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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/dmaengine.h>
31#include <linux/crypto.h>
32#include <linux/cryptohash.h>
33#include <linux/kref.h>
34
35#include <net/inet_connection_sock.h>
36#include <net/inet_timewait_sock.h>
37#include <net/inet_hashtables.h>
38#include <net/checksum.h>
39#include <net/request_sock.h>
40#include <net/sock.h>
41#include <net/snmp.h>
42#include <net/ip.h>
43#include <net/tcp_states.h>
44#include <net/inet_ecn.h>
45#include <net/dst.h>
46
47#include <linux/seq_file.h>
48#include <linux/memcontrol.h>
49
50extern struct inet_hashinfo tcp_hashinfo;
51
52extern struct percpu_counter tcp_orphan_count;
53extern void tcp_time_wait(struct sock *sk, int state, int timeo);
54
55#define MAX_TCP_HEADER (128 + MAX_HEADER)
56#define MAX_TCP_OPTION_SPACE 40
57
58/*
59 * Never offer a window over 32767 without using window scaling. Some
60 * poor stacks do signed 16bit maths!
61 */
62#define MAX_TCP_WINDOW 32767U
63
64/* Offer an initial receive window of 10 mss. */
65#define TCP_DEFAULT_INIT_RCVWND 10
66
67/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68#define TCP_MIN_MSS 88U
69
70/* The least MTU to use for probing */
71#define TCP_BASE_MSS 512
72
73/* After receiving this amount of duplicate ACKs fast retransmit starts. */
74#define TCP_FASTRETRANS_THRESH 3
75
76/* Maximal reordering. */
77#define TCP_MAX_REORDERING 127
78
79/* Maximal number of ACKs sent quickly to accelerate slow-start. */
80#define TCP_MAX_QUICKACKS 16U
81
82/* urg_data states */
83#define TCP_URG_VALID 0x0100
84#define TCP_URG_NOTYET 0x0200
85#define TCP_URG_READ 0x0400
86
87#define TCP_RETR1 3 /*
88 * This is how many retries it does before it
89 * tries to figure out if the gateway is
90 * down. Minimal RFC value is 3; it corresponds
91 * to ~3sec-8min depending on RTO.
92 */
93
94#define TCP_RETR2 15 /*
95 * This should take at least
96 * 90 minutes to time out.
97 * RFC1122 says that the limit is 100 sec.
98 * 15 is ~13-30min depending on RTO.
99 */
100
101#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
102 * connection: ~180sec is RFC minimum */
103
104#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
105 * connection: ~180sec is RFC minimum */
106
107#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
108 * state, about 60 seconds */
109#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
110 /* BSD style FIN_WAIT2 deadlock breaker.
111 * It used to be 3min, new value is 60sec,
112 * to combine FIN-WAIT-2 timeout with
113 * TIME-WAIT timer.
114 */
115
116#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
117#if HZ >= 100
118#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
119#define TCP_ATO_MIN ((unsigned)(HZ/25))
120#else
121#define TCP_DELACK_MIN 4U
122#define TCP_ATO_MIN 4U
123#endif
124#define TCP_RTO_MAX ((unsigned)(120*HZ))
125#define TCP_RTO_MIN ((unsigned)(HZ/5))
126#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
127#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
128 * used as a fallback RTO for the
129 * initial data transmission if no
130 * valid RTT sample has been acquired,
131 * most likely due to retrans in 3WHS.
132 */
133
134#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
135 * for local resources.
136 */
137
138#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
139#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
140#define TCP_KEEPALIVE_INTVL (75*HZ)
141
142#define MAX_TCP_KEEPIDLE 32767
143#define MAX_TCP_KEEPINTVL 32767
144#define MAX_TCP_KEEPCNT 127
145#define MAX_TCP_SYNCNT 127
146
147#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
148
149#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
150#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
151 * after this time. It should be equal
152 * (or greater than) TCP_TIMEWAIT_LEN
153 * to provide reliability equal to one
154 * provided by timewait state.
155 */
156#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
157 * timestamps. It must be less than
158 * minimal timewait lifetime.
159 */
160/*
161 * TCP option
162 */
163
164#define TCPOPT_NOP 1 /* Padding */
165#define TCPOPT_EOL 0 /* End of options */
166#define TCPOPT_MSS 2 /* Segment size negotiating */
167#define TCPOPT_WINDOW 3 /* Window scaling */
168#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
169#define TCPOPT_SACK 5 /* SACK Block */
170#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
171#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
172#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
173
174/*
175 * TCP option lengths
176 */
177
178#define TCPOLEN_MSS 4
179#define TCPOLEN_WINDOW 3
180#define TCPOLEN_SACK_PERM 2
181#define TCPOLEN_TIMESTAMP 10
182#define TCPOLEN_MD5SIG 18
183#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
184#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
185#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
186#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
187
188/* But this is what stacks really send out. */
189#define TCPOLEN_TSTAMP_ALIGNED 12
190#define TCPOLEN_WSCALE_ALIGNED 4
191#define TCPOLEN_SACKPERM_ALIGNED 4
192#define TCPOLEN_SACK_BASE 2
193#define TCPOLEN_SACK_BASE_ALIGNED 4
194#define TCPOLEN_SACK_PERBLOCK 8
195#define TCPOLEN_MD5SIG_ALIGNED 20
196#define TCPOLEN_MSS_ALIGNED 4
197
198/* Flags in tp->nonagle */
199#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
200#define TCP_NAGLE_CORK 2 /* Socket is corked */
201#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
202
203/* TCP thin-stream limits */
204#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
205
206/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
207#define TCP_INIT_CWND 10
208
209extern struct inet_timewait_death_row tcp_death_row;
210
211/* sysctl variables for tcp */
212extern int sysctl_tcp_timestamps;
213extern int sysctl_tcp_window_scaling;
214extern int sysctl_tcp_sack;
215extern int sysctl_tcp_fin_timeout;
216extern int sysctl_tcp_keepalive_time;
217extern int sysctl_tcp_keepalive_probes;
218extern int sysctl_tcp_keepalive_intvl;
219extern int sysctl_tcp_syn_retries;
220extern int sysctl_tcp_synack_retries;
221extern int sysctl_tcp_retries1;
222extern int sysctl_tcp_retries2;
223extern int sysctl_tcp_orphan_retries;
224extern int sysctl_tcp_syncookies;
225extern int sysctl_tcp_retrans_collapse;
226extern int sysctl_tcp_stdurg;
227extern int sysctl_tcp_rfc1337;
228extern int sysctl_tcp_abort_on_overflow;
229extern int sysctl_tcp_max_orphans;
230extern int sysctl_tcp_fack;
231extern int sysctl_tcp_reordering;
232extern int sysctl_tcp_ecn;
233extern int sysctl_tcp_dsack;
234extern int sysctl_tcp_wmem[3];
235extern int sysctl_tcp_rmem[3];
236extern int sysctl_tcp_app_win;
237extern int sysctl_tcp_adv_win_scale;
238extern int sysctl_tcp_tw_reuse;
239extern int sysctl_tcp_frto;
240extern int sysctl_tcp_frto_response;
241extern int sysctl_tcp_low_latency;
242extern int sysctl_tcp_dma_copybreak;
243extern int sysctl_tcp_nometrics_save;
244extern int sysctl_tcp_moderate_rcvbuf;
245extern int sysctl_tcp_tso_win_divisor;
246extern int sysctl_tcp_abc;
247extern int sysctl_tcp_mtu_probing;
248extern int sysctl_tcp_base_mss;
249extern int sysctl_tcp_workaround_signed_windows;
250extern int sysctl_tcp_slow_start_after_idle;
251extern int sysctl_tcp_max_ssthresh;
252extern int sysctl_tcp_cookie_size;
253extern int sysctl_tcp_thin_linear_timeouts;
254extern int sysctl_tcp_thin_dupack;
255extern int sysctl_tcp_early_retrans;
256
257extern atomic_long_t tcp_memory_allocated;
258extern struct percpu_counter tcp_sockets_allocated;
259extern int tcp_memory_pressure;
260
261/*
262 * The next routines deal with comparing 32 bit unsigned ints
263 * and worry about wraparound (automatic with unsigned arithmetic).
264 */
265
266static inline bool before(__u32 seq1, __u32 seq2)
267{
268 return (__s32)(seq1-seq2) < 0;
269}
270#define after(seq2, seq1) before(seq1, seq2)
271
272/* is s2<=s1<=s3 ? */
273static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
274{
275 return seq3 - seq2 >= seq1 - seq2;
276}
277
278static inline bool tcp_out_of_memory(struct sock *sk)
279{
280 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
281 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
282 return true;
283 return false;
284}
285
286static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
287{
288 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
289 int orphans = percpu_counter_read_positive(ocp);
290
291 if (orphans << shift > sysctl_tcp_max_orphans) {
292 orphans = percpu_counter_sum_positive(ocp);
293 if (orphans << shift > sysctl_tcp_max_orphans)
294 return true;
295 }
296 return false;
297}
298
299extern bool tcp_check_oom(struct sock *sk, int shift);
300
301/* syncookies: remember time of last synqueue overflow */
302static inline void tcp_synq_overflow(struct sock *sk)
303{
304 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
305}
306
307/* syncookies: no recent synqueue overflow on this listening socket? */
308static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
309{
310 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
311 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
312}
313
314extern struct proto tcp_prot;
315
316#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
317#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
318#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
319#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
320#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
321
322extern void tcp_init_mem(struct net *net);
323
324extern void tcp_v4_err(struct sk_buff *skb, u32);
325
326extern void tcp_shutdown (struct sock *sk, int how);
327
328extern int tcp_v4_rcv(struct sk_buff *skb);
329
330extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
331extern void *tcp_v4_tw_get_peer(struct sock *sk);
332extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
333extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
334 size_t size);
335extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
336 size_t size, int flags);
337extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
338extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
339 const struct tcphdr *th, unsigned int len);
340extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
341 const struct tcphdr *th, unsigned int len);
342extern void tcp_rcv_space_adjust(struct sock *sk);
343extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
344extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
345extern void tcp_twsk_destructor(struct sock *sk);
346extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
347 struct pipe_inode_info *pipe, size_t len,
348 unsigned int flags);
349
350static inline void tcp_dec_quickack_mode(struct sock *sk,
351 const unsigned int pkts)
352{
353 struct inet_connection_sock *icsk = inet_csk(sk);
354
355 if (icsk->icsk_ack.quick) {
356 if (pkts >= icsk->icsk_ack.quick) {
357 icsk->icsk_ack.quick = 0;
358 /* Leaving quickack mode we deflate ATO. */
359 icsk->icsk_ack.ato = TCP_ATO_MIN;
360 } else
361 icsk->icsk_ack.quick -= pkts;
362 }
363}
364
365#define TCP_ECN_OK 1
366#define TCP_ECN_QUEUE_CWR 2
367#define TCP_ECN_DEMAND_CWR 4
368#define TCP_ECN_SEEN 8
369
370enum tcp_tw_status {
371 TCP_TW_SUCCESS = 0,
372 TCP_TW_RST = 1,
373 TCP_TW_ACK = 2,
374 TCP_TW_SYN = 3
375};
376
377
378extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
379 struct sk_buff *skb,
380 const struct tcphdr *th);
381extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
382 struct request_sock *req,
383 struct request_sock **prev);
384extern int tcp_child_process(struct sock *parent, struct sock *child,
385 struct sk_buff *skb);
386extern bool tcp_use_frto(struct sock *sk);
387extern void tcp_enter_frto(struct sock *sk);
388extern void tcp_enter_loss(struct sock *sk, int how);
389extern void tcp_clear_retrans(struct tcp_sock *tp);
390extern void tcp_update_metrics(struct sock *sk);
391extern void tcp_close(struct sock *sk, long timeout);
392extern void tcp_init_sock(struct sock *sk);
393extern unsigned int tcp_poll(struct file * file, struct socket *sock,
394 struct poll_table_struct *wait);
395extern int tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397extern int tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
400 char __user *optval, int __user *optlen);
401extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
402 char __user *optval, unsigned int optlen);
403extern void tcp_set_keepalive(struct sock *sk, int val);
404extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
405extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
406 size_t len, int nonblock, int flags, int *addr_len);
407extern void tcp_parse_options(const struct sk_buff *skb,
408 struct tcp_options_received *opt_rx, const u8 **hvpp,
409 int estab);
410extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
411
412/*
413 * TCP v4 functions exported for the inet6 API
414 */
415
416extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
417extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
418extern struct sock * tcp_create_openreq_child(struct sock *sk,
419 struct request_sock *req,
420 struct sk_buff *skb);
421extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
422 struct request_sock *req,
423 struct dst_entry *dst);
424extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
425extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
426 int addr_len);
427extern int tcp_connect(struct sock *sk);
428extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
429 struct request_sock *req,
430 struct request_values *rvp);
431extern int tcp_disconnect(struct sock *sk, int flags);
432
433void tcp_connect_init(struct sock *sk);
434void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
435int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
436
437/* From syncookies.c */
438extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
439extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
440 struct ip_options *opt);
441#ifdef CONFIG_SYN_COOKIES
442extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
443 __u16 *mss);
444#else
445static inline __u32 cookie_v4_init_sequence(struct sock *sk,
446 struct sk_buff *skb,
447 __u16 *mss)
448{
449 return 0;
450}
451#endif
452
453extern __u32 cookie_init_timestamp(struct request_sock *req);
454extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
455
456/* From net/ipv6/syncookies.c */
457extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
458#ifdef CONFIG_SYN_COOKIES
459extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
460 __u16 *mss);
461#else
462static inline __u32 cookie_v6_init_sequence(struct sock *sk,
463 struct sk_buff *skb,
464 __u16 *mss)
465{
466 return 0;
467}
468#endif
469/* tcp_output.c */
470
471extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
472 int nonagle);
473extern bool tcp_may_send_now(struct sock *sk);
474extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
475extern void tcp_retransmit_timer(struct sock *sk);
476extern void tcp_xmit_retransmit_queue(struct sock *);
477extern void tcp_simple_retransmit(struct sock *);
478extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
479extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
480
481extern void tcp_send_probe0(struct sock *);
482extern void tcp_send_partial(struct sock *);
483extern int tcp_write_wakeup(struct sock *);
484extern void tcp_send_fin(struct sock *sk);
485extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
486extern int tcp_send_synack(struct sock *);
487extern bool tcp_syn_flood_action(struct sock *sk,
488 const struct sk_buff *skb,
489 const char *proto);
490extern void tcp_push_one(struct sock *, unsigned int mss_now);
491extern void tcp_send_ack(struct sock *sk);
492extern void tcp_send_delayed_ack(struct sock *sk);
493
494/* tcp_input.c */
495extern void tcp_cwnd_application_limited(struct sock *sk);
496extern void tcp_resume_early_retransmit(struct sock *sk);
497extern void tcp_rearm_rto(struct sock *sk);
498
499/* tcp_timer.c */
500extern void tcp_init_xmit_timers(struct sock *);
501static inline void tcp_clear_xmit_timers(struct sock *sk)
502{
503 inet_csk_clear_xmit_timers(sk);
504}
505
506extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
507extern unsigned int tcp_current_mss(struct sock *sk);
508
509/* Bound MSS / TSO packet size with the half of the window */
510static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
511{
512 int cutoff;
513
514 /* When peer uses tiny windows, there is no use in packetizing
515 * to sub-MSS pieces for the sake of SWS or making sure there
516 * are enough packets in the pipe for fast recovery.
517 *
518 * On the other hand, for extremely large MSS devices, handling
519 * smaller than MSS windows in this way does make sense.
520 */
521 if (tp->max_window >= 512)
522 cutoff = (tp->max_window >> 1);
523 else
524 cutoff = tp->max_window;
525
526 if (cutoff && pktsize > cutoff)
527 return max_t(int, cutoff, 68U - tp->tcp_header_len);
528 else
529 return pktsize;
530}
531
532/* tcp.c */
533extern void tcp_get_info(const struct sock *, struct tcp_info *);
534
535/* Read 'sendfile()'-style from a TCP socket */
536typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
537 unsigned int, size_t);
538extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
539 sk_read_actor_t recv_actor);
540
541extern void tcp_initialize_rcv_mss(struct sock *sk);
542
543extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
544extern int tcp_mss_to_mtu(struct sock *sk, int mss);
545extern void tcp_mtup_init(struct sock *sk);
546extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
547
548static inline void tcp_bound_rto(const struct sock *sk)
549{
550 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
551 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
552}
553
554static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
555{
556 return (tp->srtt >> 3) + tp->rttvar;
557}
558
559static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
560{
561 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
562 ntohl(TCP_FLAG_ACK) |
563 snd_wnd);
564}
565
566static inline void tcp_fast_path_on(struct tcp_sock *tp)
567{
568 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
569}
570
571static inline void tcp_fast_path_check(struct sock *sk)
572{
573 struct tcp_sock *tp = tcp_sk(sk);
574
575 if (skb_queue_empty(&tp->out_of_order_queue) &&
576 tp->rcv_wnd &&
577 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
578 !tp->urg_data)
579 tcp_fast_path_on(tp);
580}
581
582/* Compute the actual rto_min value */
583static inline u32 tcp_rto_min(struct sock *sk)
584{
585 const struct dst_entry *dst = __sk_dst_get(sk);
586 u32 rto_min = TCP_RTO_MIN;
587
588 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
589 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
590 return rto_min;
591}
592
593/* Compute the actual receive window we are currently advertising.
594 * Rcv_nxt can be after the window if our peer push more data
595 * than the offered window.
596 */
597static inline u32 tcp_receive_window(const struct tcp_sock *tp)
598{
599 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
600
601 if (win < 0)
602 win = 0;
603 return (u32) win;
604}
605
606/* Choose a new window, without checks for shrinking, and without
607 * scaling applied to the result. The caller does these things
608 * if necessary. This is a "raw" window selection.
609 */
610extern u32 __tcp_select_window(struct sock *sk);
611
612void tcp_send_window_probe(struct sock *sk);
613
614/* TCP timestamps are only 32-bits, this causes a slight
615 * complication on 64-bit systems since we store a snapshot
616 * of jiffies in the buffer control blocks below. We decided
617 * to use only the low 32-bits of jiffies and hide the ugly
618 * casts with the following macro.
619 */
620#define tcp_time_stamp ((__u32)(jiffies))
621
622#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
623
624#define TCPHDR_FIN 0x01
625#define TCPHDR_SYN 0x02
626#define TCPHDR_RST 0x04
627#define TCPHDR_PSH 0x08
628#define TCPHDR_ACK 0x10
629#define TCPHDR_URG 0x20
630#define TCPHDR_ECE 0x40
631#define TCPHDR_CWR 0x80
632
633/* This is what the send packet queuing engine uses to pass
634 * TCP per-packet control information to the transmission code.
635 * We also store the host-order sequence numbers in here too.
636 * This is 44 bytes if IPV6 is enabled.
637 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
638 */
639struct tcp_skb_cb {
640 union {
641 struct inet_skb_parm h4;
642#if IS_ENABLED(CONFIG_IPV6)
643 struct inet6_skb_parm h6;
644#endif
645 } header; /* For incoming frames */
646 __u32 seq; /* Starting sequence number */
647 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
648 __u32 when; /* used to compute rtt's */
649 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
650
651 __u8 sacked; /* State flags for SACK/FACK. */
652#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
653#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
654#define TCPCB_LOST 0x04 /* SKB is lost */
655#define TCPCB_TAGBITS 0x07 /* All tag bits */
656#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
657#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
658
659 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
660 /* 1 byte hole */
661 __u32 ack_seq; /* Sequence number ACK'd */
662};
663
664#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
665
666/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
667 *
668 * If we receive a SYN packet with these bits set, it means a network is
669 * playing bad games with TOS bits. In order to avoid possible false congestion
670 * notifications, we disable TCP ECN negociation.
671 */
672static inline void
673TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb)
674{
675 const struct tcphdr *th = tcp_hdr(skb);
676
677 if (sysctl_tcp_ecn && th->ece && th->cwr &&
678 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
679 inet_rsk(req)->ecn_ok = 1;
680}
681
682/* Due to TSO, an SKB can be composed of multiple actual
683 * packets. To keep these tracked properly, we use this.
684 */
685static inline int tcp_skb_pcount(const struct sk_buff *skb)
686{
687 return skb_shinfo(skb)->gso_segs;
688}
689
690/* This is valid iff tcp_skb_pcount() > 1. */
691static inline int tcp_skb_mss(const struct sk_buff *skb)
692{
693 return skb_shinfo(skb)->gso_size;
694}
695
696/* Events passed to congestion control interface */
697enum tcp_ca_event {
698 CA_EVENT_TX_START, /* first transmit when no packets in flight */
699 CA_EVENT_CWND_RESTART, /* congestion window restart */
700 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
701 CA_EVENT_FRTO, /* fast recovery timeout */
702 CA_EVENT_LOSS, /* loss timeout */
703 CA_EVENT_FAST_ACK, /* in sequence ack */
704 CA_EVENT_SLOW_ACK, /* other ack */
705};
706
707/*
708 * Interface for adding new TCP congestion control handlers
709 */
710#define TCP_CA_NAME_MAX 16
711#define TCP_CA_MAX 128
712#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
713
714#define TCP_CONG_NON_RESTRICTED 0x1
715#define TCP_CONG_RTT_STAMP 0x2
716
717struct tcp_congestion_ops {
718 struct list_head list;
719 unsigned long flags;
720
721 /* initialize private data (optional) */
722 void (*init)(struct sock *sk);
723 /* cleanup private data (optional) */
724 void (*release)(struct sock *sk);
725
726 /* return slow start threshold (required) */
727 u32 (*ssthresh)(struct sock *sk);
728 /* lower bound for congestion window (optional) */
729 u32 (*min_cwnd)(const struct sock *sk);
730 /* do new cwnd calculation (required) */
731 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
732 /* call before changing ca_state (optional) */
733 void (*set_state)(struct sock *sk, u8 new_state);
734 /* call when cwnd event occurs (optional) */
735 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
736 /* new value of cwnd after loss (optional) */
737 u32 (*undo_cwnd)(struct sock *sk);
738 /* hook for packet ack accounting (optional) */
739 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
740 /* get info for inet_diag (optional) */
741 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
742
743 char name[TCP_CA_NAME_MAX];
744 struct module *owner;
745};
746
747extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
748extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
749
750extern void tcp_init_congestion_control(struct sock *sk);
751extern void tcp_cleanup_congestion_control(struct sock *sk);
752extern int tcp_set_default_congestion_control(const char *name);
753extern void tcp_get_default_congestion_control(char *name);
754extern void tcp_get_available_congestion_control(char *buf, size_t len);
755extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
756extern int tcp_set_allowed_congestion_control(char *allowed);
757extern int tcp_set_congestion_control(struct sock *sk, const char *name);
758extern void tcp_slow_start(struct tcp_sock *tp);
759extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
760
761extern struct tcp_congestion_ops tcp_init_congestion_ops;
762extern u32 tcp_reno_ssthresh(struct sock *sk);
763extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
764extern u32 tcp_reno_min_cwnd(const struct sock *sk);
765extern struct tcp_congestion_ops tcp_reno;
766
767static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
768{
769 struct inet_connection_sock *icsk = inet_csk(sk);
770
771 if (icsk->icsk_ca_ops->set_state)
772 icsk->icsk_ca_ops->set_state(sk, ca_state);
773 icsk->icsk_ca_state = ca_state;
774}
775
776static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
777{
778 const struct inet_connection_sock *icsk = inet_csk(sk);
779
780 if (icsk->icsk_ca_ops->cwnd_event)
781 icsk->icsk_ca_ops->cwnd_event(sk, event);
782}
783
784/* These functions determine how the current flow behaves in respect of SACK
785 * handling. SACK is negotiated with the peer, and therefore it can vary
786 * between different flows.
787 *
788 * tcp_is_sack - SACK enabled
789 * tcp_is_reno - No SACK
790 * tcp_is_fack - FACK enabled, implies SACK enabled
791 */
792static inline int tcp_is_sack(const struct tcp_sock *tp)
793{
794 return tp->rx_opt.sack_ok;
795}
796
797static inline bool tcp_is_reno(const struct tcp_sock *tp)
798{
799 return !tcp_is_sack(tp);
800}
801
802static inline bool tcp_is_fack(const struct tcp_sock *tp)
803{
804 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
805}
806
807static inline void tcp_enable_fack(struct tcp_sock *tp)
808{
809 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
810}
811
812/* TCP early-retransmit (ER) is similar to but more conservative than
813 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
814 */
815static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
816{
817 tp->do_early_retrans = sysctl_tcp_early_retrans &&
818 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3;
819 tp->early_retrans_delayed = 0;
820}
821
822static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
823{
824 tp->do_early_retrans = 0;
825}
826
827static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
828{
829 return tp->sacked_out + tp->lost_out;
830}
831
832/* This determines how many packets are "in the network" to the best
833 * of our knowledge. In many cases it is conservative, but where
834 * detailed information is available from the receiver (via SACK
835 * blocks etc.) we can make more aggressive calculations.
836 *
837 * Use this for decisions involving congestion control, use just
838 * tp->packets_out to determine if the send queue is empty or not.
839 *
840 * Read this equation as:
841 *
842 * "Packets sent once on transmission queue" MINUS
843 * "Packets left network, but not honestly ACKed yet" PLUS
844 * "Packets fast retransmitted"
845 */
846static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
847{
848 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
849}
850
851#define TCP_INFINITE_SSTHRESH 0x7fffffff
852
853static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
854{
855 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
856}
857
858/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
859 * The exception is rate halving phase, when cwnd is decreasing towards
860 * ssthresh.
861 */
862static inline __u32 tcp_current_ssthresh(const struct sock *sk)
863{
864 const struct tcp_sock *tp = tcp_sk(sk);
865
866 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
867 return tp->snd_ssthresh;
868 else
869 return max(tp->snd_ssthresh,
870 ((tp->snd_cwnd >> 1) +
871 (tp->snd_cwnd >> 2)));
872}
873
874/* Use define here intentionally to get WARN_ON location shown at the caller */
875#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
876
877extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
878extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
879
880/* The maximum number of MSS of available cwnd for which TSO defers
881 * sending if not using sysctl_tcp_tso_win_divisor.
882 */
883static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
884{
885 return 3;
886}
887
888/* Slow start with delack produces 3 packets of burst, so that
889 * it is safe "de facto". This will be the default - same as
890 * the default reordering threshold - but if reordering increases,
891 * we must be able to allow cwnd to burst at least this much in order
892 * to not pull it back when holes are filled.
893 */
894static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
895{
896 return tp->reordering;
897}
898
899/* Returns end sequence number of the receiver's advertised window */
900static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
901{
902 return tp->snd_una + tp->snd_wnd;
903}
904extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
905
906static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
907 const struct sk_buff *skb)
908{
909 if (skb->len < mss)
910 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
911}
912
913static inline void tcp_check_probe_timer(struct sock *sk)
914{
915 const struct tcp_sock *tp = tcp_sk(sk);
916 const struct inet_connection_sock *icsk = inet_csk(sk);
917
918 if (!tp->packets_out && !icsk->icsk_pending)
919 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
920 icsk->icsk_rto, TCP_RTO_MAX);
921}
922
923static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
924{
925 tp->snd_wl1 = seq;
926}
927
928static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
929{
930 tp->snd_wl1 = seq;
931}
932
933/*
934 * Calculate(/check) TCP checksum
935 */
936static inline __sum16 tcp_v4_check(int len, __be32 saddr,
937 __be32 daddr, __wsum base)
938{
939 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
940}
941
942static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
943{
944 return __skb_checksum_complete(skb);
945}
946
947static inline bool tcp_checksum_complete(struct sk_buff *skb)
948{
949 return !skb_csum_unnecessary(skb) &&
950 __tcp_checksum_complete(skb);
951}
952
953/* Prequeue for VJ style copy to user, combined with checksumming. */
954
955static inline void tcp_prequeue_init(struct tcp_sock *tp)
956{
957 tp->ucopy.task = NULL;
958 tp->ucopy.len = 0;
959 tp->ucopy.memory = 0;
960 skb_queue_head_init(&tp->ucopy.prequeue);
961#ifdef CONFIG_NET_DMA
962 tp->ucopy.dma_chan = NULL;
963 tp->ucopy.wakeup = 0;
964 tp->ucopy.pinned_list = NULL;
965 tp->ucopy.dma_cookie = 0;
966#endif
967}
968
969/* Packet is added to VJ-style prequeue for processing in process
970 * context, if a reader task is waiting. Apparently, this exciting
971 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
972 * failed somewhere. Latency? Burstiness? Well, at least now we will
973 * see, why it failed. 8)8) --ANK
974 *
975 * NOTE: is this not too big to inline?
976 */
977static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
978{
979 struct tcp_sock *tp = tcp_sk(sk);
980
981 if (sysctl_tcp_low_latency || !tp->ucopy.task)
982 return false;
983
984 __skb_queue_tail(&tp->ucopy.prequeue, skb);
985 tp->ucopy.memory += skb->truesize;
986 if (tp->ucopy.memory > sk->sk_rcvbuf) {
987 struct sk_buff *skb1;
988
989 BUG_ON(sock_owned_by_user(sk));
990
991 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
992 sk_backlog_rcv(sk, skb1);
993 NET_INC_STATS_BH(sock_net(sk),
994 LINUX_MIB_TCPPREQUEUEDROPPED);
995 }
996
997 tp->ucopy.memory = 0;
998 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
999 wake_up_interruptible_sync_poll(sk_sleep(sk),
1000 POLLIN | POLLRDNORM | POLLRDBAND);
1001 if (!inet_csk_ack_scheduled(sk))
1002 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1003 (3 * tcp_rto_min(sk)) / 4,
1004 TCP_RTO_MAX);
1005 }
1006 return true;
1007}
1008
1009
1010#undef STATE_TRACE
1011
1012#ifdef STATE_TRACE
1013static const char *statename[]={
1014 "Unused","Established","Syn Sent","Syn Recv",
1015 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1016 "Close Wait","Last ACK","Listen","Closing"
1017};
1018#endif
1019extern void tcp_set_state(struct sock *sk, int state);
1020
1021extern void tcp_done(struct sock *sk);
1022
1023static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1024{
1025 rx_opt->dsack = 0;
1026 rx_opt->num_sacks = 0;
1027}
1028
1029/* Determine a window scaling and initial window to offer. */
1030extern void tcp_select_initial_window(int __space, __u32 mss,
1031 __u32 *rcv_wnd, __u32 *window_clamp,
1032 int wscale_ok, __u8 *rcv_wscale,
1033 __u32 init_rcv_wnd);
1034
1035static inline int tcp_win_from_space(int space)
1036{
1037 return sysctl_tcp_adv_win_scale<=0 ?
1038 (space>>(-sysctl_tcp_adv_win_scale)) :
1039 space - (space>>sysctl_tcp_adv_win_scale);
1040}
1041
1042/* Note: caller must be prepared to deal with negative returns */
1043static inline int tcp_space(const struct sock *sk)
1044{
1045 return tcp_win_from_space(sk->sk_rcvbuf -
1046 atomic_read(&sk->sk_rmem_alloc));
1047}
1048
1049static inline int tcp_full_space(const struct sock *sk)
1050{
1051 return tcp_win_from_space(sk->sk_rcvbuf);
1052}
1053
1054static inline void tcp_openreq_init(struct request_sock *req,
1055 struct tcp_options_received *rx_opt,
1056 struct sk_buff *skb)
1057{
1058 struct inet_request_sock *ireq = inet_rsk(req);
1059
1060 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1061 req->cookie_ts = 0;
1062 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1063 req->mss = rx_opt->mss_clamp;
1064 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1065 ireq->tstamp_ok = rx_opt->tstamp_ok;
1066 ireq->sack_ok = rx_opt->sack_ok;
1067 ireq->snd_wscale = rx_opt->snd_wscale;
1068 ireq->wscale_ok = rx_opt->wscale_ok;
1069 ireq->acked = 0;
1070 ireq->ecn_ok = 0;
1071 ireq->rmt_port = tcp_hdr(skb)->source;
1072 ireq->loc_port = tcp_hdr(skb)->dest;
1073}
1074
1075extern void tcp_enter_memory_pressure(struct sock *sk);
1076
1077static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1078{
1079 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1080}
1081
1082static inline int keepalive_time_when(const struct tcp_sock *tp)
1083{
1084 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1085}
1086
1087static inline int keepalive_probes(const struct tcp_sock *tp)
1088{
1089 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1090}
1091
1092static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1093{
1094 const struct inet_connection_sock *icsk = &tp->inet_conn;
1095
1096 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1097 tcp_time_stamp - tp->rcv_tstamp);
1098}
1099
1100static inline int tcp_fin_time(const struct sock *sk)
1101{
1102 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1103 const int rto = inet_csk(sk)->icsk_rto;
1104
1105 if (fin_timeout < (rto << 2) - (rto >> 1))
1106 fin_timeout = (rto << 2) - (rto >> 1);
1107
1108 return fin_timeout;
1109}
1110
1111static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1112 int paws_win)
1113{
1114 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1115 return true;
1116 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1117 return true;
1118 /*
1119 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1120 * then following tcp messages have valid values. Ignore 0 value,
1121 * or else 'negative' tsval might forbid us to accept their packets.
1122 */
1123 if (!rx_opt->ts_recent)
1124 return true;
1125 return false;
1126}
1127
1128static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1129 int rst)
1130{
1131 if (tcp_paws_check(rx_opt, 0))
1132 return false;
1133
1134 /* RST segments are not recommended to carry timestamp,
1135 and, if they do, it is recommended to ignore PAWS because
1136 "their cleanup function should take precedence over timestamps."
1137 Certainly, it is mistake. It is necessary to understand the reasons
1138 of this constraint to relax it: if peer reboots, clock may go
1139 out-of-sync and half-open connections will not be reset.
1140 Actually, the problem would be not existing if all
1141 the implementations followed draft about maintaining clock
1142 via reboots. Linux-2.2 DOES NOT!
1143
1144 However, we can relax time bounds for RST segments to MSL.
1145 */
1146 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1147 return false;
1148 return true;
1149}
1150
1151static inline void tcp_mib_init(struct net *net)
1152{
1153 /* See RFC 2012 */
1154 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1155 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1156 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1157 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1158}
1159
1160/* from STCP */
1161static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1162{
1163 tp->lost_skb_hint = NULL;
1164 tp->scoreboard_skb_hint = NULL;
1165}
1166
1167static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1168{
1169 tcp_clear_retrans_hints_partial(tp);
1170 tp->retransmit_skb_hint = NULL;
1171}
1172
1173/* MD5 Signature */
1174struct crypto_hash;
1175
1176union tcp_md5_addr {
1177 struct in_addr a4;
1178#if IS_ENABLED(CONFIG_IPV6)
1179 struct in6_addr a6;
1180#endif
1181};
1182
1183/* - key database */
1184struct tcp_md5sig_key {
1185 struct hlist_node node;
1186 u8 keylen;
1187 u8 family; /* AF_INET or AF_INET6 */
1188 union tcp_md5_addr addr;
1189 u8 key[TCP_MD5SIG_MAXKEYLEN];
1190 struct rcu_head rcu;
1191};
1192
1193/* - sock block */
1194struct tcp_md5sig_info {
1195 struct hlist_head head;
1196 struct rcu_head rcu;
1197};
1198
1199/* - pseudo header */
1200struct tcp4_pseudohdr {
1201 __be32 saddr;
1202 __be32 daddr;
1203 __u8 pad;
1204 __u8 protocol;
1205 __be16 len;
1206};
1207
1208struct tcp6_pseudohdr {
1209 struct in6_addr saddr;
1210 struct in6_addr daddr;
1211 __be32 len;
1212 __be32 protocol; /* including padding */
1213};
1214
1215union tcp_md5sum_block {
1216 struct tcp4_pseudohdr ip4;
1217#if IS_ENABLED(CONFIG_IPV6)
1218 struct tcp6_pseudohdr ip6;
1219#endif
1220};
1221
1222/* - pool: digest algorithm, hash description and scratch buffer */
1223struct tcp_md5sig_pool {
1224 struct hash_desc md5_desc;
1225 union tcp_md5sum_block md5_blk;
1226};
1227
1228/* - functions */
1229extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1230 const struct sock *sk,
1231 const struct request_sock *req,
1232 const struct sk_buff *skb);
1233extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1234 int family, const u8 *newkey,
1235 u8 newkeylen, gfp_t gfp);
1236extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1237 int family);
1238extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1239 struct sock *addr_sk);
1240
1241#ifdef CONFIG_TCP_MD5SIG
1242extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1243 const union tcp_md5_addr *addr, int family);
1244#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1245#else
1246static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1247 const union tcp_md5_addr *addr,
1248 int family)
1249{
1250 return NULL;
1251}
1252#define tcp_twsk_md5_key(twsk) NULL
1253#endif
1254
1255extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1256extern void tcp_free_md5sig_pool(void);
1257
1258extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1259extern void tcp_put_md5sig_pool(void);
1260
1261extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1262extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1263 unsigned int header_len);
1264extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1265 const struct tcp_md5sig_key *key);
1266
1267/* write queue abstraction */
1268static inline void tcp_write_queue_purge(struct sock *sk)
1269{
1270 struct sk_buff *skb;
1271
1272 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1273 sk_wmem_free_skb(sk, skb);
1274 sk_mem_reclaim(sk);
1275 tcp_clear_all_retrans_hints(tcp_sk(sk));
1276}
1277
1278static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1279{
1280 return skb_peek(&sk->sk_write_queue);
1281}
1282
1283static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1284{
1285 return skb_peek_tail(&sk->sk_write_queue);
1286}
1287
1288static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1289 const struct sk_buff *skb)
1290{
1291 return skb_queue_next(&sk->sk_write_queue, skb);
1292}
1293
1294static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1295 const struct sk_buff *skb)
1296{
1297 return skb_queue_prev(&sk->sk_write_queue, skb);
1298}
1299
1300#define tcp_for_write_queue(skb, sk) \
1301 skb_queue_walk(&(sk)->sk_write_queue, skb)
1302
1303#define tcp_for_write_queue_from(skb, sk) \
1304 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1305
1306#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1307 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1308
1309static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1310{
1311 return sk->sk_send_head;
1312}
1313
1314static inline bool tcp_skb_is_last(const struct sock *sk,
1315 const struct sk_buff *skb)
1316{
1317 return skb_queue_is_last(&sk->sk_write_queue, skb);
1318}
1319
1320static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1321{
1322 if (tcp_skb_is_last(sk, skb))
1323 sk->sk_send_head = NULL;
1324 else
1325 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1326}
1327
1328static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1329{
1330 if (sk->sk_send_head == skb_unlinked)
1331 sk->sk_send_head = NULL;
1332}
1333
1334static inline void tcp_init_send_head(struct sock *sk)
1335{
1336 sk->sk_send_head = NULL;
1337}
1338
1339static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1340{
1341 __skb_queue_tail(&sk->sk_write_queue, skb);
1342}
1343
1344static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1345{
1346 __tcp_add_write_queue_tail(sk, skb);
1347
1348 /* Queue it, remembering where we must start sending. */
1349 if (sk->sk_send_head == NULL) {
1350 sk->sk_send_head = skb;
1351
1352 if (tcp_sk(sk)->highest_sack == NULL)
1353 tcp_sk(sk)->highest_sack = skb;
1354 }
1355}
1356
1357static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1358{
1359 __skb_queue_head(&sk->sk_write_queue, skb);
1360}
1361
1362/* Insert buff after skb on the write queue of sk. */
1363static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1364 struct sk_buff *buff,
1365 struct sock *sk)
1366{
1367 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1368}
1369
1370/* Insert new before skb on the write queue of sk. */
1371static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1372 struct sk_buff *skb,
1373 struct sock *sk)
1374{
1375 __skb_queue_before(&sk->sk_write_queue, skb, new);
1376
1377 if (sk->sk_send_head == skb)
1378 sk->sk_send_head = new;
1379}
1380
1381static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1382{
1383 __skb_unlink(skb, &sk->sk_write_queue);
1384}
1385
1386static inline bool tcp_write_queue_empty(struct sock *sk)
1387{
1388 return skb_queue_empty(&sk->sk_write_queue);
1389}
1390
1391static inline void tcp_push_pending_frames(struct sock *sk)
1392{
1393 if (tcp_send_head(sk)) {
1394 struct tcp_sock *tp = tcp_sk(sk);
1395
1396 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1397 }
1398}
1399
1400/* Start sequence of the skb just after the highest skb with SACKed
1401 * bit, valid only if sacked_out > 0 or when the caller has ensured
1402 * validity by itself.
1403 */
1404static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1405{
1406 if (!tp->sacked_out)
1407 return tp->snd_una;
1408
1409 if (tp->highest_sack == NULL)
1410 return tp->snd_nxt;
1411
1412 return TCP_SKB_CB(tp->highest_sack)->seq;
1413}
1414
1415static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1416{
1417 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1418 tcp_write_queue_next(sk, skb);
1419}
1420
1421static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1422{
1423 return tcp_sk(sk)->highest_sack;
1424}
1425
1426static inline void tcp_highest_sack_reset(struct sock *sk)
1427{
1428 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1429}
1430
1431/* Called when old skb is about to be deleted (to be combined with new skb) */
1432static inline void tcp_highest_sack_combine(struct sock *sk,
1433 struct sk_buff *old,
1434 struct sk_buff *new)
1435{
1436 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1437 tcp_sk(sk)->highest_sack = new;
1438}
1439
1440/* Determines whether this is a thin stream (which may suffer from
1441 * increased latency). Used to trigger latency-reducing mechanisms.
1442 */
1443static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1444{
1445 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1446}
1447
1448/* /proc */
1449enum tcp_seq_states {
1450 TCP_SEQ_STATE_LISTENING,
1451 TCP_SEQ_STATE_OPENREQ,
1452 TCP_SEQ_STATE_ESTABLISHED,
1453 TCP_SEQ_STATE_TIME_WAIT,
1454};
1455
1456int tcp_seq_open(struct inode *inode, struct file *file);
1457
1458struct tcp_seq_afinfo {
1459 char *name;
1460 sa_family_t family;
1461 const struct file_operations *seq_fops;
1462 struct seq_operations seq_ops;
1463};
1464
1465struct tcp_iter_state {
1466 struct seq_net_private p;
1467 sa_family_t family;
1468 enum tcp_seq_states state;
1469 struct sock *syn_wait_sk;
1470 int bucket, offset, sbucket, num, uid;
1471 loff_t last_pos;
1472};
1473
1474extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1475extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1476
1477extern struct request_sock_ops tcp_request_sock_ops;
1478extern struct request_sock_ops tcp6_request_sock_ops;
1479
1480extern void tcp_v4_destroy_sock(struct sock *sk);
1481
1482extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1483extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1484 netdev_features_t features);
1485extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1486 struct sk_buff *skb);
1487extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1488 struct sk_buff *skb);
1489extern int tcp_gro_complete(struct sk_buff *skb);
1490extern int tcp4_gro_complete(struct sk_buff *skb);
1491
1492#ifdef CONFIG_PROC_FS
1493extern int tcp4_proc_init(void);
1494extern void tcp4_proc_exit(void);
1495#endif
1496
1497/* TCP af-specific functions */
1498struct tcp_sock_af_ops {
1499#ifdef CONFIG_TCP_MD5SIG
1500 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1501 struct sock *addr_sk);
1502 int (*calc_md5_hash) (char *location,
1503 struct tcp_md5sig_key *md5,
1504 const struct sock *sk,
1505 const struct request_sock *req,
1506 const struct sk_buff *skb);
1507 int (*md5_parse) (struct sock *sk,
1508 char __user *optval,
1509 int optlen);
1510#endif
1511};
1512
1513struct tcp_request_sock_ops {
1514#ifdef CONFIG_TCP_MD5SIG
1515 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1516 struct request_sock *req);
1517 int (*calc_md5_hash) (char *location,
1518 struct tcp_md5sig_key *md5,
1519 const struct sock *sk,
1520 const struct request_sock *req,
1521 const struct sk_buff *skb);
1522#endif
1523};
1524
1525/* Using SHA1 for now, define some constants.
1526 */
1527#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1528#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1529#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1530
1531extern int tcp_cookie_generator(u32 *bakery);
1532
1533/**
1534 * struct tcp_cookie_values - each socket needs extra space for the
1535 * cookies, together with (optional) space for any SYN data.
1536 *
1537 * A tcp_sock contains a pointer to the current value, and this is
1538 * cloned to the tcp_timewait_sock.
1539 *
1540 * @cookie_pair: variable data from the option exchange.
1541 *
1542 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1543 * indicates default (sysctl_tcp_cookie_size).
1544 * After cookie sent, remembers size of cookie.
1545 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1546 *
1547 * @s_data_desired: user specified tcpct_s_data_desired. When the
1548 * constant payload is specified (@s_data_constant),
1549 * holds its length instead.
1550 * Range 0 to TCP_MSS_DESIRED.
1551 *
1552 * @s_data_payload: constant data that is to be included in the
1553 * payload of SYN or SYNACK segments when the
1554 * cookie option is present.
1555 */
1556struct tcp_cookie_values {
1557 struct kref kref;
1558 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1559 u8 cookie_pair_size;
1560 u8 cookie_desired;
1561 u16 s_data_desired:11,
1562 s_data_constant:1,
1563 s_data_in:1,
1564 s_data_out:1,
1565 s_data_unused:2;
1566 u8 s_data_payload[0];
1567};
1568
1569static inline void tcp_cookie_values_release(struct kref *kref)
1570{
1571 kfree(container_of(kref, struct tcp_cookie_values, kref));
1572}
1573
1574/* The length of constant payload data. Note that s_data_desired is
1575 * overloaded, depending on s_data_constant: either the length of constant
1576 * data (returned here) or the limit on variable data.
1577 */
1578static inline int tcp_s_data_size(const struct tcp_sock *tp)
1579{
1580 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1581 ? tp->cookie_values->s_data_desired
1582 : 0;
1583}
1584
1585/**
1586 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1587 *
1588 * As tcp_request_sock has already been extended in other places, the
1589 * only remaining method is to pass stack values along as function
1590 * parameters. These parameters are not needed after sending SYNACK.
1591 *
1592 * @cookie_bakery: cryptographic secret and message workspace.
1593 *
1594 * @cookie_plus: bytes in authenticator/cookie option, copied from
1595 * struct tcp_options_received (above).
1596 */
1597struct tcp_extend_values {
1598 struct request_values rv;
1599 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1600 u8 cookie_plus:6,
1601 cookie_out_never:1,
1602 cookie_in_always:1;
1603};
1604
1605static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1606{
1607 return (struct tcp_extend_values *)rvp;
1608}
1609
1610extern void tcp_v4_init(void);
1611extern void tcp_init(void);
1612
1613#endif /* _TCP_H */