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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 TCP_DEBUG 1
22#define FASTRETRANS_DEBUG 1
23
24#include <linux/list.h>
25#include <linux/tcp.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
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52extern void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER (128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56
57/*
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
60 */
61#define MAX_TCP_WINDOW 32767U
62
63/* Offer an initial receive window of 10 mss. */
64#define TCP_DEFAULT_INIT_RCVWND 10
65
66/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
67#define TCP_MIN_MSS 88U
68
69/* The least MTU to use for probing */
70#define TCP_BASE_MSS 512
71
72/* After receiving this amount of duplicate ACKs fast retransmit starts. */
73#define TCP_FASTRETRANS_THRESH 3
74
75/* Maximal reordering. */
76#define TCP_MAX_REORDERING 127
77
78/* Maximal number of ACKs sent quickly to accelerate slow-start. */
79#define TCP_MAX_QUICKACKS 16U
80
81/* urg_data states */
82#define TCP_URG_VALID 0x0100
83#define TCP_URG_NOTYET 0x0200
84#define TCP_URG_READ 0x0400
85
86#define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
91 */
92
93#define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
98 */
99
100#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
101 * connection: ~180sec is RFC minimum */
102
103#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
104 * connection: ~180sec is RFC minimum */
105
106#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
107 * state, about 60 seconds */
108#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
109 /* BSD style FIN_WAIT2 deadlock breaker.
110 * It used to be 3min, new value is 60sec,
111 * to combine FIN-WAIT-2 timeout with
112 * TIME-WAIT timer.
113 */
114
115#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
116#if HZ >= 100
117#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
118#define TCP_ATO_MIN ((unsigned)(HZ/25))
119#else
120#define TCP_DELACK_MIN 4U
121#define TCP_ATO_MIN 4U
122#endif
123#define TCP_RTO_MAX ((unsigned)(120*HZ))
124#define TCP_RTO_MIN ((unsigned)(HZ/5))
125#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC2988bis initial RTO value */
126#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
127 * used as a fallback RTO for the
128 * initial data transmission if no
129 * valid RTT sample has been acquired,
130 * most likely due to retrans in 3WHS.
131 */
132
133#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
134 * for local resources.
135 */
136
137#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
138#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
139#define TCP_KEEPALIVE_INTVL (75*HZ)
140
141#define MAX_TCP_KEEPIDLE 32767
142#define MAX_TCP_KEEPINTVL 32767
143#define MAX_TCP_KEEPCNT 127
144#define MAX_TCP_SYNCNT 127
145
146#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
147
148#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
149#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
150 * after this time. It should be equal
151 * (or greater than) TCP_TIMEWAIT_LEN
152 * to provide reliability equal to one
153 * provided by timewait state.
154 */
155#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
156 * timestamps. It must be less than
157 * minimal timewait lifetime.
158 */
159/*
160 * TCP option
161 */
162
163#define TCPOPT_NOP 1 /* Padding */
164#define TCPOPT_EOL 0 /* End of options */
165#define TCPOPT_MSS 2 /* Segment size negotiating */
166#define TCPOPT_WINDOW 3 /* Window scaling */
167#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
168#define TCPOPT_SACK 5 /* SACK Block */
169#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
170#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
171#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
172
173/*
174 * TCP option lengths
175 */
176
177#define TCPOLEN_MSS 4
178#define TCPOLEN_WINDOW 3
179#define TCPOLEN_SACK_PERM 2
180#define TCPOLEN_TIMESTAMP 10
181#define TCPOLEN_MD5SIG 18
182#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
183#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
184#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
185#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
186
187/* But this is what stacks really send out. */
188#define TCPOLEN_TSTAMP_ALIGNED 12
189#define TCPOLEN_WSCALE_ALIGNED 4
190#define TCPOLEN_SACKPERM_ALIGNED 4
191#define TCPOLEN_SACK_BASE 2
192#define TCPOLEN_SACK_BASE_ALIGNED 4
193#define TCPOLEN_SACK_PERBLOCK 8
194#define TCPOLEN_MD5SIG_ALIGNED 20
195#define TCPOLEN_MSS_ALIGNED 4
196
197/* Flags in tp->nonagle */
198#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
199#define TCP_NAGLE_CORK 2 /* Socket is corked */
200#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
201
202/* TCP thin-stream limits */
203#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
204
205/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
206#define TCP_INIT_CWND 10
207
208extern struct inet_timewait_death_row tcp_death_row;
209
210/* sysctl variables for tcp */
211extern int sysctl_tcp_timestamps;
212extern int sysctl_tcp_window_scaling;
213extern int sysctl_tcp_sack;
214extern int sysctl_tcp_fin_timeout;
215extern int sysctl_tcp_keepalive_time;
216extern int sysctl_tcp_keepalive_probes;
217extern int sysctl_tcp_keepalive_intvl;
218extern int sysctl_tcp_syn_retries;
219extern int sysctl_tcp_synack_retries;
220extern int sysctl_tcp_retries1;
221extern int sysctl_tcp_retries2;
222extern int sysctl_tcp_orphan_retries;
223extern int sysctl_tcp_syncookies;
224extern int sysctl_tcp_retrans_collapse;
225extern int sysctl_tcp_stdurg;
226extern int sysctl_tcp_rfc1337;
227extern int sysctl_tcp_abort_on_overflow;
228extern int sysctl_tcp_max_orphans;
229extern int sysctl_tcp_fack;
230extern int sysctl_tcp_reordering;
231extern int sysctl_tcp_ecn;
232extern int sysctl_tcp_dsack;
233extern long sysctl_tcp_mem[3];
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;
255
256extern atomic_long_t tcp_memory_allocated;
257extern struct percpu_counter tcp_sockets_allocated;
258extern int tcp_memory_pressure;
259
260/*
261 * The next routines deal with comparing 32 bit unsigned ints
262 * and worry about wraparound (automatic with unsigned arithmetic).
263 */
264
265static inline int before(__u32 seq1, __u32 seq2)
266{
267 return (__s32)(seq1-seq2) < 0;
268}
269#define after(seq2, seq1) before(seq1, seq2)
270
271/* is s2<=s1<=s3 ? */
272static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
273{
274 return seq3 - seq2 >= seq1 - seq2;
275}
276
277static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
278{
279 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
280 int orphans = percpu_counter_read_positive(ocp);
281
282 if (orphans << shift > sysctl_tcp_max_orphans) {
283 orphans = percpu_counter_sum_positive(ocp);
284 if (orphans << shift > sysctl_tcp_max_orphans)
285 return true;
286 }
287
288 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
289 atomic_long_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])
290 return true;
291 return false;
292}
293
294/* syncookies: remember time of last synqueue overflow */
295static inline void tcp_synq_overflow(struct sock *sk)
296{
297 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
298}
299
300/* syncookies: no recent synqueue overflow on this listening socket? */
301static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
302{
303 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
304 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
305}
306
307extern struct proto tcp_prot;
308
309#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
311#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
312#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
313#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
314
315extern void tcp_v4_err(struct sk_buff *skb, u32);
316
317extern void tcp_shutdown (struct sock *sk, int how);
318
319extern int tcp_v4_rcv(struct sk_buff *skb);
320
321extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
322extern void *tcp_v4_tw_get_peer(struct sock *sk);
323extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
324extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
325 size_t size);
326extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
327 size_t size, int flags);
328extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
329extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
330 struct tcphdr *th, unsigned len);
331extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
332 struct tcphdr *th, unsigned len);
333extern void tcp_rcv_space_adjust(struct sock *sk);
334extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
335extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
336extern void tcp_twsk_destructor(struct sock *sk);
337extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
338 struct pipe_inode_info *pipe, size_t len,
339 unsigned int flags);
340
341static inline void tcp_dec_quickack_mode(struct sock *sk,
342 const unsigned int pkts)
343{
344 struct inet_connection_sock *icsk = inet_csk(sk);
345
346 if (icsk->icsk_ack.quick) {
347 if (pkts >= icsk->icsk_ack.quick) {
348 icsk->icsk_ack.quick = 0;
349 /* Leaving quickack mode we deflate ATO. */
350 icsk->icsk_ack.ato = TCP_ATO_MIN;
351 } else
352 icsk->icsk_ack.quick -= pkts;
353 }
354}
355
356#define TCP_ECN_OK 1
357#define TCP_ECN_QUEUE_CWR 2
358#define TCP_ECN_DEMAND_CWR 4
359
360static __inline__ void
361TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
362{
363 if (sysctl_tcp_ecn && th->ece && th->cwr)
364 inet_rsk(req)->ecn_ok = 1;
365}
366
367enum tcp_tw_status {
368 TCP_TW_SUCCESS = 0,
369 TCP_TW_RST = 1,
370 TCP_TW_ACK = 2,
371 TCP_TW_SYN = 3
372};
373
374
375extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
376 struct sk_buff *skb,
377 const struct tcphdr *th);
378extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
379 struct request_sock *req,
380 struct request_sock **prev);
381extern int tcp_child_process(struct sock *parent, struct sock *child,
382 struct sk_buff *skb);
383extern int tcp_use_frto(struct sock *sk);
384extern void tcp_enter_frto(struct sock *sk);
385extern void tcp_enter_loss(struct sock *sk, int how);
386extern void tcp_clear_retrans(struct tcp_sock *tp);
387extern void tcp_update_metrics(struct sock *sk);
388extern void tcp_close(struct sock *sk, long timeout);
389extern unsigned int tcp_poll(struct file * file, struct socket *sock,
390 struct poll_table_struct *wait);
391extern int tcp_getsockopt(struct sock *sk, int level, int optname,
392 char __user *optval, int __user *optlen);
393extern int tcp_setsockopt(struct sock *sk, int level, int optname,
394 char __user *optval, unsigned int optlen);
395extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399extern void tcp_set_keepalive(struct sock *sk, int val);
400extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
401extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
402 size_t len, int nonblock, int flags, int *addr_len);
403extern void tcp_parse_options(struct sk_buff *skb,
404 struct tcp_options_received *opt_rx, u8 **hvpp,
405 int estab);
406extern u8 *tcp_parse_md5sig_option(struct tcphdr *th);
407
408/*
409 * TCP v4 functions exported for the inet6 API
410 */
411
412extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
413extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
414extern struct sock * tcp_create_openreq_child(struct sock *sk,
415 struct request_sock *req,
416 struct sk_buff *skb);
417extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
418 struct request_sock *req,
419 struct dst_entry *dst);
420extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
421extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
422 int addr_len);
423extern int tcp_connect(struct sock *sk);
424extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
425 struct request_sock *req,
426 struct request_values *rvp);
427extern int tcp_disconnect(struct sock *sk, int flags);
428
429
430/* From syncookies.c */
431extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
432extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
433 struct ip_options *opt);
434#ifdef CONFIG_SYN_COOKIES
435extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
436 __u16 *mss);
437#else
438static inline __u32 cookie_v4_init_sequence(struct sock *sk,
439 struct sk_buff *skb,
440 __u16 *mss)
441{
442 return 0;
443}
444#endif
445
446extern __u32 cookie_init_timestamp(struct request_sock *req);
447extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
448
449/* From net/ipv6/syncookies.c */
450extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
451#ifdef CONFIG_SYN_COOKIES
452extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb,
453 __u16 *mss);
454#else
455static inline __u32 cookie_v6_init_sequence(struct sock *sk,
456 struct sk_buff *skb,
457 __u16 *mss)
458{
459 return 0;
460}
461#endif
462/* tcp_output.c */
463
464extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
465 int nonagle);
466extern int tcp_may_send_now(struct sock *sk);
467extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
468extern void tcp_retransmit_timer(struct sock *sk);
469extern void tcp_xmit_retransmit_queue(struct sock *);
470extern void tcp_simple_retransmit(struct sock *);
471extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
472extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
473
474extern void tcp_send_probe0(struct sock *);
475extern void tcp_send_partial(struct sock *);
476extern int tcp_write_wakeup(struct sock *);
477extern void tcp_send_fin(struct sock *sk);
478extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
479extern int tcp_send_synack(struct sock *);
480extern int tcp_syn_flood_action(struct sock *sk,
481 const struct sk_buff *skb,
482 const char *proto);
483extern void tcp_push_one(struct sock *, unsigned int mss_now);
484extern void tcp_send_ack(struct sock *sk);
485extern void tcp_send_delayed_ack(struct sock *sk);
486
487/* tcp_input.c */
488extern void tcp_cwnd_application_limited(struct sock *sk);
489
490/* tcp_timer.c */
491extern void tcp_init_xmit_timers(struct sock *);
492static inline void tcp_clear_xmit_timers(struct sock *sk)
493{
494 inet_csk_clear_xmit_timers(sk);
495}
496
497extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
498extern unsigned int tcp_current_mss(struct sock *sk);
499
500/* Bound MSS / TSO packet size with the half of the window */
501static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
502{
503 int cutoff;
504
505 /* When peer uses tiny windows, there is no use in packetizing
506 * to sub-MSS pieces for the sake of SWS or making sure there
507 * are enough packets in the pipe for fast recovery.
508 *
509 * On the other hand, for extremely large MSS devices, handling
510 * smaller than MSS windows in this way does make sense.
511 */
512 if (tp->max_window >= 512)
513 cutoff = (tp->max_window >> 1);
514 else
515 cutoff = tp->max_window;
516
517 if (cutoff && pktsize > cutoff)
518 return max_t(int, cutoff, 68U - tp->tcp_header_len);
519 else
520 return pktsize;
521}
522
523/* tcp.c */
524extern void tcp_get_info(struct sock *, struct tcp_info *);
525
526/* Read 'sendfile()'-style from a TCP socket */
527typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
528 unsigned int, size_t);
529extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
530 sk_read_actor_t recv_actor);
531
532extern void tcp_initialize_rcv_mss(struct sock *sk);
533
534extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
535extern int tcp_mss_to_mtu(struct sock *sk, int mss);
536extern void tcp_mtup_init(struct sock *sk);
537extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
538
539static inline void tcp_bound_rto(const struct sock *sk)
540{
541 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
542 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
543}
544
545static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
546{
547 return (tp->srtt >> 3) + tp->rttvar;
548}
549
550static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
551{
552 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
553 ntohl(TCP_FLAG_ACK) |
554 snd_wnd);
555}
556
557static inline void tcp_fast_path_on(struct tcp_sock *tp)
558{
559 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
560}
561
562static inline void tcp_fast_path_check(struct sock *sk)
563{
564 struct tcp_sock *tp = tcp_sk(sk);
565
566 if (skb_queue_empty(&tp->out_of_order_queue) &&
567 tp->rcv_wnd &&
568 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
569 !tp->urg_data)
570 tcp_fast_path_on(tp);
571}
572
573/* Compute the actual rto_min value */
574static inline u32 tcp_rto_min(struct sock *sk)
575{
576 struct dst_entry *dst = __sk_dst_get(sk);
577 u32 rto_min = TCP_RTO_MIN;
578
579 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
580 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
581 return rto_min;
582}
583
584/* Compute the actual receive window we are currently advertising.
585 * Rcv_nxt can be after the window if our peer push more data
586 * than the offered window.
587 */
588static inline u32 tcp_receive_window(const struct tcp_sock *tp)
589{
590 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
591
592 if (win < 0)
593 win = 0;
594 return (u32) win;
595}
596
597/* Choose a new window, without checks for shrinking, and without
598 * scaling applied to the result. The caller does these things
599 * if necessary. This is a "raw" window selection.
600 */
601extern u32 __tcp_select_window(struct sock *sk);
602
603/* TCP timestamps are only 32-bits, this causes a slight
604 * complication on 64-bit systems since we store a snapshot
605 * of jiffies in the buffer control blocks below. We decided
606 * to use only the low 32-bits of jiffies and hide the ugly
607 * casts with the following macro.
608 */
609#define tcp_time_stamp ((__u32)(jiffies))
610
611#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
612
613#define TCPHDR_FIN 0x01
614#define TCPHDR_SYN 0x02
615#define TCPHDR_RST 0x04
616#define TCPHDR_PSH 0x08
617#define TCPHDR_ACK 0x10
618#define TCPHDR_URG 0x20
619#define TCPHDR_ECE 0x40
620#define TCPHDR_CWR 0x80
621
622/* This is what the send packet queuing engine uses to pass
623 * TCP per-packet control information to the transmission code.
624 * We also store the host-order sequence numbers in here too.
625 * This is 44 bytes if IPV6 is enabled.
626 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
627 */
628struct tcp_skb_cb {
629 union {
630 struct inet_skb_parm h4;
631#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
632 struct inet6_skb_parm h6;
633#endif
634 } header; /* For incoming frames */
635 __u32 seq; /* Starting sequence number */
636 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
637 __u32 when; /* used to compute rtt's */
638 __u8 flags; /* TCP header flags. */
639 __u8 sacked; /* State flags for SACK/FACK. */
640#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
641#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
642#define TCPCB_LOST 0x04 /* SKB is lost */
643#define TCPCB_TAGBITS 0x07 /* All tag bits */
644
645#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
646#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
647
648 __u32 ack_seq; /* Sequence number ACK'd */
649};
650
651#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
652
653/* Due to TSO, an SKB can be composed of multiple actual
654 * packets. To keep these tracked properly, we use this.
655 */
656static inline int tcp_skb_pcount(const struct sk_buff *skb)
657{
658 return skb_shinfo(skb)->gso_segs;
659}
660
661/* This is valid iff tcp_skb_pcount() > 1. */
662static inline int tcp_skb_mss(const struct sk_buff *skb)
663{
664 return skb_shinfo(skb)->gso_size;
665}
666
667/* Events passed to congestion control interface */
668enum tcp_ca_event {
669 CA_EVENT_TX_START, /* first transmit when no packets in flight */
670 CA_EVENT_CWND_RESTART, /* congestion window restart */
671 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
672 CA_EVENT_FRTO, /* fast recovery timeout */
673 CA_EVENT_LOSS, /* loss timeout */
674 CA_EVENT_FAST_ACK, /* in sequence ack */
675 CA_EVENT_SLOW_ACK, /* other ack */
676};
677
678/*
679 * Interface for adding new TCP congestion control handlers
680 */
681#define TCP_CA_NAME_MAX 16
682#define TCP_CA_MAX 128
683#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
684
685#define TCP_CONG_NON_RESTRICTED 0x1
686#define TCP_CONG_RTT_STAMP 0x2
687
688struct tcp_congestion_ops {
689 struct list_head list;
690 unsigned long flags;
691
692 /* initialize private data (optional) */
693 void (*init)(struct sock *sk);
694 /* cleanup private data (optional) */
695 void (*release)(struct sock *sk);
696
697 /* return slow start threshold (required) */
698 u32 (*ssthresh)(struct sock *sk);
699 /* lower bound for congestion window (optional) */
700 u32 (*min_cwnd)(const struct sock *sk);
701 /* do new cwnd calculation (required) */
702 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
703 /* call before changing ca_state (optional) */
704 void (*set_state)(struct sock *sk, u8 new_state);
705 /* call when cwnd event occurs (optional) */
706 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
707 /* new value of cwnd after loss (optional) */
708 u32 (*undo_cwnd)(struct sock *sk);
709 /* hook for packet ack accounting (optional) */
710 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
711 /* get info for inet_diag (optional) */
712 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
713
714 char name[TCP_CA_NAME_MAX];
715 struct module *owner;
716};
717
718extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
719extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
720
721extern void tcp_init_congestion_control(struct sock *sk);
722extern void tcp_cleanup_congestion_control(struct sock *sk);
723extern int tcp_set_default_congestion_control(const char *name);
724extern void tcp_get_default_congestion_control(char *name);
725extern void tcp_get_available_congestion_control(char *buf, size_t len);
726extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
727extern int tcp_set_allowed_congestion_control(char *allowed);
728extern int tcp_set_congestion_control(struct sock *sk, const char *name);
729extern void tcp_slow_start(struct tcp_sock *tp);
730extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
731
732extern struct tcp_congestion_ops tcp_init_congestion_ops;
733extern u32 tcp_reno_ssthresh(struct sock *sk);
734extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
735extern u32 tcp_reno_min_cwnd(const struct sock *sk);
736extern struct tcp_congestion_ops tcp_reno;
737
738static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
739{
740 struct inet_connection_sock *icsk = inet_csk(sk);
741
742 if (icsk->icsk_ca_ops->set_state)
743 icsk->icsk_ca_ops->set_state(sk, ca_state);
744 icsk->icsk_ca_state = ca_state;
745}
746
747static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
748{
749 const struct inet_connection_sock *icsk = inet_csk(sk);
750
751 if (icsk->icsk_ca_ops->cwnd_event)
752 icsk->icsk_ca_ops->cwnd_event(sk, event);
753}
754
755/* These functions determine how the current flow behaves in respect of SACK
756 * handling. SACK is negotiated with the peer, and therefore it can vary
757 * between different flows.
758 *
759 * tcp_is_sack - SACK enabled
760 * tcp_is_reno - No SACK
761 * tcp_is_fack - FACK enabled, implies SACK enabled
762 */
763static inline int tcp_is_sack(const struct tcp_sock *tp)
764{
765 return tp->rx_opt.sack_ok;
766}
767
768static inline int tcp_is_reno(const struct tcp_sock *tp)
769{
770 return !tcp_is_sack(tp);
771}
772
773static inline int tcp_is_fack(const struct tcp_sock *tp)
774{
775 return tp->rx_opt.sack_ok & 2;
776}
777
778static inline void tcp_enable_fack(struct tcp_sock *tp)
779{
780 tp->rx_opt.sack_ok |= 2;
781}
782
783static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
784{
785 return tp->sacked_out + tp->lost_out;
786}
787
788/* This determines how many packets are "in the network" to the best
789 * of our knowledge. In many cases it is conservative, but where
790 * detailed information is available from the receiver (via SACK
791 * blocks etc.) we can make more aggressive calculations.
792 *
793 * Use this for decisions involving congestion control, use just
794 * tp->packets_out to determine if the send queue is empty or not.
795 *
796 * Read this equation as:
797 *
798 * "Packets sent once on transmission queue" MINUS
799 * "Packets left network, but not honestly ACKed yet" PLUS
800 * "Packets fast retransmitted"
801 */
802static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
803{
804 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
805}
806
807#define TCP_INFINITE_SSTHRESH 0x7fffffff
808
809static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
810{
811 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
812}
813
814/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
815 * The exception is rate halving phase, when cwnd is decreasing towards
816 * ssthresh.
817 */
818static inline __u32 tcp_current_ssthresh(const struct sock *sk)
819{
820 const struct tcp_sock *tp = tcp_sk(sk);
821 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
822 return tp->snd_ssthresh;
823 else
824 return max(tp->snd_ssthresh,
825 ((tp->snd_cwnd >> 1) +
826 (tp->snd_cwnd >> 2)));
827}
828
829/* Use define here intentionally to get WARN_ON location shown at the caller */
830#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
831
832extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
833extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
834
835/* Slow start with delack produces 3 packets of burst, so that
836 * it is safe "de facto". This will be the default - same as
837 * the default reordering threshold - but if reordering increases,
838 * we must be able to allow cwnd to burst at least this much in order
839 * to not pull it back when holes are filled.
840 */
841static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
842{
843 return tp->reordering;
844}
845
846/* Returns end sequence number of the receiver's advertised window */
847static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
848{
849 return tp->snd_una + tp->snd_wnd;
850}
851extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
852
853static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
854 const struct sk_buff *skb)
855{
856 if (skb->len < mss)
857 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
858}
859
860static inline void tcp_check_probe_timer(struct sock *sk)
861{
862 struct tcp_sock *tp = tcp_sk(sk);
863 const struct inet_connection_sock *icsk = inet_csk(sk);
864
865 if (!tp->packets_out && !icsk->icsk_pending)
866 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
867 icsk->icsk_rto, TCP_RTO_MAX);
868}
869
870static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
871{
872 tp->snd_wl1 = seq;
873}
874
875static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
876{
877 tp->snd_wl1 = seq;
878}
879
880/*
881 * Calculate(/check) TCP checksum
882 */
883static inline __sum16 tcp_v4_check(int len, __be32 saddr,
884 __be32 daddr, __wsum base)
885{
886 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
887}
888
889static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
890{
891 return __skb_checksum_complete(skb);
892}
893
894static inline int tcp_checksum_complete(struct sk_buff *skb)
895{
896 return !skb_csum_unnecessary(skb) &&
897 __tcp_checksum_complete(skb);
898}
899
900/* Prequeue for VJ style copy to user, combined with checksumming. */
901
902static inline void tcp_prequeue_init(struct tcp_sock *tp)
903{
904 tp->ucopy.task = NULL;
905 tp->ucopy.len = 0;
906 tp->ucopy.memory = 0;
907 skb_queue_head_init(&tp->ucopy.prequeue);
908#ifdef CONFIG_NET_DMA
909 tp->ucopy.dma_chan = NULL;
910 tp->ucopy.wakeup = 0;
911 tp->ucopy.pinned_list = NULL;
912 tp->ucopy.dma_cookie = 0;
913#endif
914}
915
916/* Packet is added to VJ-style prequeue for processing in process
917 * context, if a reader task is waiting. Apparently, this exciting
918 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
919 * failed somewhere. Latency? Burstiness? Well, at least now we will
920 * see, why it failed. 8)8) --ANK
921 *
922 * NOTE: is this not too big to inline?
923 */
924static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
925{
926 struct tcp_sock *tp = tcp_sk(sk);
927
928 if (sysctl_tcp_low_latency || !tp->ucopy.task)
929 return 0;
930
931 __skb_queue_tail(&tp->ucopy.prequeue, skb);
932 tp->ucopy.memory += skb->truesize;
933 if (tp->ucopy.memory > sk->sk_rcvbuf) {
934 struct sk_buff *skb1;
935
936 BUG_ON(sock_owned_by_user(sk));
937
938 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
939 sk_backlog_rcv(sk, skb1);
940 NET_INC_STATS_BH(sock_net(sk),
941 LINUX_MIB_TCPPREQUEUEDROPPED);
942 }
943
944 tp->ucopy.memory = 0;
945 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
946 wake_up_interruptible_sync_poll(sk_sleep(sk),
947 POLLIN | POLLRDNORM | POLLRDBAND);
948 if (!inet_csk_ack_scheduled(sk))
949 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
950 (3 * tcp_rto_min(sk)) / 4,
951 TCP_RTO_MAX);
952 }
953 return 1;
954}
955
956
957#undef STATE_TRACE
958
959#ifdef STATE_TRACE
960static const char *statename[]={
961 "Unused","Established","Syn Sent","Syn Recv",
962 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
963 "Close Wait","Last ACK","Listen","Closing"
964};
965#endif
966extern void tcp_set_state(struct sock *sk, int state);
967
968extern void tcp_done(struct sock *sk);
969
970static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
971{
972 rx_opt->dsack = 0;
973 rx_opt->num_sacks = 0;
974}
975
976/* Determine a window scaling and initial window to offer. */
977extern void tcp_select_initial_window(int __space, __u32 mss,
978 __u32 *rcv_wnd, __u32 *window_clamp,
979 int wscale_ok, __u8 *rcv_wscale,
980 __u32 init_rcv_wnd);
981
982static inline int tcp_win_from_space(int space)
983{
984 return sysctl_tcp_adv_win_scale<=0 ?
985 (space>>(-sysctl_tcp_adv_win_scale)) :
986 space - (space>>sysctl_tcp_adv_win_scale);
987}
988
989/* Note: caller must be prepared to deal with negative returns */
990static inline int tcp_space(const struct sock *sk)
991{
992 return tcp_win_from_space(sk->sk_rcvbuf -
993 atomic_read(&sk->sk_rmem_alloc));
994}
995
996static inline int tcp_full_space(const struct sock *sk)
997{
998 return tcp_win_from_space(sk->sk_rcvbuf);
999}
1000
1001static inline void tcp_openreq_init(struct request_sock *req,
1002 struct tcp_options_received *rx_opt,
1003 struct sk_buff *skb)
1004{
1005 struct inet_request_sock *ireq = inet_rsk(req);
1006
1007 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1008 req->cookie_ts = 0;
1009 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1010 req->mss = rx_opt->mss_clamp;
1011 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1012 ireq->tstamp_ok = rx_opt->tstamp_ok;
1013 ireq->sack_ok = rx_opt->sack_ok;
1014 ireq->snd_wscale = rx_opt->snd_wscale;
1015 ireq->wscale_ok = rx_opt->wscale_ok;
1016 ireq->acked = 0;
1017 ireq->ecn_ok = 0;
1018 ireq->rmt_port = tcp_hdr(skb)->source;
1019 ireq->loc_port = tcp_hdr(skb)->dest;
1020}
1021
1022extern void tcp_enter_memory_pressure(struct sock *sk);
1023
1024static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1025{
1026 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1027}
1028
1029static inline int keepalive_time_when(const struct tcp_sock *tp)
1030{
1031 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1032}
1033
1034static inline int keepalive_probes(const struct tcp_sock *tp)
1035{
1036 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1037}
1038
1039static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1040{
1041 const struct inet_connection_sock *icsk = &tp->inet_conn;
1042
1043 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1044 tcp_time_stamp - tp->rcv_tstamp);
1045}
1046
1047static inline int tcp_fin_time(const struct sock *sk)
1048{
1049 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1050 const int rto = inet_csk(sk)->icsk_rto;
1051
1052 if (fin_timeout < (rto << 2) - (rto >> 1))
1053 fin_timeout = (rto << 2) - (rto >> 1);
1054
1055 return fin_timeout;
1056}
1057
1058static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1059 int paws_win)
1060{
1061 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1062 return 1;
1063 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1064 return 1;
1065 /*
1066 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1067 * then following tcp messages have valid values. Ignore 0 value,
1068 * or else 'negative' tsval might forbid us to accept their packets.
1069 */
1070 if (!rx_opt->ts_recent)
1071 return 1;
1072 return 0;
1073}
1074
1075static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1076 int rst)
1077{
1078 if (tcp_paws_check(rx_opt, 0))
1079 return 0;
1080
1081 /* RST segments are not recommended to carry timestamp,
1082 and, if they do, it is recommended to ignore PAWS because
1083 "their cleanup function should take precedence over timestamps."
1084 Certainly, it is mistake. It is necessary to understand the reasons
1085 of this constraint to relax it: if peer reboots, clock may go
1086 out-of-sync and half-open connections will not be reset.
1087 Actually, the problem would be not existing if all
1088 the implementations followed draft about maintaining clock
1089 via reboots. Linux-2.2 DOES NOT!
1090
1091 However, we can relax time bounds for RST segments to MSL.
1092 */
1093 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1094 return 0;
1095 return 1;
1096}
1097
1098static inline void tcp_mib_init(struct net *net)
1099{
1100 /* See RFC 2012 */
1101 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1102 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1103 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1104 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1105}
1106
1107/* from STCP */
1108static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1109{
1110 tp->lost_skb_hint = NULL;
1111 tp->scoreboard_skb_hint = NULL;
1112}
1113
1114static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1115{
1116 tcp_clear_retrans_hints_partial(tp);
1117 tp->retransmit_skb_hint = NULL;
1118}
1119
1120/* MD5 Signature */
1121struct crypto_hash;
1122
1123/* - key database */
1124struct tcp_md5sig_key {
1125 u8 *key;
1126 u8 keylen;
1127};
1128
1129struct tcp4_md5sig_key {
1130 struct tcp_md5sig_key base;
1131 __be32 addr;
1132};
1133
1134struct tcp6_md5sig_key {
1135 struct tcp_md5sig_key base;
1136#if 0
1137 u32 scope_id; /* XXX */
1138#endif
1139 struct in6_addr addr;
1140};
1141
1142/* - sock block */
1143struct tcp_md5sig_info {
1144 struct tcp4_md5sig_key *keys4;
1145#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1146 struct tcp6_md5sig_key *keys6;
1147 u32 entries6;
1148 u32 alloced6;
1149#endif
1150 u32 entries4;
1151 u32 alloced4;
1152};
1153
1154/* - pseudo header */
1155struct tcp4_pseudohdr {
1156 __be32 saddr;
1157 __be32 daddr;
1158 __u8 pad;
1159 __u8 protocol;
1160 __be16 len;
1161};
1162
1163struct tcp6_pseudohdr {
1164 struct in6_addr saddr;
1165 struct in6_addr daddr;
1166 __be32 len;
1167 __be32 protocol; /* including padding */
1168};
1169
1170union tcp_md5sum_block {
1171 struct tcp4_pseudohdr ip4;
1172#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1173 struct tcp6_pseudohdr ip6;
1174#endif
1175};
1176
1177/* - pool: digest algorithm, hash description and scratch buffer */
1178struct tcp_md5sig_pool {
1179 struct hash_desc md5_desc;
1180 union tcp_md5sum_block md5_blk;
1181};
1182
1183/* - functions */
1184extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1185 struct sock *sk, struct request_sock *req,
1186 struct sk_buff *skb);
1187extern struct tcp_md5sig_key * tcp_v4_md5_lookup(struct sock *sk,
1188 struct sock *addr_sk);
1189extern int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, u8 *newkey,
1190 u8 newkeylen);
1191extern int tcp_v4_md5_do_del(struct sock *sk, __be32 addr);
1192
1193#ifdef CONFIG_TCP_MD5SIG
1194#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \
1195 &(struct tcp_md5sig_key) { \
1196 .key = (twsk)->tw_md5_key, \
1197 .keylen = (twsk)->tw_md5_keylen, \
1198 } : NULL)
1199#else
1200#define tcp_twsk_md5_key(twsk) NULL
1201#endif
1202
1203extern struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *);
1204extern void tcp_free_md5sig_pool(void);
1205
1206extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1207extern void tcp_put_md5sig_pool(void);
1208
1209extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *);
1210extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, struct sk_buff *,
1211 unsigned header_len);
1212extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1213 struct tcp_md5sig_key *key);
1214
1215/* write queue abstraction */
1216static inline void tcp_write_queue_purge(struct sock *sk)
1217{
1218 struct sk_buff *skb;
1219
1220 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1221 sk_wmem_free_skb(sk, skb);
1222 sk_mem_reclaim(sk);
1223 tcp_clear_all_retrans_hints(tcp_sk(sk));
1224}
1225
1226static inline struct sk_buff *tcp_write_queue_head(struct sock *sk)
1227{
1228 return skb_peek(&sk->sk_write_queue);
1229}
1230
1231static inline struct sk_buff *tcp_write_queue_tail(struct sock *sk)
1232{
1233 return skb_peek_tail(&sk->sk_write_queue);
1234}
1235
1236static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_buff *skb)
1237{
1238 return skb_queue_next(&sk->sk_write_queue, skb);
1239}
1240
1241static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_buff *skb)
1242{
1243 return skb_queue_prev(&sk->sk_write_queue, skb);
1244}
1245
1246#define tcp_for_write_queue(skb, sk) \
1247 skb_queue_walk(&(sk)->sk_write_queue, skb)
1248
1249#define tcp_for_write_queue_from(skb, sk) \
1250 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1251
1252#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1253 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1254
1255static inline struct sk_buff *tcp_send_head(struct sock *sk)
1256{
1257 return sk->sk_send_head;
1258}
1259
1260static inline bool tcp_skb_is_last(const struct sock *sk,
1261 const struct sk_buff *skb)
1262{
1263 return skb_queue_is_last(&sk->sk_write_queue, skb);
1264}
1265
1266static inline void tcp_advance_send_head(struct sock *sk, struct sk_buff *skb)
1267{
1268 if (tcp_skb_is_last(sk, skb))
1269 sk->sk_send_head = NULL;
1270 else
1271 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1272}
1273
1274static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1275{
1276 if (sk->sk_send_head == skb_unlinked)
1277 sk->sk_send_head = NULL;
1278}
1279
1280static inline void tcp_init_send_head(struct sock *sk)
1281{
1282 sk->sk_send_head = NULL;
1283}
1284
1285static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1286{
1287 __skb_queue_tail(&sk->sk_write_queue, skb);
1288}
1289
1290static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1291{
1292 __tcp_add_write_queue_tail(sk, skb);
1293
1294 /* Queue it, remembering where we must start sending. */
1295 if (sk->sk_send_head == NULL) {
1296 sk->sk_send_head = skb;
1297
1298 if (tcp_sk(sk)->highest_sack == NULL)
1299 tcp_sk(sk)->highest_sack = skb;
1300 }
1301}
1302
1303static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1304{
1305 __skb_queue_head(&sk->sk_write_queue, skb);
1306}
1307
1308/* Insert buff after skb on the write queue of sk. */
1309static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1310 struct sk_buff *buff,
1311 struct sock *sk)
1312{
1313 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1314}
1315
1316/* Insert new before skb on the write queue of sk. */
1317static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1318 struct sk_buff *skb,
1319 struct sock *sk)
1320{
1321 __skb_queue_before(&sk->sk_write_queue, skb, new);
1322
1323 if (sk->sk_send_head == skb)
1324 sk->sk_send_head = new;
1325}
1326
1327static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1328{
1329 __skb_unlink(skb, &sk->sk_write_queue);
1330}
1331
1332static inline int tcp_write_queue_empty(struct sock *sk)
1333{
1334 return skb_queue_empty(&sk->sk_write_queue);
1335}
1336
1337static inline void tcp_push_pending_frames(struct sock *sk)
1338{
1339 if (tcp_send_head(sk)) {
1340 struct tcp_sock *tp = tcp_sk(sk);
1341
1342 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1343 }
1344}
1345
1346/* Start sequence of the highest skb with SACKed bit, valid only if
1347 * sacked > 0 or when the caller has ensured validity by itself.
1348 */
1349static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1350{
1351 if (!tp->sacked_out)
1352 return tp->snd_una;
1353
1354 if (tp->highest_sack == NULL)
1355 return tp->snd_nxt;
1356
1357 return TCP_SKB_CB(tp->highest_sack)->seq;
1358}
1359
1360static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1361{
1362 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1363 tcp_write_queue_next(sk, skb);
1364}
1365
1366static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1367{
1368 return tcp_sk(sk)->highest_sack;
1369}
1370
1371static inline void tcp_highest_sack_reset(struct sock *sk)
1372{
1373 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1374}
1375
1376/* Called when old skb is about to be deleted (to be combined with new skb) */
1377static inline void tcp_highest_sack_combine(struct sock *sk,
1378 struct sk_buff *old,
1379 struct sk_buff *new)
1380{
1381 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1382 tcp_sk(sk)->highest_sack = new;
1383}
1384
1385/* Determines whether this is a thin stream (which may suffer from
1386 * increased latency). Used to trigger latency-reducing mechanisms.
1387 */
1388static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
1389{
1390 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1391}
1392
1393/* /proc */
1394enum tcp_seq_states {
1395 TCP_SEQ_STATE_LISTENING,
1396 TCP_SEQ_STATE_OPENREQ,
1397 TCP_SEQ_STATE_ESTABLISHED,
1398 TCP_SEQ_STATE_TIME_WAIT,
1399};
1400
1401struct tcp_seq_afinfo {
1402 char *name;
1403 sa_family_t family;
1404 struct file_operations seq_fops;
1405 struct seq_operations seq_ops;
1406};
1407
1408struct tcp_iter_state {
1409 struct seq_net_private p;
1410 sa_family_t family;
1411 enum tcp_seq_states state;
1412 struct sock *syn_wait_sk;
1413 int bucket, offset, sbucket, num, uid;
1414 loff_t last_pos;
1415};
1416
1417extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1418extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1419
1420extern struct request_sock_ops tcp_request_sock_ops;
1421extern struct request_sock_ops tcp6_request_sock_ops;
1422
1423extern void tcp_v4_destroy_sock(struct sock *sk);
1424
1425extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1426extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, u32 features);
1427extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1428 struct sk_buff *skb);
1429extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1430 struct sk_buff *skb);
1431extern int tcp_gro_complete(struct sk_buff *skb);
1432extern int tcp4_gro_complete(struct sk_buff *skb);
1433
1434#ifdef CONFIG_PROC_FS
1435extern int tcp4_proc_init(void);
1436extern void tcp4_proc_exit(void);
1437#endif
1438
1439/* TCP af-specific functions */
1440struct tcp_sock_af_ops {
1441#ifdef CONFIG_TCP_MD5SIG
1442 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1443 struct sock *addr_sk);
1444 int (*calc_md5_hash) (char *location,
1445 struct tcp_md5sig_key *md5,
1446 struct sock *sk,
1447 struct request_sock *req,
1448 struct sk_buff *skb);
1449 int (*md5_add) (struct sock *sk,
1450 struct sock *addr_sk,
1451 u8 *newkey,
1452 u8 len);
1453 int (*md5_parse) (struct sock *sk,
1454 char __user *optval,
1455 int optlen);
1456#endif
1457};
1458
1459struct tcp_request_sock_ops {
1460#ifdef CONFIG_TCP_MD5SIG
1461 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1462 struct request_sock *req);
1463 int (*calc_md5_hash) (char *location,
1464 struct tcp_md5sig_key *md5,
1465 struct sock *sk,
1466 struct request_sock *req,
1467 struct sk_buff *skb);
1468#endif
1469};
1470
1471/* Using SHA1 for now, define some constants.
1472 */
1473#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1474#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1475#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1476
1477extern int tcp_cookie_generator(u32 *bakery);
1478
1479/**
1480 * struct tcp_cookie_values - each socket needs extra space for the
1481 * cookies, together with (optional) space for any SYN data.
1482 *
1483 * A tcp_sock contains a pointer to the current value, and this is
1484 * cloned to the tcp_timewait_sock.
1485 *
1486 * @cookie_pair: variable data from the option exchange.
1487 *
1488 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1489 * indicates default (sysctl_tcp_cookie_size).
1490 * After cookie sent, remembers size of cookie.
1491 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1492 *
1493 * @s_data_desired: user specified tcpct_s_data_desired. When the
1494 * constant payload is specified (@s_data_constant),
1495 * holds its length instead.
1496 * Range 0 to TCP_MSS_DESIRED.
1497 *
1498 * @s_data_payload: constant data that is to be included in the
1499 * payload of SYN or SYNACK segments when the
1500 * cookie option is present.
1501 */
1502struct tcp_cookie_values {
1503 struct kref kref;
1504 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1505 u8 cookie_pair_size;
1506 u8 cookie_desired;
1507 u16 s_data_desired:11,
1508 s_data_constant:1,
1509 s_data_in:1,
1510 s_data_out:1,
1511 s_data_unused:2;
1512 u8 s_data_payload[0];
1513};
1514
1515static inline void tcp_cookie_values_release(struct kref *kref)
1516{
1517 kfree(container_of(kref, struct tcp_cookie_values, kref));
1518}
1519
1520/* The length of constant payload data. Note that s_data_desired is
1521 * overloaded, depending on s_data_constant: either the length of constant
1522 * data (returned here) or the limit on variable data.
1523 */
1524static inline int tcp_s_data_size(const struct tcp_sock *tp)
1525{
1526 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1527 ? tp->cookie_values->s_data_desired
1528 : 0;
1529}
1530
1531/**
1532 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1533 *
1534 * As tcp_request_sock has already been extended in other places, the
1535 * only remaining method is to pass stack values along as function
1536 * parameters. These parameters are not needed after sending SYNACK.
1537 *
1538 * @cookie_bakery: cryptographic secret and message workspace.
1539 *
1540 * @cookie_plus: bytes in authenticator/cookie option, copied from
1541 * struct tcp_options_received (above).
1542 */
1543struct tcp_extend_values {
1544 struct request_values rv;
1545 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1546 u8 cookie_plus:6,
1547 cookie_out_never:1,
1548 cookie_in_always:1;
1549};
1550
1551static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1552{
1553 return (struct tcp_extend_values *)rvp;
1554}
1555
1556extern void tcp_v4_init(void);
1557extern void tcp_init(void);
1558
1559#endif /* _TCP_H */
1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define FASTRETRANS_DEBUG 1
22
23#include <linux/list.h>
24#include <linux/tcp.h>
25#include <linux/bug.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
29#include <linux/skbuff.h>
30#include <linux/cryptohash.h>
31#include <linux/kref.h>
32#include <linux/ktime.h>
33
34#include <net/inet_connection_sock.h>
35#include <net/inet_timewait_sock.h>
36#include <net/inet_hashtables.h>
37#include <net/checksum.h>
38#include <net/request_sock.h>
39#include <net/sock.h>
40#include <net/snmp.h>
41#include <net/ip.h>
42#include <net/tcp_states.h>
43#include <net/inet_ecn.h>
44#include <net/dst.h>
45
46#include <linux/seq_file.h>
47#include <linux/memcontrol.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER (128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56
57/*
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
60 */
61#define MAX_TCP_WINDOW 32767U
62
63/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
64#define TCP_MIN_MSS 88U
65
66/* The least MTU to use for probing */
67#define TCP_BASE_MSS 1024
68
69/* probing interval, default to 10 minutes as per RFC4821 */
70#define TCP_PROBE_INTERVAL 600
71
72/* Specify interval when tcp mtu probing will stop */
73#define TCP_PROBE_THRESHOLD 8
74
75/* After receiving this amount of duplicate ACKs fast retransmit starts. */
76#define TCP_FASTRETRANS_THRESH 3
77
78/* Maximal number of ACKs sent quickly to accelerate slow-start. */
79#define TCP_MAX_QUICKACKS 16U
80
81/* urg_data states */
82#define TCP_URG_VALID 0x0100
83#define TCP_URG_NOTYET 0x0200
84#define TCP_URG_READ 0x0400
85
86#define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
91 */
92
93#define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
98 */
99
100#define TCP_SYN_RETRIES 6 /* This is how many retries are done
101 * when active opening a connection.
102 * RFC1122 says the minimum retry MUST
103 * be at least 180secs. Nevertheless
104 * this value is corresponding to
105 * 63secs of retransmission with the
106 * current initial RTO.
107 */
108
109#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
110 * when passive opening a connection.
111 * This is corresponding to 31secs of
112 * retransmission with the current
113 * initial RTO.
114 */
115
116#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
117 * state, about 60 seconds */
118#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
119 /* BSD style FIN_WAIT2 deadlock breaker.
120 * It used to be 3min, new value is 60sec,
121 * to combine FIN-WAIT-2 timeout with
122 * TIME-WAIT timer.
123 */
124
125#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
126#if HZ >= 100
127#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
128#define TCP_ATO_MIN ((unsigned)(HZ/25))
129#else
130#define TCP_DELACK_MIN 4U
131#define TCP_ATO_MIN 4U
132#endif
133#define TCP_RTO_MAX ((unsigned)(120*HZ))
134#define TCP_RTO_MIN ((unsigned)(HZ/5))
135#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
136#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
137 * used as a fallback RTO for the
138 * initial data transmission if no
139 * valid RTT sample has been acquired,
140 * most likely due to retrans in 3WHS.
141 */
142
143#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
144 * for local resources.
145 */
146
147#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
148#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
149#define TCP_KEEPALIVE_INTVL (75*HZ)
150
151#define MAX_TCP_KEEPIDLE 32767
152#define MAX_TCP_KEEPINTVL 32767
153#define MAX_TCP_KEEPCNT 127
154#define MAX_TCP_SYNCNT 127
155
156#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
157
158#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
159#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
160 * after this time. It should be equal
161 * (or greater than) TCP_TIMEWAIT_LEN
162 * to provide reliability equal to one
163 * provided by timewait state.
164 */
165#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
166 * timestamps. It must be less than
167 * minimal timewait lifetime.
168 */
169/*
170 * TCP option
171 */
172
173#define TCPOPT_NOP 1 /* Padding */
174#define TCPOPT_EOL 0 /* End of options */
175#define TCPOPT_MSS 2 /* Segment size negotiating */
176#define TCPOPT_WINDOW 3 /* Window scaling */
177#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
178#define TCPOPT_SACK 5 /* SACK Block */
179#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
180#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
181#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
182#define TCPOPT_EXP 254 /* Experimental */
183/* Magic number to be after the option value for sharing TCP
184 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
185 */
186#define TCPOPT_FASTOPEN_MAGIC 0xF989
187
188/*
189 * TCP option lengths
190 */
191
192#define TCPOLEN_MSS 4
193#define TCPOLEN_WINDOW 3
194#define TCPOLEN_SACK_PERM 2
195#define TCPOLEN_TIMESTAMP 10
196#define TCPOLEN_MD5SIG 18
197#define TCPOLEN_FASTOPEN_BASE 2
198#define TCPOLEN_EXP_FASTOPEN_BASE 4
199
200/* But this is what stacks really send out. */
201#define TCPOLEN_TSTAMP_ALIGNED 12
202#define TCPOLEN_WSCALE_ALIGNED 4
203#define TCPOLEN_SACKPERM_ALIGNED 4
204#define TCPOLEN_SACK_BASE 2
205#define TCPOLEN_SACK_BASE_ALIGNED 4
206#define TCPOLEN_SACK_PERBLOCK 8
207#define TCPOLEN_MD5SIG_ALIGNED 20
208#define TCPOLEN_MSS_ALIGNED 4
209
210/* Flags in tp->nonagle */
211#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
212#define TCP_NAGLE_CORK 2 /* Socket is corked */
213#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
214
215/* TCP thin-stream limits */
216#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
217
218/* TCP initial congestion window as per rfc6928 */
219#define TCP_INIT_CWND 10
220
221/* Bit Flags for sysctl_tcp_fastopen */
222#define TFO_CLIENT_ENABLE 1
223#define TFO_SERVER_ENABLE 2
224#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
225
226/* Accept SYN data w/o any cookie option */
227#define TFO_SERVER_COOKIE_NOT_REQD 0x200
228
229/* Force enable TFO on all listeners, i.e., not requiring the
230 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
231 */
232#define TFO_SERVER_WO_SOCKOPT1 0x400
233#define TFO_SERVER_WO_SOCKOPT2 0x800
234
235extern struct inet_timewait_death_row tcp_death_row;
236
237/* sysctl variables for tcp */
238extern int sysctl_tcp_timestamps;
239extern int sysctl_tcp_window_scaling;
240extern int sysctl_tcp_sack;
241extern int sysctl_tcp_fastopen;
242extern int sysctl_tcp_retrans_collapse;
243extern int sysctl_tcp_stdurg;
244extern int sysctl_tcp_rfc1337;
245extern int sysctl_tcp_abort_on_overflow;
246extern int sysctl_tcp_max_orphans;
247extern int sysctl_tcp_fack;
248extern int sysctl_tcp_reordering;
249extern int sysctl_tcp_max_reordering;
250extern int sysctl_tcp_dsack;
251extern long sysctl_tcp_mem[3];
252extern int sysctl_tcp_wmem[3];
253extern int sysctl_tcp_rmem[3];
254extern int sysctl_tcp_app_win;
255extern int sysctl_tcp_adv_win_scale;
256extern int sysctl_tcp_tw_reuse;
257extern int sysctl_tcp_frto;
258extern int sysctl_tcp_low_latency;
259extern int sysctl_tcp_nometrics_save;
260extern int sysctl_tcp_moderate_rcvbuf;
261extern int sysctl_tcp_tso_win_divisor;
262extern int sysctl_tcp_workaround_signed_windows;
263extern int sysctl_tcp_slow_start_after_idle;
264extern int sysctl_tcp_thin_linear_timeouts;
265extern int sysctl_tcp_thin_dupack;
266extern int sysctl_tcp_early_retrans;
267extern int sysctl_tcp_limit_output_bytes;
268extern int sysctl_tcp_challenge_ack_limit;
269extern int sysctl_tcp_min_tso_segs;
270extern int sysctl_tcp_min_rtt_wlen;
271extern int sysctl_tcp_autocorking;
272extern int sysctl_tcp_invalid_ratelimit;
273extern int sysctl_tcp_pacing_ss_ratio;
274extern int sysctl_tcp_pacing_ca_ratio;
275
276extern atomic_long_t tcp_memory_allocated;
277extern struct percpu_counter tcp_sockets_allocated;
278extern int tcp_memory_pressure;
279
280/* optimized version of sk_under_memory_pressure() for TCP sockets */
281static inline bool tcp_under_memory_pressure(const struct sock *sk)
282{
283 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
284 mem_cgroup_under_socket_pressure(sk->sk_memcg))
285 return true;
286
287 return tcp_memory_pressure;
288}
289/*
290 * The next routines deal with comparing 32 bit unsigned ints
291 * and worry about wraparound (automatic with unsigned arithmetic).
292 */
293
294static inline bool before(__u32 seq1, __u32 seq2)
295{
296 return (__s32)(seq1-seq2) < 0;
297}
298#define after(seq2, seq1) before(seq1, seq2)
299
300/* is s2<=s1<=s3 ? */
301static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
302{
303 return seq3 - seq2 >= seq1 - seq2;
304}
305
306static inline bool tcp_out_of_memory(struct sock *sk)
307{
308 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
309 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
310 return true;
311 return false;
312}
313
314void sk_forced_mem_schedule(struct sock *sk, int size);
315
316static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
317{
318 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
319 int orphans = percpu_counter_read_positive(ocp);
320
321 if (orphans << shift > sysctl_tcp_max_orphans) {
322 orphans = percpu_counter_sum_positive(ocp);
323 if (orphans << shift > sysctl_tcp_max_orphans)
324 return true;
325 }
326 return false;
327}
328
329bool tcp_check_oom(struct sock *sk, int shift);
330
331
332extern struct proto tcp_prot;
333
334#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
335#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
336#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
337#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
338#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
339
340void tcp_tasklet_init(void);
341
342void tcp_v4_err(struct sk_buff *skb, u32);
343
344void tcp_shutdown(struct sock *sk, int how);
345
346void tcp_v4_early_demux(struct sk_buff *skb);
347int tcp_v4_rcv(struct sk_buff *skb);
348
349int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
350int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
351int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
352 int flags);
353void tcp_release_cb(struct sock *sk);
354void tcp_wfree(struct sk_buff *skb);
355void tcp_write_timer_handler(struct sock *sk);
356void tcp_delack_timer_handler(struct sock *sk);
357int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
358int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
359void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
360 const struct tcphdr *th, unsigned int len);
361void tcp_rcv_space_adjust(struct sock *sk);
362int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
363void tcp_twsk_destructor(struct sock *sk);
364ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
365 struct pipe_inode_info *pipe, size_t len,
366 unsigned int flags);
367
368static inline void tcp_dec_quickack_mode(struct sock *sk,
369 const unsigned int pkts)
370{
371 struct inet_connection_sock *icsk = inet_csk(sk);
372
373 if (icsk->icsk_ack.quick) {
374 if (pkts >= icsk->icsk_ack.quick) {
375 icsk->icsk_ack.quick = 0;
376 /* Leaving quickack mode we deflate ATO. */
377 icsk->icsk_ack.ato = TCP_ATO_MIN;
378 } else
379 icsk->icsk_ack.quick -= pkts;
380 }
381}
382
383#define TCP_ECN_OK 1
384#define TCP_ECN_QUEUE_CWR 2
385#define TCP_ECN_DEMAND_CWR 4
386#define TCP_ECN_SEEN 8
387
388enum tcp_tw_status {
389 TCP_TW_SUCCESS = 0,
390 TCP_TW_RST = 1,
391 TCP_TW_ACK = 2,
392 TCP_TW_SYN = 3
393};
394
395
396enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
397 struct sk_buff *skb,
398 const struct tcphdr *th);
399struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
400 struct request_sock *req, bool fastopen);
401int tcp_child_process(struct sock *parent, struct sock *child,
402 struct sk_buff *skb);
403void tcp_enter_loss(struct sock *sk);
404void tcp_clear_retrans(struct tcp_sock *tp);
405void tcp_update_metrics(struct sock *sk);
406void tcp_init_metrics(struct sock *sk);
407void tcp_metrics_init(void);
408bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
409 bool paws_check, bool timestamps);
410bool tcp_remember_stamp(struct sock *sk);
411bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
412void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
413void tcp_disable_fack(struct tcp_sock *tp);
414void tcp_close(struct sock *sk, long timeout);
415void tcp_init_sock(struct sock *sk);
416unsigned int tcp_poll(struct file *file, struct socket *sock,
417 struct poll_table_struct *wait);
418int tcp_getsockopt(struct sock *sk, int level, int optname,
419 char __user *optval, int __user *optlen);
420int tcp_setsockopt(struct sock *sk, int level, int optname,
421 char __user *optval, unsigned int optlen);
422int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
423 char __user *optval, int __user *optlen);
424int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
425 char __user *optval, unsigned int optlen);
426void tcp_set_keepalive(struct sock *sk, int val);
427void tcp_syn_ack_timeout(const struct request_sock *req);
428int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
429 int flags, int *addr_len);
430void tcp_parse_options(const struct sk_buff *skb,
431 struct tcp_options_received *opt_rx,
432 int estab, struct tcp_fastopen_cookie *foc);
433const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
434
435/*
436 * TCP v4 functions exported for the inet6 API
437 */
438
439void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
440void tcp_v4_mtu_reduced(struct sock *sk);
441void tcp_req_err(struct sock *sk, u32 seq, bool abort);
442int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
443struct sock *tcp_create_openreq_child(const struct sock *sk,
444 struct request_sock *req,
445 struct sk_buff *skb);
446void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
447struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
448 struct request_sock *req,
449 struct dst_entry *dst,
450 struct request_sock *req_unhash,
451 bool *own_req);
452int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
453int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
454int tcp_connect(struct sock *sk);
455struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
456 struct request_sock *req,
457 struct tcp_fastopen_cookie *foc,
458 bool attach_req);
459int tcp_disconnect(struct sock *sk, int flags);
460
461void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
462int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
463void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
464
465/* From syncookies.c */
466struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
467 struct request_sock *req,
468 struct dst_entry *dst);
469int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
470 u32 cookie);
471struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
472#ifdef CONFIG_SYN_COOKIES
473
474/* Syncookies use a monotonic timer which increments every 60 seconds.
475 * This counter is used both as a hash input and partially encoded into
476 * the cookie value. A cookie is only validated further if the delta
477 * between the current counter value and the encoded one is less than this,
478 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
479 * the counter advances immediately after a cookie is generated).
480 */
481#define MAX_SYNCOOKIE_AGE 2
482#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
483#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
484
485/* syncookies: remember time of last synqueue overflow
486 * But do not dirty this field too often (once per second is enough)
487 * It is racy as we do not hold a lock, but race is very minor.
488 */
489static inline void tcp_synq_overflow(const struct sock *sk)
490{
491 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
492 unsigned long now = jiffies;
493
494 if (time_after(now, last_overflow + HZ))
495 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
496}
497
498/* syncookies: no recent synqueue overflow on this listening socket? */
499static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
500{
501 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
502
503 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
504}
505
506static inline u32 tcp_cookie_time(void)
507{
508 u64 val = get_jiffies_64();
509
510 do_div(val, TCP_SYNCOOKIE_PERIOD);
511 return val;
512}
513
514u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
515 u16 *mssp);
516__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
517__u32 cookie_init_timestamp(struct request_sock *req);
518bool cookie_timestamp_decode(struct tcp_options_received *opt);
519bool cookie_ecn_ok(const struct tcp_options_received *opt,
520 const struct net *net, const struct dst_entry *dst);
521
522/* From net/ipv6/syncookies.c */
523int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
524 u32 cookie);
525struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
526
527u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
528 const struct tcphdr *th, u16 *mssp);
529__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
530#endif
531/* tcp_output.c */
532
533void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
534 int nonagle);
535bool tcp_may_send_now(struct sock *sk);
536int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
537int tcp_retransmit_skb(struct sock *, struct sk_buff *);
538void tcp_retransmit_timer(struct sock *sk);
539void tcp_xmit_retransmit_queue(struct sock *);
540void tcp_simple_retransmit(struct sock *);
541int tcp_trim_head(struct sock *, struct sk_buff *, u32);
542int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
543
544void tcp_send_probe0(struct sock *);
545void tcp_send_partial(struct sock *);
546int tcp_write_wakeup(struct sock *, int mib);
547void tcp_send_fin(struct sock *sk);
548void tcp_send_active_reset(struct sock *sk, gfp_t priority);
549int tcp_send_synack(struct sock *);
550void tcp_push_one(struct sock *, unsigned int mss_now);
551void tcp_send_ack(struct sock *sk);
552void tcp_send_delayed_ack(struct sock *sk);
553void tcp_send_loss_probe(struct sock *sk);
554bool tcp_schedule_loss_probe(struct sock *sk);
555void tcp_skb_collapse_tstamp(struct sk_buff *skb,
556 const struct sk_buff *next_skb);
557
558/* tcp_input.c */
559void tcp_resume_early_retransmit(struct sock *sk);
560void tcp_rearm_rto(struct sock *sk);
561void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
562void tcp_reset(struct sock *sk);
563void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
564void tcp_fin(struct sock *sk);
565
566/* tcp_timer.c */
567void tcp_init_xmit_timers(struct sock *);
568static inline void tcp_clear_xmit_timers(struct sock *sk)
569{
570 inet_csk_clear_xmit_timers(sk);
571}
572
573unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
574unsigned int tcp_current_mss(struct sock *sk);
575
576/* Bound MSS / TSO packet size with the half of the window */
577static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
578{
579 int cutoff;
580
581 /* When peer uses tiny windows, there is no use in packetizing
582 * to sub-MSS pieces for the sake of SWS or making sure there
583 * are enough packets in the pipe for fast recovery.
584 *
585 * On the other hand, for extremely large MSS devices, handling
586 * smaller than MSS windows in this way does make sense.
587 */
588 if (tp->max_window >= 512)
589 cutoff = (tp->max_window >> 1);
590 else
591 cutoff = tp->max_window;
592
593 if (cutoff && pktsize > cutoff)
594 return max_t(int, cutoff, 68U - tp->tcp_header_len);
595 else
596 return pktsize;
597}
598
599/* tcp.c */
600void tcp_get_info(struct sock *, struct tcp_info *);
601
602/* Read 'sendfile()'-style from a TCP socket */
603typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
604 unsigned int, size_t);
605int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
606 sk_read_actor_t recv_actor);
607
608void tcp_initialize_rcv_mss(struct sock *sk);
609
610int tcp_mtu_to_mss(struct sock *sk, int pmtu);
611int tcp_mss_to_mtu(struct sock *sk, int mss);
612void tcp_mtup_init(struct sock *sk);
613void tcp_init_buffer_space(struct sock *sk);
614
615static inline void tcp_bound_rto(const struct sock *sk)
616{
617 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
618 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
619}
620
621static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
622{
623 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
624}
625
626static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
627{
628 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
629 ntohl(TCP_FLAG_ACK) |
630 snd_wnd);
631}
632
633static inline void tcp_fast_path_on(struct tcp_sock *tp)
634{
635 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
636}
637
638static inline void tcp_fast_path_check(struct sock *sk)
639{
640 struct tcp_sock *tp = tcp_sk(sk);
641
642 if (skb_queue_empty(&tp->out_of_order_queue) &&
643 tp->rcv_wnd &&
644 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
645 !tp->urg_data)
646 tcp_fast_path_on(tp);
647}
648
649/* Compute the actual rto_min value */
650static inline u32 tcp_rto_min(struct sock *sk)
651{
652 const struct dst_entry *dst = __sk_dst_get(sk);
653 u32 rto_min = TCP_RTO_MIN;
654
655 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
656 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
657 return rto_min;
658}
659
660static inline u32 tcp_rto_min_us(struct sock *sk)
661{
662 return jiffies_to_usecs(tcp_rto_min(sk));
663}
664
665static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
666{
667 return dst_metric_locked(dst, RTAX_CC_ALGO);
668}
669
670/* Minimum RTT in usec. ~0 means not available. */
671static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
672{
673 return tp->rtt_min[0].rtt;
674}
675
676/* Compute the actual receive window we are currently advertising.
677 * Rcv_nxt can be after the window if our peer push more data
678 * than the offered window.
679 */
680static inline u32 tcp_receive_window(const struct tcp_sock *tp)
681{
682 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
683
684 if (win < 0)
685 win = 0;
686 return (u32) win;
687}
688
689/* Choose a new window, without checks for shrinking, and without
690 * scaling applied to the result. The caller does these things
691 * if necessary. This is a "raw" window selection.
692 */
693u32 __tcp_select_window(struct sock *sk);
694
695void tcp_send_window_probe(struct sock *sk);
696
697/* TCP timestamps are only 32-bits, this causes a slight
698 * complication on 64-bit systems since we store a snapshot
699 * of jiffies in the buffer control blocks below. We decided
700 * to use only the low 32-bits of jiffies and hide the ugly
701 * casts with the following macro.
702 */
703#define tcp_time_stamp ((__u32)(jiffies))
704
705static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
706{
707 return skb->skb_mstamp.stamp_jiffies;
708}
709
710
711#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
712
713#define TCPHDR_FIN 0x01
714#define TCPHDR_SYN 0x02
715#define TCPHDR_RST 0x04
716#define TCPHDR_PSH 0x08
717#define TCPHDR_ACK 0x10
718#define TCPHDR_URG 0x20
719#define TCPHDR_ECE 0x40
720#define TCPHDR_CWR 0x80
721
722#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
723
724/* This is what the send packet queuing engine uses to pass
725 * TCP per-packet control information to the transmission code.
726 * We also store the host-order sequence numbers in here too.
727 * This is 44 bytes if IPV6 is enabled.
728 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
729 */
730struct tcp_skb_cb {
731 __u32 seq; /* Starting sequence number */
732 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
733 union {
734 /* Note : tcp_tw_isn is used in input path only
735 * (isn chosen by tcp_timewait_state_process())
736 *
737 * tcp_gso_segs/size are used in write queue only,
738 * cf tcp_skb_pcount()/tcp_skb_mss()
739 */
740 __u32 tcp_tw_isn;
741 struct {
742 u16 tcp_gso_segs;
743 u16 tcp_gso_size;
744 };
745 };
746 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
747
748 __u8 sacked; /* State flags for SACK/FACK. */
749#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
750#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
751#define TCPCB_LOST 0x04 /* SKB is lost */
752#define TCPCB_TAGBITS 0x07 /* All tag bits */
753#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
754#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
755#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
756 TCPCB_REPAIRED)
757
758 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
759 /* 1 byte hole */
760 __u32 ack_seq; /* Sequence number ACK'd */
761 union {
762 struct inet_skb_parm h4;
763#if IS_ENABLED(CONFIG_IPV6)
764 struct inet6_skb_parm h6;
765#endif
766 } header; /* For incoming frames */
767};
768
769#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
770
771
772#if IS_ENABLED(CONFIG_IPV6)
773/* This is the variant of inet6_iif() that must be used by TCP,
774 * as TCP moves IP6CB into a different location in skb->cb[]
775 */
776static inline int tcp_v6_iif(const struct sk_buff *skb)
777{
778 return TCP_SKB_CB(skb)->header.h6.iif;
779}
780#endif
781
782/* Due to TSO, an SKB can be composed of multiple actual
783 * packets. To keep these tracked properly, we use this.
784 */
785static inline int tcp_skb_pcount(const struct sk_buff *skb)
786{
787 return TCP_SKB_CB(skb)->tcp_gso_segs;
788}
789
790static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
791{
792 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
793}
794
795static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
796{
797 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
798}
799
800/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
801static inline int tcp_skb_mss(const struct sk_buff *skb)
802{
803 return TCP_SKB_CB(skb)->tcp_gso_size;
804}
805
806/* Events passed to congestion control interface */
807enum tcp_ca_event {
808 CA_EVENT_TX_START, /* first transmit when no packets in flight */
809 CA_EVENT_CWND_RESTART, /* congestion window restart */
810 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
811 CA_EVENT_LOSS, /* loss timeout */
812 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
813 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
814 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
815 CA_EVENT_NON_DELAYED_ACK,
816};
817
818/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
819enum tcp_ca_ack_event_flags {
820 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
821 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
822 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
823};
824
825/*
826 * Interface for adding new TCP congestion control handlers
827 */
828#define TCP_CA_NAME_MAX 16
829#define TCP_CA_MAX 128
830#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
831
832#define TCP_CA_UNSPEC 0
833
834/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
835#define TCP_CONG_NON_RESTRICTED 0x1
836/* Requires ECN/ECT set on all packets */
837#define TCP_CONG_NEEDS_ECN 0x2
838
839union tcp_cc_info;
840
841struct tcp_congestion_ops {
842 struct list_head list;
843 u32 key;
844 u32 flags;
845
846 /* initialize private data (optional) */
847 void (*init)(struct sock *sk);
848 /* cleanup private data (optional) */
849 void (*release)(struct sock *sk);
850
851 /* return slow start threshold (required) */
852 u32 (*ssthresh)(struct sock *sk);
853 /* do new cwnd calculation (required) */
854 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
855 /* call before changing ca_state (optional) */
856 void (*set_state)(struct sock *sk, u8 new_state);
857 /* call when cwnd event occurs (optional) */
858 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
859 /* call when ack arrives (optional) */
860 void (*in_ack_event)(struct sock *sk, u32 flags);
861 /* new value of cwnd after loss (optional) */
862 u32 (*undo_cwnd)(struct sock *sk);
863 /* hook for packet ack accounting (optional) */
864 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
865 /* get info for inet_diag (optional) */
866 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
867 union tcp_cc_info *info);
868
869 char name[TCP_CA_NAME_MAX];
870 struct module *owner;
871};
872
873int tcp_register_congestion_control(struct tcp_congestion_ops *type);
874void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
875
876void tcp_assign_congestion_control(struct sock *sk);
877void tcp_init_congestion_control(struct sock *sk);
878void tcp_cleanup_congestion_control(struct sock *sk);
879int tcp_set_default_congestion_control(const char *name);
880void tcp_get_default_congestion_control(char *name);
881void tcp_get_available_congestion_control(char *buf, size_t len);
882void tcp_get_allowed_congestion_control(char *buf, size_t len);
883int tcp_set_allowed_congestion_control(char *allowed);
884int tcp_set_congestion_control(struct sock *sk, const char *name);
885u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
886void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
887
888u32 tcp_reno_ssthresh(struct sock *sk);
889void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
890extern struct tcp_congestion_ops tcp_reno;
891
892struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
893u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
894#ifdef CONFIG_INET
895char *tcp_ca_get_name_by_key(u32 key, char *buffer);
896#else
897static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
898{
899 return NULL;
900}
901#endif
902
903static inline bool tcp_ca_needs_ecn(const struct sock *sk)
904{
905 const struct inet_connection_sock *icsk = inet_csk(sk);
906
907 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
908}
909
910static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
911{
912 struct inet_connection_sock *icsk = inet_csk(sk);
913
914 if (icsk->icsk_ca_ops->set_state)
915 icsk->icsk_ca_ops->set_state(sk, ca_state);
916 icsk->icsk_ca_state = ca_state;
917}
918
919static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
920{
921 const struct inet_connection_sock *icsk = inet_csk(sk);
922
923 if (icsk->icsk_ca_ops->cwnd_event)
924 icsk->icsk_ca_ops->cwnd_event(sk, event);
925}
926
927/* These functions determine how the current flow behaves in respect of SACK
928 * handling. SACK is negotiated with the peer, and therefore it can vary
929 * between different flows.
930 *
931 * tcp_is_sack - SACK enabled
932 * tcp_is_reno - No SACK
933 * tcp_is_fack - FACK enabled, implies SACK enabled
934 */
935static inline int tcp_is_sack(const struct tcp_sock *tp)
936{
937 return tp->rx_opt.sack_ok;
938}
939
940static inline bool tcp_is_reno(const struct tcp_sock *tp)
941{
942 return !tcp_is_sack(tp);
943}
944
945static inline bool tcp_is_fack(const struct tcp_sock *tp)
946{
947 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
948}
949
950static inline void tcp_enable_fack(struct tcp_sock *tp)
951{
952 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
953}
954
955/* TCP early-retransmit (ER) is similar to but more conservative than
956 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
957 */
958static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
959{
960 struct net *net = sock_net((struct sock *)tp);
961
962 tp->do_early_retrans = sysctl_tcp_early_retrans &&
963 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
964 net->ipv4.sysctl_tcp_reordering == 3;
965}
966
967static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
968{
969 tp->do_early_retrans = 0;
970}
971
972static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
973{
974 return tp->sacked_out + tp->lost_out;
975}
976
977/* This determines how many packets are "in the network" to the best
978 * of our knowledge. In many cases it is conservative, but where
979 * detailed information is available from the receiver (via SACK
980 * blocks etc.) we can make more aggressive calculations.
981 *
982 * Use this for decisions involving congestion control, use just
983 * tp->packets_out to determine if the send queue is empty or not.
984 *
985 * Read this equation as:
986 *
987 * "Packets sent once on transmission queue" MINUS
988 * "Packets left network, but not honestly ACKed yet" PLUS
989 * "Packets fast retransmitted"
990 */
991static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
992{
993 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
994}
995
996#define TCP_INFINITE_SSTHRESH 0x7fffffff
997
998static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
999{
1000 return tp->snd_cwnd < tp->snd_ssthresh;
1001}
1002
1003static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1004{
1005 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1006}
1007
1008static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1009{
1010 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1011 (1 << inet_csk(sk)->icsk_ca_state);
1012}
1013
1014/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1015 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1016 * ssthresh.
1017 */
1018static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1019{
1020 const struct tcp_sock *tp = tcp_sk(sk);
1021
1022 if (tcp_in_cwnd_reduction(sk))
1023 return tp->snd_ssthresh;
1024 else
1025 return max(tp->snd_ssthresh,
1026 ((tp->snd_cwnd >> 1) +
1027 (tp->snd_cwnd >> 2)));
1028}
1029
1030/* Use define here intentionally to get WARN_ON location shown at the caller */
1031#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1032
1033void tcp_enter_cwr(struct sock *sk);
1034__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1035
1036/* The maximum number of MSS of available cwnd for which TSO defers
1037 * sending if not using sysctl_tcp_tso_win_divisor.
1038 */
1039static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1040{
1041 return 3;
1042}
1043
1044/* Slow start with delack produces 3 packets of burst, so that
1045 * it is safe "de facto". This will be the default - same as
1046 * the default reordering threshold - but if reordering increases,
1047 * we must be able to allow cwnd to burst at least this much in order
1048 * to not pull it back when holes are filled.
1049 */
1050static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
1051{
1052 return tp->reordering;
1053}
1054
1055/* Returns end sequence number of the receiver's advertised window */
1056static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1057{
1058 return tp->snd_una + tp->snd_wnd;
1059}
1060
1061/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1062 * flexible approach. The RFC suggests cwnd should not be raised unless
1063 * it was fully used previously. And that's exactly what we do in
1064 * congestion avoidance mode. But in slow start we allow cwnd to grow
1065 * as long as the application has used half the cwnd.
1066 * Example :
1067 * cwnd is 10 (IW10), but application sends 9 frames.
1068 * We allow cwnd to reach 18 when all frames are ACKed.
1069 * This check is safe because it's as aggressive as slow start which already
1070 * risks 100% overshoot. The advantage is that we discourage application to
1071 * either send more filler packets or data to artificially blow up the cwnd
1072 * usage, and allow application-limited process to probe bw more aggressively.
1073 */
1074static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1075{
1076 const struct tcp_sock *tp = tcp_sk(sk);
1077
1078 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1079 if (tcp_in_slow_start(tp))
1080 return tp->snd_cwnd < 2 * tp->max_packets_out;
1081
1082 return tp->is_cwnd_limited;
1083}
1084
1085/* Something is really bad, we could not queue an additional packet,
1086 * because qdisc is full or receiver sent a 0 window.
1087 * We do not want to add fuel to the fire, or abort too early,
1088 * so make sure the timer we arm now is at least 200ms in the future,
1089 * regardless of current icsk_rto value (as it could be ~2ms)
1090 */
1091static inline unsigned long tcp_probe0_base(const struct sock *sk)
1092{
1093 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1094}
1095
1096/* Variant of inet_csk_rto_backoff() used for zero window probes */
1097static inline unsigned long tcp_probe0_when(const struct sock *sk,
1098 unsigned long max_when)
1099{
1100 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1101
1102 return (unsigned long)min_t(u64, when, max_when);
1103}
1104
1105static inline void tcp_check_probe_timer(struct sock *sk)
1106{
1107 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1108 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1109 tcp_probe0_base(sk), TCP_RTO_MAX);
1110}
1111
1112static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1113{
1114 tp->snd_wl1 = seq;
1115}
1116
1117static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1118{
1119 tp->snd_wl1 = seq;
1120}
1121
1122/*
1123 * Calculate(/check) TCP checksum
1124 */
1125static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1126 __be32 daddr, __wsum base)
1127{
1128 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1129}
1130
1131static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1132{
1133 return __skb_checksum_complete(skb);
1134}
1135
1136static inline bool tcp_checksum_complete(struct sk_buff *skb)
1137{
1138 return !skb_csum_unnecessary(skb) &&
1139 __tcp_checksum_complete(skb);
1140}
1141
1142/* Prequeue for VJ style copy to user, combined with checksumming. */
1143
1144static inline void tcp_prequeue_init(struct tcp_sock *tp)
1145{
1146 tp->ucopy.task = NULL;
1147 tp->ucopy.len = 0;
1148 tp->ucopy.memory = 0;
1149 skb_queue_head_init(&tp->ucopy.prequeue);
1150}
1151
1152bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1153
1154#undef STATE_TRACE
1155
1156#ifdef STATE_TRACE
1157static const char *statename[]={
1158 "Unused","Established","Syn Sent","Syn Recv",
1159 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1160 "Close Wait","Last ACK","Listen","Closing"
1161};
1162#endif
1163void tcp_set_state(struct sock *sk, int state);
1164
1165void tcp_done(struct sock *sk);
1166
1167int tcp_abort(struct sock *sk, int err);
1168
1169static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1170{
1171 rx_opt->dsack = 0;
1172 rx_opt->num_sacks = 0;
1173}
1174
1175u32 tcp_default_init_rwnd(u32 mss);
1176void tcp_cwnd_restart(struct sock *sk, s32 delta);
1177
1178static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1179{
1180 struct tcp_sock *tp = tcp_sk(sk);
1181 s32 delta;
1182
1183 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out)
1184 return;
1185 delta = tcp_time_stamp - tp->lsndtime;
1186 if (delta > inet_csk(sk)->icsk_rto)
1187 tcp_cwnd_restart(sk, delta);
1188}
1189
1190/* Determine a window scaling and initial window to offer. */
1191void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1192 __u32 *window_clamp, int wscale_ok,
1193 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1194
1195static inline int tcp_win_from_space(int space)
1196{
1197 return sysctl_tcp_adv_win_scale<=0 ?
1198 (space>>(-sysctl_tcp_adv_win_scale)) :
1199 space - (space>>sysctl_tcp_adv_win_scale);
1200}
1201
1202/* Note: caller must be prepared to deal with negative returns */
1203static inline int tcp_space(const struct sock *sk)
1204{
1205 return tcp_win_from_space(sk->sk_rcvbuf -
1206 atomic_read(&sk->sk_rmem_alloc));
1207}
1208
1209static inline int tcp_full_space(const struct sock *sk)
1210{
1211 return tcp_win_from_space(sk->sk_rcvbuf);
1212}
1213
1214extern void tcp_openreq_init_rwin(struct request_sock *req,
1215 const struct sock *sk_listener,
1216 const struct dst_entry *dst);
1217
1218void tcp_enter_memory_pressure(struct sock *sk);
1219
1220static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1221{
1222 struct net *net = sock_net((struct sock *)tp);
1223
1224 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1225}
1226
1227static inline int keepalive_time_when(const struct tcp_sock *tp)
1228{
1229 struct net *net = sock_net((struct sock *)tp);
1230
1231 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1232}
1233
1234static inline int keepalive_probes(const struct tcp_sock *tp)
1235{
1236 struct net *net = sock_net((struct sock *)tp);
1237
1238 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1239}
1240
1241static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1242{
1243 const struct inet_connection_sock *icsk = &tp->inet_conn;
1244
1245 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1246 tcp_time_stamp - tp->rcv_tstamp);
1247}
1248
1249static inline int tcp_fin_time(const struct sock *sk)
1250{
1251 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1252 const int rto = inet_csk(sk)->icsk_rto;
1253
1254 if (fin_timeout < (rto << 2) - (rto >> 1))
1255 fin_timeout = (rto << 2) - (rto >> 1);
1256
1257 return fin_timeout;
1258}
1259
1260static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1261 int paws_win)
1262{
1263 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1264 return true;
1265 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1266 return true;
1267 /*
1268 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1269 * then following tcp messages have valid values. Ignore 0 value,
1270 * or else 'negative' tsval might forbid us to accept their packets.
1271 */
1272 if (!rx_opt->ts_recent)
1273 return true;
1274 return false;
1275}
1276
1277static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1278 int rst)
1279{
1280 if (tcp_paws_check(rx_opt, 0))
1281 return false;
1282
1283 /* RST segments are not recommended to carry timestamp,
1284 and, if they do, it is recommended to ignore PAWS because
1285 "their cleanup function should take precedence over timestamps."
1286 Certainly, it is mistake. It is necessary to understand the reasons
1287 of this constraint to relax it: if peer reboots, clock may go
1288 out-of-sync and half-open connections will not be reset.
1289 Actually, the problem would be not existing if all
1290 the implementations followed draft about maintaining clock
1291 via reboots. Linux-2.2 DOES NOT!
1292
1293 However, we can relax time bounds for RST segments to MSL.
1294 */
1295 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1296 return false;
1297 return true;
1298}
1299
1300bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1301 int mib_idx, u32 *last_oow_ack_time);
1302
1303static inline void tcp_mib_init(struct net *net)
1304{
1305 /* See RFC 2012 */
1306 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1307 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1308 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1309 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1310}
1311
1312/* from STCP */
1313static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1314{
1315 tp->lost_skb_hint = NULL;
1316}
1317
1318static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1319{
1320 tcp_clear_retrans_hints_partial(tp);
1321 tp->retransmit_skb_hint = NULL;
1322}
1323
1324union tcp_md5_addr {
1325 struct in_addr a4;
1326#if IS_ENABLED(CONFIG_IPV6)
1327 struct in6_addr a6;
1328#endif
1329};
1330
1331/* - key database */
1332struct tcp_md5sig_key {
1333 struct hlist_node node;
1334 u8 keylen;
1335 u8 family; /* AF_INET or AF_INET6 */
1336 union tcp_md5_addr addr;
1337 u8 key[TCP_MD5SIG_MAXKEYLEN];
1338 struct rcu_head rcu;
1339};
1340
1341/* - sock block */
1342struct tcp_md5sig_info {
1343 struct hlist_head head;
1344 struct rcu_head rcu;
1345};
1346
1347/* - pseudo header */
1348struct tcp4_pseudohdr {
1349 __be32 saddr;
1350 __be32 daddr;
1351 __u8 pad;
1352 __u8 protocol;
1353 __be16 len;
1354};
1355
1356struct tcp6_pseudohdr {
1357 struct in6_addr saddr;
1358 struct in6_addr daddr;
1359 __be32 len;
1360 __be32 protocol; /* including padding */
1361};
1362
1363union tcp_md5sum_block {
1364 struct tcp4_pseudohdr ip4;
1365#if IS_ENABLED(CONFIG_IPV6)
1366 struct tcp6_pseudohdr ip6;
1367#endif
1368};
1369
1370/* - pool: digest algorithm, hash description and scratch buffer */
1371struct tcp_md5sig_pool {
1372 struct ahash_request *md5_req;
1373 union tcp_md5sum_block md5_blk;
1374};
1375
1376/* - functions */
1377int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1378 const struct sock *sk, const struct sk_buff *skb);
1379int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1380 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1381int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1382 int family);
1383struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1384 const struct sock *addr_sk);
1385
1386#ifdef CONFIG_TCP_MD5SIG
1387struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1388 const union tcp_md5_addr *addr,
1389 int family);
1390#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1391#else
1392static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1393 const union tcp_md5_addr *addr,
1394 int family)
1395{
1396 return NULL;
1397}
1398#define tcp_twsk_md5_key(twsk) NULL
1399#endif
1400
1401bool tcp_alloc_md5sig_pool(void);
1402
1403struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1404static inline void tcp_put_md5sig_pool(void)
1405{
1406 local_bh_enable();
1407}
1408
1409int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1410int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1411 unsigned int header_len);
1412int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1413 const struct tcp_md5sig_key *key);
1414
1415/* From tcp_fastopen.c */
1416void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1417 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1418 unsigned long *last_syn_loss);
1419void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1420 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1421 u16 try_exp);
1422struct tcp_fastopen_request {
1423 /* Fast Open cookie. Size 0 means a cookie request */
1424 struct tcp_fastopen_cookie cookie;
1425 struct msghdr *data; /* data in MSG_FASTOPEN */
1426 size_t size;
1427 int copied; /* queued in tcp_connect() */
1428};
1429void tcp_free_fastopen_req(struct tcp_sock *tp);
1430
1431extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1432int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1433void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1434struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1435 struct request_sock *req,
1436 struct tcp_fastopen_cookie *foc,
1437 struct dst_entry *dst);
1438void tcp_fastopen_init_key_once(bool publish);
1439#define TCP_FASTOPEN_KEY_LENGTH 16
1440
1441/* Fastopen key context */
1442struct tcp_fastopen_context {
1443 struct crypto_cipher *tfm;
1444 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1445 struct rcu_head rcu;
1446};
1447
1448/* write queue abstraction */
1449static inline void tcp_write_queue_purge(struct sock *sk)
1450{
1451 struct sk_buff *skb;
1452
1453 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1454 sk_wmem_free_skb(sk, skb);
1455 sk_mem_reclaim(sk);
1456 tcp_clear_all_retrans_hints(tcp_sk(sk));
1457}
1458
1459static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1460{
1461 return skb_peek(&sk->sk_write_queue);
1462}
1463
1464static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1465{
1466 return skb_peek_tail(&sk->sk_write_queue);
1467}
1468
1469static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1470 const struct sk_buff *skb)
1471{
1472 return skb_queue_next(&sk->sk_write_queue, skb);
1473}
1474
1475static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1476 const struct sk_buff *skb)
1477{
1478 return skb_queue_prev(&sk->sk_write_queue, skb);
1479}
1480
1481#define tcp_for_write_queue(skb, sk) \
1482 skb_queue_walk(&(sk)->sk_write_queue, skb)
1483
1484#define tcp_for_write_queue_from(skb, sk) \
1485 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1486
1487#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1488 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1489
1490static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1491{
1492 return sk->sk_send_head;
1493}
1494
1495static inline bool tcp_skb_is_last(const struct sock *sk,
1496 const struct sk_buff *skb)
1497{
1498 return skb_queue_is_last(&sk->sk_write_queue, skb);
1499}
1500
1501static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1502{
1503 if (tcp_skb_is_last(sk, skb))
1504 sk->sk_send_head = NULL;
1505 else
1506 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1507}
1508
1509static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1510{
1511 if (sk->sk_send_head == skb_unlinked)
1512 sk->sk_send_head = NULL;
1513}
1514
1515static inline void tcp_init_send_head(struct sock *sk)
1516{
1517 sk->sk_send_head = NULL;
1518}
1519
1520static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1521{
1522 __skb_queue_tail(&sk->sk_write_queue, skb);
1523}
1524
1525static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1526{
1527 __tcp_add_write_queue_tail(sk, skb);
1528
1529 /* Queue it, remembering where we must start sending. */
1530 if (sk->sk_send_head == NULL) {
1531 sk->sk_send_head = skb;
1532
1533 if (tcp_sk(sk)->highest_sack == NULL)
1534 tcp_sk(sk)->highest_sack = skb;
1535 }
1536}
1537
1538static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1539{
1540 __skb_queue_head(&sk->sk_write_queue, skb);
1541}
1542
1543/* Insert buff after skb on the write queue of sk. */
1544static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1545 struct sk_buff *buff,
1546 struct sock *sk)
1547{
1548 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1549}
1550
1551/* Insert new before skb on the write queue of sk. */
1552static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1553 struct sk_buff *skb,
1554 struct sock *sk)
1555{
1556 __skb_queue_before(&sk->sk_write_queue, skb, new);
1557
1558 if (sk->sk_send_head == skb)
1559 sk->sk_send_head = new;
1560}
1561
1562static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1563{
1564 __skb_unlink(skb, &sk->sk_write_queue);
1565}
1566
1567static inline bool tcp_write_queue_empty(struct sock *sk)
1568{
1569 return skb_queue_empty(&sk->sk_write_queue);
1570}
1571
1572static inline void tcp_push_pending_frames(struct sock *sk)
1573{
1574 if (tcp_send_head(sk)) {
1575 struct tcp_sock *tp = tcp_sk(sk);
1576
1577 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1578 }
1579}
1580
1581/* Start sequence of the skb just after the highest skb with SACKed
1582 * bit, valid only if sacked_out > 0 or when the caller has ensured
1583 * validity by itself.
1584 */
1585static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1586{
1587 if (!tp->sacked_out)
1588 return tp->snd_una;
1589
1590 if (tp->highest_sack == NULL)
1591 return tp->snd_nxt;
1592
1593 return TCP_SKB_CB(tp->highest_sack)->seq;
1594}
1595
1596static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1597{
1598 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1599 tcp_write_queue_next(sk, skb);
1600}
1601
1602static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1603{
1604 return tcp_sk(sk)->highest_sack;
1605}
1606
1607static inline void tcp_highest_sack_reset(struct sock *sk)
1608{
1609 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1610}
1611
1612/* Called when old skb is about to be deleted (to be combined with new skb) */
1613static inline void tcp_highest_sack_combine(struct sock *sk,
1614 struct sk_buff *old,
1615 struct sk_buff *new)
1616{
1617 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1618 tcp_sk(sk)->highest_sack = new;
1619}
1620
1621/* This helper checks if socket has IP_TRANSPARENT set */
1622static inline bool inet_sk_transparent(const struct sock *sk)
1623{
1624 switch (sk->sk_state) {
1625 case TCP_TIME_WAIT:
1626 return inet_twsk(sk)->tw_transparent;
1627 case TCP_NEW_SYN_RECV:
1628 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1629 }
1630 return inet_sk(sk)->transparent;
1631}
1632
1633/* Determines whether this is a thin stream (which may suffer from
1634 * increased latency). Used to trigger latency-reducing mechanisms.
1635 */
1636static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1637{
1638 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1639}
1640
1641/* /proc */
1642enum tcp_seq_states {
1643 TCP_SEQ_STATE_LISTENING,
1644 TCP_SEQ_STATE_ESTABLISHED,
1645};
1646
1647int tcp_seq_open(struct inode *inode, struct file *file);
1648
1649struct tcp_seq_afinfo {
1650 char *name;
1651 sa_family_t family;
1652 const struct file_operations *seq_fops;
1653 struct seq_operations seq_ops;
1654};
1655
1656struct tcp_iter_state {
1657 struct seq_net_private p;
1658 sa_family_t family;
1659 enum tcp_seq_states state;
1660 struct sock *syn_wait_sk;
1661 int bucket, offset, sbucket, num;
1662 loff_t last_pos;
1663};
1664
1665int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1666void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1667
1668extern struct request_sock_ops tcp_request_sock_ops;
1669extern struct request_sock_ops tcp6_request_sock_ops;
1670
1671void tcp_v4_destroy_sock(struct sock *sk);
1672
1673struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1674 netdev_features_t features);
1675struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1676int tcp_gro_complete(struct sk_buff *skb);
1677
1678void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1679
1680static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1681{
1682 struct net *net = sock_net((struct sock *)tp);
1683 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1684}
1685
1686static inline bool tcp_stream_memory_free(const struct sock *sk)
1687{
1688 const struct tcp_sock *tp = tcp_sk(sk);
1689 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1690
1691 return notsent_bytes < tcp_notsent_lowat(tp);
1692}
1693
1694#ifdef CONFIG_PROC_FS
1695int tcp4_proc_init(void);
1696void tcp4_proc_exit(void);
1697#endif
1698
1699int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1700int tcp_conn_request(struct request_sock_ops *rsk_ops,
1701 const struct tcp_request_sock_ops *af_ops,
1702 struct sock *sk, struct sk_buff *skb);
1703
1704/* TCP af-specific functions */
1705struct tcp_sock_af_ops {
1706#ifdef CONFIG_TCP_MD5SIG
1707 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1708 const struct sock *addr_sk);
1709 int (*calc_md5_hash)(char *location,
1710 const struct tcp_md5sig_key *md5,
1711 const struct sock *sk,
1712 const struct sk_buff *skb);
1713 int (*md5_parse)(struct sock *sk,
1714 char __user *optval,
1715 int optlen);
1716#endif
1717};
1718
1719struct tcp_request_sock_ops {
1720 u16 mss_clamp;
1721#ifdef CONFIG_TCP_MD5SIG
1722 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1723 const struct sock *addr_sk);
1724 int (*calc_md5_hash) (char *location,
1725 const struct tcp_md5sig_key *md5,
1726 const struct sock *sk,
1727 const struct sk_buff *skb);
1728#endif
1729 void (*init_req)(struct request_sock *req,
1730 const struct sock *sk_listener,
1731 struct sk_buff *skb);
1732#ifdef CONFIG_SYN_COOKIES
1733 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1734 __u16 *mss);
1735#endif
1736 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1737 const struct request_sock *req,
1738 bool *strict);
1739 __u32 (*init_seq)(const struct sk_buff *skb);
1740 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1741 struct flowi *fl, struct request_sock *req,
1742 struct tcp_fastopen_cookie *foc,
1743 bool attach_req);
1744};
1745
1746#ifdef CONFIG_SYN_COOKIES
1747static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1748 const struct sock *sk, struct sk_buff *skb,
1749 __u16 *mss)
1750{
1751 tcp_synq_overflow(sk);
1752 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1753 return ops->cookie_init_seq(skb, mss);
1754}
1755#else
1756static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1757 const struct sock *sk, struct sk_buff *skb,
1758 __u16 *mss)
1759{
1760 return 0;
1761}
1762#endif
1763
1764int tcpv4_offload_init(void);
1765
1766void tcp_v4_init(void);
1767void tcp_init(void);
1768
1769/* tcp_recovery.c */
1770
1771/* Flags to enable various loss recovery features. See below */
1772extern int sysctl_tcp_recovery;
1773
1774/* Use TCP RACK to detect (some) tail and retransmit losses */
1775#define TCP_RACK_LOST_RETRANS 0x1
1776
1777extern int tcp_rack_mark_lost(struct sock *sk);
1778
1779extern void tcp_rack_advance(struct tcp_sock *tp,
1780 const struct skb_mstamp *xmit_time, u8 sacked);
1781
1782/*
1783 * Save and compile IPv4 options, return a pointer to it
1784 */
1785static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
1786{
1787 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1788 struct ip_options_rcu *dopt = NULL;
1789
1790 if (opt->optlen) {
1791 int opt_size = sizeof(*dopt) + opt->optlen;
1792
1793 dopt = kmalloc(opt_size, GFP_ATOMIC);
1794 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
1795 kfree(dopt);
1796 dopt = NULL;
1797 }
1798 }
1799 return dopt;
1800}
1801
1802/* locally generated TCP pure ACKs have skb->truesize == 2
1803 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1804 * This is much faster than dissecting the packet to find out.
1805 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1806 */
1807static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1808{
1809 return skb->truesize == 2;
1810}
1811
1812static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1813{
1814 skb->truesize = 2;
1815}
1816
1817static inline int tcp_inq(struct sock *sk)
1818{
1819 struct tcp_sock *tp = tcp_sk(sk);
1820 int answ;
1821
1822 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1823 answ = 0;
1824 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1825 !tp->urg_data ||
1826 before(tp->urg_seq, tp->copied_seq) ||
1827 !before(tp->urg_seq, tp->rcv_nxt)) {
1828
1829 answ = tp->rcv_nxt - tp->copied_seq;
1830
1831 /* Subtract 1, if FIN was received */
1832 if (answ && sock_flag(sk, SOCK_DONE))
1833 answ--;
1834 } else {
1835 answ = tp->urg_seq - tp->copied_seq;
1836 }
1837
1838 return answ;
1839}
1840
1841static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1842{
1843 u16 segs_in;
1844
1845 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1846 tp->segs_in += segs_in;
1847 if (skb->len > tcp_hdrlen(skb))
1848 tp->data_segs_in += segs_in;
1849}
1850
1851#endif /* _TCP_H */