SSTHRESH 0x7fffffff
911
912static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
913{
914 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
915}
916
917static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
918{
919 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
920 (1 << inet_csk(sk)->icsk_ca_state);
921}
922
923/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
924 * The exception is cwnd reduction phase, when cwnd is decreasing towards
925 * ssthresh.
926 */
927static inline __u32 tcp_current_ssthresh(const struct sock *sk)
928{
929 const struct tcp_sock *tp = tcp_sk(sk);
930
931 if (tcp_in_cwnd_reduction(sk))
932 return tp->snd_ssthresh;
933 else
934 return max(tp->snd_ssthresh,
935 ((tp->snd_cwnd >> 1) +
936 (tp->snd_cwnd >> 2)));
937}
938
939/* Use define here intentionally to get WARN_ON location shown at the caller */
940#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
941
942extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
943extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
944
945/* The maximum number of MSS of available cwnd for which TSO defers
946 * sending if not using sysctl_tcp_tso_win_divisor.
947 */
948static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
949{
950 return 3;
951}
952
953/* Slow start with delack produces 3 packets of burst, so that
954 * it is safe "de facto". This will be the default - same as
955 * the default reordering threshold - but if reordering increases,
956 * we must be able to allow cwnd to burst at least this much in order
957 * to not pull it back when holes are filled.
958 */
959static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
960{
961 return tp->reordering;
962}
963
964/* Returns end sequence number of the receiver's advertised window */
965static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
966{
967 return tp->snd_una + tp->snd_wnd;
968}
969extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
970
971static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
972 const struct sk_buff *skb)
973{
974 if (skb->len < mss)
975 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
976}
977
978static inline void tcp_check_probe_timer(struct sock *sk)
979{
980 const struct tcp_sock *tp = tcp_sk(sk);
981 const struct inet_connection_sock *icsk = inet_csk(sk);
982
983 if (!tp->packets_out && !icsk->icsk_pending)
984 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
985 icsk->icsk_rto, TCP_RTO_MAX);
986}
987
988static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
989{
990 tp->snd_wl1 = seq;
991}
992
993static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
994{
995 tp->snd_wl1 = seq;
996}
997
998/*
999 * Calculate(/check) TCP checksum
1000 */
1001static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1002 __be32 daddr, __wsum base)
1003{
1004 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1005}
1006
1007static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1008{
1009 return __skb_checksum_complete(skb);
1010}
1011
1012static inline bool tcp_checksum_complete(struct sk_buff *skb)
1013{
1014 return !skb_csum_unnecessary(skb) &&
1015 __tcp_checksum_complete(skb);
1016}
1017
1018/* Prequeue for VJ style copy to user, combined with checksumming. */
1019
1020static inline void tcp_prequeue_init(struct tcp_sock *tp)
1021{
1022 tp->ucopy.task = NULL;
1023 tp->ucopy.len = 0;
1024 tp->ucopy.memory = 0;
1025 skb_queue_head_init(&tp->ucopy.prequeue);
1026#ifdef CONFIG_NET_DMA
1027 tp->ucopy.dma_chan = NULL;
1028 tp->ucopy.wakeup = 0;
1029 tp->ucopy.pinned_list = NULL;
1030 tp->ucopy.dma_cookie = 0;
1031#endif
1032}
1033
1034/* Packet is added to VJ-style prequeue for processing in process
1035 * context, if a reader task is waiting. Apparently, this exciting
1036 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
1037 * failed somewhere. Latency? Burstiness? Well, at least now we will
1038 * see, why it failed. 8)8) --ANK
1039 *
1040 * NOTE: is this not too big to inline?
1041 */
1042static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1043{
1044 struct tcp_sock *tp = tcp_sk(sk);
1045
1046 if (sysctl_tcp_low_latency || !tp->ucopy.task)
1047 return false;
1048
1049 __skb_queue_tail(&tp->ucopy.prequeue, skb);
1050 tp->ucopy.memory += skb->truesize;
1051 if (tp->ucopy.memory > sk->sk_rcvbuf) {
1052 struct sk_buff *skb1;
1053
1054 BUG_ON(sock_owned_by_user(sk));
1055
1056 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1057 sk_backlog_rcv(sk, skb1);
1058 NET_INC_STATS_BH(sock_net(sk),
1059 LINUX_MIB_TCPPREQUEUEDROPPED);
1060 }
1061
1062 tp->ucopy.memory = 0;
1063 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1064 wake_up_interruptible_sync_poll(sk_sleep(sk),
1065 POLLIN | POLLRDNORM | POLLRDBAND);
1066 if (!inet_csk_ack_scheduled(sk))
1067 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1068 (3 * tcp_rto_min(sk)) / 4,
1069 TCP_RTO_MAX);
1070 }
1071 return true;
1072}
1073
1074
1075#undef STATE_TRACE
1076
1077#ifdef STATE_TRACE
1078static const char *statename[]={
1079 "Unused","Established","Syn Sent","Syn Recv",
1080 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1081 "Close Wait","Last ACK","Listen","Closing"
1082};
1083#endif
1084extern void tcp_set_state(struct sock *sk, int state);
1085
1086extern void tcp_done(struct sock *sk);
1087
1088static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1089{
1090 rx_opt->dsack = 0;
1091 rx_opt->num_sacks = 0;
1092}
1093
1094/* Determine a window scaling and initial window to offer. */
1095extern void tcp_select_initial_window(int __space, __u32 mss,
1096 __u32 *rcv_wnd, __u32 *window_clamp,
1097 int wscale_ok, __u8 *rcv_wscale,
1098 __u32 init_rcv_wnd);
1099
1100static inline int tcp_win_from_space(int space)
1101{
1102 return sysctl_tcp_adv_win_scale<=0 ?
1103 (space>>(-sysctl_tcp_adv_win_scale)) :
1104 space - (space>>sysctl_tcp_adv_win_scale);
1105}
1106
1107/* Note: caller must be prepared to deal with negative returns */
1108static inline int tcp_space(const struct sock *sk)
1109{
1110 return tcp_win_from_space(sk->sk_rcvbuf -
1111 atomic_read(&sk->sk_rmem_alloc));
1112}
1113
1114static inline int tcp_full_space(const struct sock *sk)
1115{
1116 return tcp_win_from_space(sk->sk_rcvbuf);
1117}
1118
1119static inline void tcp_openreq_init(struct request_sock *req,
1120 struct tcp_options_received *rx_opt,
1121 struct sk_buff *skb)
1122{
1123 struct inet_request_sock *ireq = inet_rsk(req);
1124
1125 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1126 req->cookie_ts = 0;
1127 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1128 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
1129 tcp_rsk(req)->snt_synack = 0;
1130 req->mss = rx_opt->mss_clamp;
1131 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1132 ireq->tstamp_ok = rx_opt->tstamp_ok;
1133 ireq->sack_ok = rx_opt->sack_ok;
1134 ireq->snd_wscale = rx_opt->snd_wscale;
1135 ireq->wscale_ok = rx_opt->wscale_ok;
1136 ireq->acked = 0;
1137 ireq->ecn_ok = 0;
1138 ireq->rmt_port = tcp_hdr(skb)->source;
1139 ireq->loc_port = tcp_hdr(skb)->dest;
1140}
1141
1142/* Compute time elapsed between SYNACK and the ACK completing 3WHS */
1143static inline void tcp_synack_rtt_meas(struct sock *sk,
1144 struct request_sock *req)
1145{
1146 if (tcp_rsk(req)->snt_synack)
1147 tcp_valid_rtt_meas(sk,
1148 tcp_time_stamp - tcp_rsk(req)->snt_synack);
1149}
1150
1151extern void tcp_enter_memory_pressure(struct sock *sk);
1152
1153static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1154{
1155 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1156}
1157
1158static inline int keepalive_time_when(const struct tcp_sock *tp)
1159{
1160 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1161}
1162
1163static inline int keepalive_probes(const struct tcp_sock *tp)
1164{
1165 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1166}
1167
1168static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1169{
1170 const struct inet_connection_sock *icsk = &tp->inet_conn;
1171
1172 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1173 tcp_time_stamp - tp->rcv_tstamp);
1174}
1175
1176static inline int tcp_fin_time(const struct sock *sk)
1177{
1178 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1179 const int rto = inet_csk(sk)->icsk_rto;
1180
1181 if (fin_timeout < (rto << 2) - (rto >> 1))
1182 fin_timeout = (rto << 2) - (rto >> 1);
1183
1184 return fin_timeout;
1185}
1186
1187static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1188 int paws_win)
1189{
1190 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1191 return true;
1192 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1193 return true;
1194 /*
1195 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1196 * then following tcp messages have valid values. Ignore 0 value,
1197 * or else 'negative' tsval might forbid us to accept their packets.
1198 */
1199 if (!rx_opt->ts_recent)
1200 return true;
1201 return false;
1202}
1203
1204static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1205 int rst)
1206{
1207 if (tcp_paws_check(rx_opt, 0))
1208 return false;
1209
1210 /* RST segments are not recommended to carry timestamp,
1211 and, if they do, it is recommended to ignore PAWS because
1212 "their cleanup function should take precedence over timestamps."
1213 Certainly, it is mistake. It is necessary to understand the reasons
1214 of this constraint to relax it: if peer reboots, clock may go
1215 out-of-sync and half-open connections will not be reset.
1216 Actually, the problem would be not existing if all
1217 the implementations followed draft about maintaining clock
1218 via reboots. Linux-2.2 DOES NOT!
1219
1220 However, we can relax time bounds for RST segments to MSL.
1221 */
1222 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1223 return false;
1224 return true;
1225}
1226
1227static inline void tcp_mib_init(struct net *net)
1228{
1229 /* See RFC 2012 */
1230 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1231 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1232 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1233 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1234}
1235
1236/* from STCP */
1237static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1238{
1239 tp->lost_skb_hint = NULL;
1240 tp->scoreboard_skb_hint = NULL;
1241}
1242
1243static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1244{
1245 tcp_clear_retrans_hints_partial(tp);
1246 tp->retransmit_skb_hint = NULL;
1247}
1248
1249/* MD5 Signature */
1250struct crypto_hash;
1251
1252union tcp_md5_addr {
1253 struct in_addr a4;
1254#if IS_ENABLED(CONFIG_IPV6)
1255 struct in6_addr a6;
1256#endif
1257};
1258
1259/* - key database */
1260struct tcp_md5sig_key {
1261 struct hlist_node node;
1262 u8 keylen;
1263 u8 family; /* AF_INET or AF_INET6 */
1264 union tcp_md5_addr addr;
1265 u8 key[TCP_MD5SIG_MAXKEYLEN];
1266 struct rcu_head rcu;
1267};
1268
1269/* - sock block */
1270struct tcp_md5sig_info {
1271 struct hlist_head head;
1272 struct rcu_head rcu;
1273};
1274
1275/* - pseudo header */
1276struct tcp4_pseudohdr {
1277 __be32 saddr;
1278 __be32 daddr;
1279 __u8 pad;
1280 __u8 protocol;
1281 __be16 len;
1282};
1283
1284struct tcp6_pseudohdr {
1285 struct in6_addr saddr;
1286 struct in6_addr daddr;
1287 __be32 len;
1288 __be32 protocol; /* including padding */
1289};
1290
1291union tcp_md5sum_block {
1292 struct tcp4_pseudohdr ip4;
1293#if IS_ENABLED(CONFIG_IPV6)
1294 struct tcp6_pseudohdr ip6;
1295#endif
1296};
1297
1298/* - pool: digest algorithm, hash description and scratch buffer */
1299struct tcp_md5sig_pool {
1300 struct hash_desc md5_desc;
1301 union tcp_md5sum_block md5_blk;
1302};
1303
1304/* - functions */
1305extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1306 const struct sock *sk,
1307 const struct request_sock *req,
1308 const struct sk_buff *skb);
1309extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1310 int family, const u8 *newkey,
1311 u8 newkeylen, gfp_t gfp);
1312extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1313 int family);
1314extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1315 struct sock *addr_sk);
1316
1317#ifdef CONFIG_TCP_MD5SIG
1318extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1319 const union tcp_md5_addr *addr, int family);
1320#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1321#else
1322static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1323 const union tcp_md5_addr *addr,
1324 int family)
1325{
1326 return NULL;
1327}
1328#define tcp_twsk_md5_key(twsk) NULL
1329#endif
1330
1331extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1332extern void tcp_free_md5sig_pool(void);
1333
1334extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1335extern void tcp_put_md5sig_pool(void);
1336
1337extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1338extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1339 unsigned int header_len);
1340extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1341 const struct tcp_md5sig_key *key);
1342
1343/* From tcp_fastopen.c */
1344extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1345 struct tcp_fastopen_cookie *cookie,
1346 int *syn_loss, unsigned long *last_syn_loss);
1347extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1348 struct tcp_fastopen_cookie *cookie,
1349 bool syn_lost);
1350struct tcp_fastopen_request {
1351 /* Fast Open cookie. Size 0 means a cookie request */
1352 struct tcp_fastopen_cookie cookie;
1353 struct msghdr *data; /* data in MSG_FASTOPEN */
1354 u16 copied; /* queued in tcp_connect() */
1355};
1356void tcp_free_fastopen_req(struct tcp_sock *tp);
1357
1358extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1359int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1360void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc);
1361
1362#define TCP_FASTOPEN_KEY_LENGTH 16
1363
1364/* Fastopen key context */
1365struct tcp_fastopen_context {
1366 struct crypto_cipher __rcu *tfm;
1367 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1368 struct rcu_head rcu;
1369};
1370
1371/* write queue abstraction */
1372static inline void tcp_write_queue_purge(struct sock *sk)
1373{
1374 struct sk_buff *skb;
1375
1376 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1377 sk_wmem_free_skb(sk, skb);
1378 sk_mem_reclaim(sk);
1379 tcp_clear_all_retrans_hints(tcp_sk(sk));
1380}
1381
1382static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1383{
1384 return skb_peek(&sk->sk_write_queue);
1385}
1386
1387static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1388{
1389 return skb_peek_tail(&sk->sk_write_queue);
1390}
1391
1392static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1393 const struct sk_buff *skb)
1394{
1395 return skb_queue_next(&sk->sk_write_queue, skb);
1396}
1397
1398static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1399 const struct sk_buff *skb)
1400{
1401 return skb_queue_prev(&sk->sk_write_queue, skb);
1402}
1403
1404#define tcp_for_write_queue(skb, sk) \
1405 skb_queue_walk(&(sk)->sk_write_queue, skb)
1406
1407#define tcp_for_write_queue_from(skb, sk) \
1408 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1409
1410#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1411 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1412
1413static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1414{
1415 return sk->sk_send_head;
1416}
1417
1418static inline bool tcp_skb_is_last(const struct sock *sk,
1419 const struct sk_buff *skb)
1420{
1421 return skb_queue_is_last(&sk->sk_write_queue, skb);
1422}
1423
1424static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1425{
1426 if (tcp_skb_is_last(sk, skb))
1427 sk->sk_send_head = NULL;
1428 else
1429 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1430}
1431
1432static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1433{
1434 if (sk->sk_send_head == skb_unlinked)
1435 sk->sk_send_head = NULL;
1436}
1437
1438static inline void tcp_init_send_head(struct sock *sk)
1439{
1440 sk->sk_send_head = NULL;
1441}
1442
1443static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1444{
1445 __skb_queue_tail(&sk->sk_write_queue, skb);
1446}
1447
1448static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1449{
1450 __tcp_add_write_queue_tail(sk, skb);
1451
1452 /* Queue it, remembering where we must start sending. */
1453 if (sk->sk_send_head == NULL) {
1454 sk->sk_send_head = skb;
1455
1456 if (tcp_sk(sk)->highest_sack == NULL)
1457 tcp_sk(sk)->highest_sack = skb;
1458 }
1459}
1460
1461static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1462{
1463 __skb_queue_head(&sk->sk_write_queue, skb);
1464}
1465
1466/* Insert buff after skb on the write queue of sk. */
1467static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1468 struct sk_buff *buff,
1469 struct sock *sk)
1470{
1471 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1472}
1473
1474/* Insert new before skb on the write queue of sk. */
1475static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1476 struct sk_buff *skb,
1477 struct sock *sk)
1478{
1479 __skb_queue_before(&sk->sk_write_queue, skb, new);
1480
1481 if (sk->sk_send_head == skb)
1482 sk->sk_send_head = new;
1483}
1484
1485static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1486{
1487 __skb_unlink(skb, &sk->sk_write_queue);
1488}
1489
1490static inline bool tcp_write_queue_empty(struct sock *sk)
1491{
1492 return skb_queue_empty(&sk->sk_write_queue);
1493}
1494
1495static inline void tcp_push_pending_frames(struct sock *sk)
1496{
1497 if (tcp_send_head(sk)) {
1498 struct tcp_sock *tp = tcp_sk(sk);
1499
1500 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1501 }
1502}
1503
1504/* Start sequence of the skb just after the highest skb with SACKed
1505 * bit, valid only if sacked_out > 0 or when the caller has ensured
1506 * validity by itself.
1507 */
1508static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1509{
1510 if (!tp->sacked_out)
1511 return tp->snd_una;
1512
1513 if (tp->highest_sack == NULL)
1514 return tp->snd_nxt;
1515
1516 return TCP_SKB_CB(tp->highest_sack)->seq;
1517}
1518
1519static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1520{
1521 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1522 tcp_write_queue_next(sk, skb);
1523}
1524
1525static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1526{
1527 return tcp_sk(sk)->highest_sack;
1528}
1529
1530static inline void tcp_highest_sack_reset(struct sock *sk)
1531{
1532 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1533}
1534
1535/* Called when old skb is about to be deleted (to be combined with new skb) */
1536static inline void tcp_highest_sack_combine(struct sock *sk,
1537 struct sk_buff *old,
1538 struct sk_buff *new)
1539{
1540 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1541 tcp_sk(sk)->highest_sack = new;
1542}
1543
1544/* Determines whether this is a thin stream (which may suffer from
1545 * increased latency). Used to trigger latency-reducing mechanisms.
1546 */
1547static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1548{
1549 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1550}
1551
1552/* /proc */
1553enum tcp_seq_states {
1554 TCP_SEQ_STATE_LISTENING,
1555 TCP_SEQ_STATE_OPENREQ,
1556 TCP_SEQ_STATE_ESTABLISHED,
1557 TCP_SEQ_STATE_TIME_WAIT,
1558};
1559
1560int tcp_seq_open(struct inode *inode, struct file *file);
1561
1562struct tcp_seq_afinfo {
1563 char *name;
1564 sa_family_t family;
1565 const struct file_operations *seq_fops;
1566 struct seq_operations seq_ops;
1567};
1568
1569struct tcp_iter_state {
1570 struct seq_net_private p;
1571 sa_family_t family;
1572 enum tcp_seq_states state;
1573 struct sock *syn_wait_sk;
1574 int bucket, offset, sbucket, num;
1575 kuid_t uid;
1576 loff_t last_pos;
1577};
1578
1579extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1580extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1581
1582extern struct request_sock_ops tcp_request_sock_ops;
1583extern struct request_sock_ops tcp6_request_sock_ops;
1584
1585extern void tcp_v4_destroy_sock(struct sock *sk);
1586
1587extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1588extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1589 netdev_features_t features);
1590extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1591 struct sk_buff *skb);
1592extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1593 struct sk_buff *skb);
1594extern int tcp_gro_complete(struct sk_buff *skb);
1595extern int tcp4_gro_complete(struct sk_buff *skb);
1596
1597#ifdef CONFIG_PROC_FS
1598extern int tcp4_proc_init(void);
1599extern void tcp4_proc_exit(void);
1600#endif
1601
1602/* TCP af-specific functions */
1603struct tcp_sock_af_ops {
1604#ifdef CONFIG_TCP_MD5SIG
1605 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1606 struct sock *addr_sk);
1607 int (*calc_md5_hash) (char *location,
1608 struct tcp_md5sig_key *md5,
1609 const struct sock *sk,
1610 const struct request_sock *req,
1611 const struct sk_buff *skb);
1612 int (*md5_parse) (struct sock *sk,
1613 char __user *optval,
1614 int optlen);
1615#endif
1616};
1617
1618struct tcp_request_sock_ops {
1619#ifdef CONFIG_TCP_MD5SIG
1620 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1621 struct request_sock *req);
1622 int (*calc_md5_hash) (char *location,
1623 struct tcp_md5sig_key *md5,
1624 const struct sock *sk,
1625 const struct request_sock *req,
1626 const struct sk_buff *skb);
1627#endif
1628};
1629
1630/* Using SHA1 for now, define some constants.
1631 */
1632#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1633#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1634#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1635
1636extern int tcp_cookie_generator(u32 *bakery);
1637
1638/**
1639 * struct tcp_cookie_values - each socket needs extra space for the
1640 * cookies, together with (optional) space for any SYN data.
1641 *
1642 * A tcp_sock contains a pointer to the current value, and this is
1643 * cloned to the tcp_timewait_sock.
1644 *
1645 * @cookie_pair: variable data from the option exchange.
1646 *
1647 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1648 * indicates default (sysctl_tcp_cookie_size).
1649 * After cookie sent, remembers size of cookie.
1650 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1651 *
1652 * @s_data_desired: user specified tcpct_s_data_desired. When the
1653 * constant payload is specified (@s_data_constant),
1654 * holds its length instead.
1655 * Range 0 to TCP_MSS_DESIRED.
1656 *
1657 * @s_data_payload: constant data that is to be included in the
1658 * payload of SYN or SYNACK segments when the
1659 * cookie option is present.
1660 */
1661struct tcp_cookie_values {
1662 struct kref kref;
1663 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1664 u8 cookie_pair_size;
1665 u8 cookie_desired;
1666 u16 s_data_desired:11,
1667 s_data_constant:1,
1668 s_data_in:1,
1669 s_data_out:1,
1670 s_data_unused:2;
1671 u8 s_data_payload[0];
1672};
1673
1674static inline void tcp_cookie_values_release(struct kref *kref)
1675{
1676 kfree(container_of(kref, struct tcp_cookie_values, kref));
1677}
1678
1679/* The length of constant payload data. Note that s_data_desired is
1680 * overloaded, depending on s_data_constant: either the length of constant
1681 * data (returned here) or the limit on variable data.
1682 */
1683static inline int tcp_s_data_size(const struct tcp_sock *tp)
1684{
1685 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1686 ? tp->cookie_values->s_data_desired
1687 : 0;
1688}
1689
1690/**
1691 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1692 *
1693 * As tcp_request_sock has already been extended in other places, the
1694 * only remaining method is to pass stack values along as function
1695 * parameters. These parameters are not needed after sending SYNACK.
1696 *
1697 * @cookie_bakery: cryptographic secret and message workspace.
1698 *
1699 * @cookie_plus: bytes in authenticator/cookie option, copied from
1700 * struct tcp_options_received (above).
1701 */
1702struct tcp_extend_values {
1703 struct request_values rv;
1704 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1705 u8 cookie_plus:6,
1706 cookie_out_never:1,
1707 cookie_in_always:1;
1708};
1709
1710static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1711{
1712 return (struct tcp_extend_values *)rvp;
1713}
1714
1715extern void tcp_v4_init(void);
1716extern void tcp_init(void);
1717
1718#endif /* _TCP_H */