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1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define TCP_DEBUG 1
22#define FASTRETRANS_DEBUG 1
23
24#include <linux/list.h>
25#include <linux/tcp.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
29#include <linux/skbuff.h>
30#include <linux/dmaengine.h>
31#include <linux/crypto.h>
32#include <linux/cryptohash.h>
33#include <linux/kref.h>
34
35#include <net/inet_connection_sock.h>
36#include <net/inet_timewait_sock.h>
37#include <net/inet_hashtables.h>
38#include <net/checksum.h>
39#include <net/request_sock.h>
40#include <net/sock.h>
41#include <net/snmp.h>
42#include <net/ip.h>
43#include <net/tcp_states.h>
44#include <net/inet_ecn.h>
45#include <net/dst.h>
46
47#include <linux/seq_file.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52extern void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER (128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56
57/*
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
60 */
61#define MAX_TCP_WINDOW 32767U
62
63/* Offer an initial receive window of 10 mss. */
64#define TCP_DEFAULT_INIT_RCVWND 10
65
66/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
67#define TCP_MIN_MSS 88U
68
69/* The least MTU to use for probing */
70#define TCP_BASE_MSS 512
71
72/* After receiving this amount of duplicate ACKs fast retransmit starts. */
73#define TCP_FASTRETRANS_THRESH 3
74
75/* Maximal reordering. */
76#define TCP_MAX_REORDERING 127
77
78/* Maximal number of ACKs sent quickly to accelerate slow-start. */
79#define TCP_MAX_QUICKACKS 16U
80
81/* urg_data states */
82#define TCP_URG_VALID 0x0100
83#define TCP_URG_NOTYET 0x0200
84#define TCP_URG_READ 0x0400
85
86#define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
91 */
92
93#define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
98 */
99
100#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
101 * connection: ~180sec is RFC minimum */
102
103#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
104 * connection: ~180sec is RFC minimum */
105
106#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
107 * state, about 60 seconds */
108#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
109 /* BSD style FIN_WAIT2 deadlock breaker.
110 * It used to be 3min, new value is 60sec,
111 * to combine FIN-WAIT-2 timeout with
112 * TIME-WAIT timer.
113 */
114
115#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
116#if HZ >= 100
117#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
118#define TCP_ATO_MIN ((unsigned)(HZ/25))
119#else
120#define TCP_DELACK_MIN 4U
121#define TCP_ATO_MIN 4U
122#endif
123#define TCP_RTO_MAX ((unsigned)(120*HZ))
124#define TCP_RTO_MIN ((unsigned)(HZ/5))
125#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC2988bis initial RTO value */
126#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
127 * used as a fallback RTO for the
128 * initial data transmission if no
129 * valid RTT sample has been acquired,
130 * most likely due to retrans in 3WHS.
131 */
132
133#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
134 * for local resources.
135 */
136
137#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
138#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
139#define TCP_KEEPALIVE_INTVL (75*HZ)
140
141#define MAX_TCP_KEEPIDLE 32767
142#define MAX_TCP_KEEPINTVL 32767
143#define MAX_TCP_KEEPCNT 127
144#define MAX_TCP_SYNCNT 127
145
146#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
147
148#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
149#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
150 * after this time. It should be equal
151 * (or greater than) TCP_TIMEWAIT_LEN
152 * to provide reliability equal to one
153 * provided by timewait state.
154 */
155#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
156 * timestamps. It must be less than
157 * minimal timewait lifetime.
158 */
159/*
160 * TCP option
161 */
162
163#define TCPOPT_NOP 1 /* Padding */
164#define TCPOPT_EOL 0 /* End of options */
165#define TCPOPT_MSS 2 /* Segment size negotiating */
166#define TCPOPT_WINDOW 3 /* Window scaling */
167#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
168#define TCPOPT_SACK 5 /* SACK Block */
169#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
170#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
171#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
172
173/*
174 * TCP option lengths
175 */
176
177#define TCPOLEN_MSS 4
178#define TCPOLEN_WINDOW 3
179#define TCPOLEN_SACK_PERM 2
180#define TCPOLEN_TIMESTAMP 10
181#define TCPOLEN_MD5SIG 18
182#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
183#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
184#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
185#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
186
187/* But this is what stacks really send out. */
188#define TCPOLEN_TSTAMP_ALIGNED 12
189#define TCPOLEN_WSCALE_ALIGNED 4
190#define TCPOLEN_SACKPERM_ALIGNED 4
191#define TCPOLEN_SACK_BASE 2
192#define TCPOLEN_SACK_BASE_ALIGNED 4
193#define TCPOLEN_SACK_PERBLOCK 8
194#define TCPOLEN_MD5SIG_ALIGNED 20
195#define TCPOLEN_MSS_ALIGNED 4
196
197/* Flags in tp->nonagle */
198#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
199#define TCP_NAGLE_CORK 2 /* Socket is corked */
200#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
201
202/* TCP thin-stream limits */
203#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
204
205/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
206#define TCP_INIT_CWND 10
207
208extern struct inet_timewait_death_row tcp_death_row;
209
210/* sysctl variables for tcp */
211extern int sysctl_tcp_timestamps;
212extern int sysctl_tcp_window_scaling;
213extern int sysctl_tcp_sack;
214extern int sysctl_tcp_fin_timeout;
215extern int sysctl_tcp_keepalive_time;
216extern int sysctl_tcp_keepalive_probes;
217extern int sysctl_tcp_keepalive_intvl;
218extern int sysctl_tcp_syn_retries;
219extern int sysctl_tcp_synack_retries;
220extern int sysctl_tcp_retries1;
221extern int sysctl_tcp_retries2;
222extern int sysctl_tcp_orphan_retries;
223extern int sysctl_tcp_syncookies;
224extern int sysctl_tcp_retrans_collapse;
225extern int sysctl_tcp_stdurg;
226extern int sysctl_tcp_rfc1337;
227extern int sysctl_tcp_abort_on_overflow;
228extern int sysctl_tcp_max_orphans;
229extern int sysctl_tcp_fack;
230extern int sysctl_tcp_reordering;
231extern int sysctl_tcp_ecn;
232extern int sysctl_tcp_dsack;
233extern long sysctl_tcp_mem[3];
234extern int sysctl_tcp_wmem[3];
235extern int sysctl_tcp_rmem[3];
236extern int sysctl_tcp_app_win;
237extern int sysctl_tcp_adv_win_scale;
238extern int sysctl_tcp_tw_reuse;
239extern int sysctl_tcp_frto;
240extern int sysctl_tcp_frto_response;
241extern int sysctl_tcp_low_latency;
242extern int sysctl_tcp_dma_copybreak;
243extern int sysctl_tcp_nometrics_save;
244extern int sysctl_tcp_moderate_rcvbuf;
245extern int sysctl_tcp_tso_win_divisor;
246extern int sysctl_tcp_abc;
247extern int sysctl_tcp_mtu_probing;
248extern int sysctl_tcp_base_mss;
249extern int sysctl_tcp_workaround_signed_windows;
250extern int sysctl_tcp_slow_start_after_idle;
251extern int sysctl_tcp_max_ssthresh;
252extern int sysctl_tcp_cookie_size;
253extern int sysctl_tcp_thin_linear_timeouts;
254extern int sysctl_tcp_thin_dupack;
255
256extern atomic_long_t tcp_memory_allocated;
257extern struct percpu_counter tcp_sockets_allocated;
258extern int tcp_memory_pressure;
259
260/*
261 * The next routines deal with comparing 32 bit unsigned ints
262 * and worry about wraparound (automatic with unsigned arithmetic).
263 */
264
265static inline int before(__u32 seq1, __u32 seq2)
266{
267 return (__s32)(seq1-seq2) < 0;
268}
269#define after(seq2, seq1) before(seq1, seq2)
270
271/* is s2<=s1<=s3 ? */
272static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
273{
274 return seq3 - seq2 >= seq1 - seq2;
275}
276
277static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
278{
279 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
280 int orphans = percpu_counter_read_positive(ocp);
281
282 if (orphans << shift > sysctl_tcp_max_orphans) {
283 orphans = percpu_counter_sum_positive(ocp);
284 if (orphans << shift > sysctl_tcp_max_orphans)
285 return true;
286 }
287
288 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
289 atomic_long_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])
290 return true;
291 return false;
292}
293
294/* syncookies: remember time of last synqueue overflow */
295static inline void tcp_synq_overflow(struct sock *sk)
296{
297 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
298}
299
300/* syncookies: no recent synqueue overflow on this listening socket? */
301static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
302{
303 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
304 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
305}
306
307extern struct proto tcp_prot;
308
309#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
311#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
312#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
313#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
314
315extern void tcp_v4_err(struct sk_buff *skb, u32);
316
317extern void tcp_shutdown (struct sock *sk, int how);
318
319extern int tcp_v4_rcv(struct sk_buff *skb);
320
321extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
322extern void *tcp_v4_tw_get_peer(struct sock *sk);
323extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
324extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
325 size_t size);
326extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
327 size_t size, int flags);
328extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
329extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
330 struct tcphdr *th, unsigned len);
331extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
332 struct tcphdr *th, unsigned len);
333extern void tcp_rcv_space_adjust(struct sock *sk);
334extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
335extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
336extern void tcp_twsk_destructor(struct sock *sk);
337extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
338 struct pipe_inode_info *pipe, size_t len,
339 unsigned int flags);
340
341static inline void tcp_dec_quickack_mode(struct sock *sk,
342 const unsigned int pkts)
343{
344 struct inet_connection_sock *icsk = inet_csk(sk);
345
346 if (icsk->icsk_ack.quick) {
347 if (pkts >= icsk->icsk_ack.quick) {
348 icsk->icsk_ack.quick = 0;
349 /* Leaving quickack mode we deflate ATO. */
350 icsk->icsk_ack.ato = TCP_ATO_MIN;
351 } else
352 icsk->icsk_ack.quick -= pkts;
353 }
354}
355
356#define TCP_ECN_OK 1
357#define TCP_ECN_QUEUE_CWR 2
358#define TCP_ECN_DEMAND_CWR 4
359
360static __inline__ void
361TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
362{
363 if (sysctl_tcp_ecn && th->ece && th->cwr)
364 inet_rsk(req)->ecn_ok = 1;
365}
366
367enum tcp_tw_status {
368 TCP_TW_SUCCESS = 0,
369 TCP_TW_RST = 1,
370 TCP_TW_ACK = 2,
371 TCP_TW_SYN = 3
372};
373
374
375extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
376 struct sk_buff *skb,
377 const struct tcphdr *th);
378extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
379 struct request_sock *req,
380 struct request_sock **prev);
381extern int tcp_child_process(struct sock *parent, struct sock *child,
382 struct sk_buff *skb);
383extern int tcp_use_frto(struct sock *sk);
384extern void tcp_enter_frto(struct sock *sk);
385extern void tcp_enter_loss(struct sock *sk, int how);
386extern void tcp_clear_retrans(struct tcp_sock *tp);
387extern void tcp_update_metrics(struct sock *sk);
388extern void tcp_close(struct sock *sk, long timeout);
389extern unsigned int tcp_poll(struct file * file, struct socket *sock,
390 struct poll_table_struct *wait);
391extern int tcp_getsockopt(struct sock *sk, int level, int optname,
392 char __user *optval, int __user *optlen);
393extern int tcp_setsockopt(struct sock *sk, int level, int optname,
394 char __user *optval, unsigned int optlen);
395extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399extern void tcp_set_keepalive(struct sock *sk, int val);
400extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
401extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
402 size_t len, int nonblock, int flags, int *addr_len);
403extern void tcp_parse_options(struct sk_buff *skb,
404 struct tcp_options_received *opt_rx, u8 **hvpp,
405 int estab);
406extern u8 *tcp_parse_md5sig_option(struct tcphdr *th);
407
408/*
409 * TCP v4 functions exported for the inet6 API
410 */
411
412extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
413extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
414extern struct sock * tcp_create_openreq_child(struct sock *sk,
415 struct request_sock *req,
416 struct sk_buff *skb);
417extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
418 struct request_sock *req,
419 struct dst_entry *dst);
420extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
421extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
422 int addr_len);
423extern int tcp_connect(struct sock *sk);
424extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
425 struct request_sock *req,
426 struct request_values *rvp);
427extern int tcp_disconnect(struct sock *sk, int flags);
428
429
430/* From syncookies.c */
431extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
432extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
433 struct ip_options *opt);
434#ifdef CONFIG_SYN_COOKIES
435extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
436 __u16 *mss);
437#else
438static inline __u32 cookie_v4_init_sequence(struct sock *sk,
439 struct sk_buff *skb,
440 __u16 *mss)
441{
442 return 0;
443}
444#endif
445
446extern __u32 cookie_init_timestamp(struct request_sock *req);
447extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
448
449/* From net/ipv6/syncookies.c */
450extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
451#ifdef CONFIG_SYN_COOKIES
452extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb,
453 __u16 *mss);
454#else
455static inline __u32 cookie_v6_init_sequence(struct sock *sk,
456 struct sk_buff *skb,
457 __u16 *mss)
458{
459 return 0;
460}
461#endif
462/* tcp_output.c */
463
464extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
465 int nonagle);
466extern int tcp_may_send_now(struct sock *sk);
467extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
468extern void tcp_retransmit_timer(struct sock *sk);
469extern void tcp_xmit_retransmit_queue(struct sock *);
470extern void tcp_simple_retransmit(struct sock *);
471extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
472extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
473
474extern void tcp_send_probe0(struct sock *);
475extern void tcp_send_partial(struct sock *);
476extern int tcp_write_wakeup(struct sock *);
477extern void tcp_send_fin(struct sock *sk);
478extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
479extern int tcp_send_synack(struct sock *);
480extern int tcp_syn_flood_action(struct sock *sk,
481 const struct sk_buff *skb,
482 const char *proto);
483extern void tcp_push_one(struct sock *, unsigned int mss_now);
484extern void tcp_send_ack(struct sock *sk);
485extern void tcp_send_delayed_ack(struct sock *sk);
486
487/* tcp_input.c */
488extern void tcp_cwnd_application_limited(struct sock *sk);
489
490/* tcp_timer.c */
491extern void tcp_init_xmit_timers(struct sock *);
492static inline void tcp_clear_xmit_timers(struct sock *sk)
493{
494 inet_csk_clear_xmit_timers(sk);
495}
496
497extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
498extern unsigned int tcp_current_mss(struct sock *sk);
499
500/* Bound MSS / TSO packet size with the half of the window */
501static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
502{
503 int cutoff;
504
505 /* When peer uses tiny windows, there is no use in packetizing
506 * to sub-MSS pieces for the sake of SWS or making sure there
507 * are enough packets in the pipe for fast recovery.
508 *
509 * On the other hand, for extremely large MSS devices, handling
510 * smaller than MSS windows in this way does make sense.
511 */
512 if (tp->max_window >= 512)
513 cutoff = (tp->max_window >> 1);
514 else
515 cutoff = tp->max_window;
516
517 if (cutoff && pktsize > cutoff)
518 return max_t(int, cutoff, 68U - tp->tcp_header_len);
519 else
520 return pktsize;
521}
522
523/* tcp.c */
524extern void tcp_get_info(struct sock *, struct tcp_info *);
525
526/* Read 'sendfile()'-style from a TCP socket */
527typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
528 unsigned int, size_t);
529extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
530 sk_read_actor_t recv_actor);
531
532extern void tcp_initialize_rcv_mss(struct sock *sk);
533
534extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
535extern int tcp_mss_to_mtu(struct sock *sk, int mss);
536extern void tcp_mtup_init(struct sock *sk);
537extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
538
539static inline void tcp_bound_rto(const struct sock *sk)
540{
541 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
542 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
543}
544
545static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
546{
547 return (tp->srtt >> 3) + tp->rttvar;
548}
549
550static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
551{
552 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
553 ntohl(TCP_FLAG_ACK) |
554 snd_wnd);
555}
556
557static inline void tcp_fast_path_on(struct tcp_sock *tp)
558{
559 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
560}
561
562static inline void tcp_fast_path_check(struct sock *sk)
563{
564 struct tcp_sock *tp = tcp_sk(sk);
565
566 if (skb_queue_empty(&tp->out_of_order_queue) &&
567 tp->rcv_wnd &&
568 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
569 !tp->urg_data)
570 tcp_fast_path_on(tp);
571}
572
573/* Compute the actual rto_min value */
574static inline u32 tcp_rto_min(struct sock *sk)
575{
576 struct dst_entry *dst = __sk_dst_get(sk);
577 u32 rto_min = TCP_RTO_MIN;
578
579 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
580 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
581 return rto_min;
582}
583
584/* Compute the actual receive window we are currently advertising.
585 * Rcv_nxt can be after the window if our peer push more data
586 * than the offered window.
587 */
588static inline u32 tcp_receive_window(const struct tcp_sock *tp)
589{
590 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
591
592 if (win < 0)
593 win = 0;
594 return (u32) win;
595}
596
597/* Choose a new window, without checks for shrinking, and without
598 * scaling applied to the result. The caller does these things
599 * if necessary. This is a "raw" window selection.
600 */
601extern u32 __tcp_select_window(struct sock *sk);
602
603/* TCP timestamps are only 32-bits, this causes a slight
604 * complication on 64-bit systems since we store a snapshot
605 * of jiffies in the buffer control blocks below. We decided
606 * to use only the low 32-bits of jiffies and hide the ugly
607 * casts with the following macro.
608 */
609#define tcp_time_stamp ((__u32)(jiffies))
610
611#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
612
613#define TCPHDR_FIN 0x01
614#define TCPHDR_SYN 0x02
615#define TCPHDR_RST 0x04
616#define TCPHDR_PSH 0x08
617#define TCPHDR_ACK 0x10
618#define TCPHDR_URG 0x20
619#define TCPHDR_ECE 0x40
620#define TCPHDR_CWR 0x80
621
622/* This is what the send packet queuing engine uses to pass
623 * TCP per-packet control information to the transmission code.
624 * We also store the host-order sequence numbers in here too.
625 * This is 44 bytes if IPV6 is enabled.
626 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
627 */
628struct tcp_skb_cb {
629 union {
630 struct inet_skb_parm h4;
631#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
632 struct inet6_skb_parm h6;
633#endif
634 } header; /* For incoming frames */
635 __u32 seq; /* Starting sequence number */
636 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
637 __u32 when; /* used to compute rtt's */
638 __u8 flags; /* TCP header flags. */
639 __u8 sacked; /* State flags for SACK/FACK. */
640#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
641#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
642#define TCPCB_LOST 0x04 /* SKB is lost */
643#define TCPCB_TAGBITS 0x07 /* All tag bits */
644
645#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
646#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
647
648 __u32 ack_seq; /* Sequence number ACK'd */
649};
650
651#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
652
653/* Due to TSO, an SKB can be composed of multiple actual
654 * packets. To keep these tracked properly, we use this.
655 */
656static inline int tcp_skb_pcount(const struct sk_buff *skb)
657{
658 return skb_shinfo(skb)->gso_segs;
659}
660
661/* This is valid iff tcp_skb_pcount() > 1. */
662static inline int tcp_skb_mss(const struct sk_buff *skb)
663{
664 return skb_shinfo(skb)->gso_size;
665}
666
667/* Events passed to congestion control interface */
668enum tcp_ca_event {
669 CA_EVENT_TX_START, /* first transmit when no packets in flight */
670 CA_EVENT_CWND_RESTART, /* congestion window restart */
671 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
672 CA_EVENT_FRTO, /* fast recovery timeout */
673 CA_EVENT_LOSS, /* loss timeout */
674 CA_EVENT_FAST_ACK, /* in sequence ack */
675 CA_EVENT_SLOW_ACK, /* other ack */
676};
677
678/*
679 * Interface for adding new TCP congestion control handlers
680 */
681#define TCP_CA_NAME_MAX 16
682#define TCP_CA_MAX 128
683#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
684
685#define TCP_CONG_NON_RESTRICTED 0x1
686#define TCP_CONG_RTT_STAMP 0x2
687
688struct tcp_congestion_ops {
689 struct list_head list;
690 unsigned long flags;
691
692 /* initialize private data (optional) */
693 void (*init)(struct sock *sk);
694 /* cleanup private data (optional) */
695 void (*release)(struct sock *sk);
696
697 /* return slow start threshold (required) */
698 u32 (*ssthresh)(struct sock *sk);
699 /* lower bound for congestion window (optional) */
700 u32 (*min_cwnd)(const struct sock *sk);
701 /* do new cwnd calculation (required) */
702 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
703 /* call before changing ca_state (optional) */
704 void (*set_state)(struct sock *sk, u8 new_state);
705 /* call when cwnd event occurs (optional) */
706 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
707 /* new value of cwnd after loss (optional) */
708 u32 (*undo_cwnd)(struct sock *sk);
709 /* hook for packet ack accounting (optional) */
710 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
711 /* get info for inet_diag (optional) */
712 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
713
714 char name[TCP_CA_NAME_MAX];
715 struct module *owner;
716};
717
718extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
719extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
720
721extern void tcp_init_congestion_control(struct sock *sk);
722extern void tcp_cleanup_congestion_control(struct sock *sk);
723extern int tcp_set_default_congestion_control(const char *name);
724extern void tcp_get_default_congestion_control(char *name);
725extern void tcp_get_available_congestion_control(char *buf, size_t len);
726extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
727extern int tcp_set_allowed_congestion_control(char *allowed);
728extern int tcp_set_congestion_control(struct sock *sk, const char *name);
729extern void tcp_slow_start(struct tcp_sock *tp);
730extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
731
732extern struct tcp_congestion_ops tcp_init_congestion_ops;
733extern u32 tcp_reno_ssthresh(struct sock *sk);
734extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
735extern u32 tcp_reno_min_cwnd(const struct sock *sk);
736extern struct tcp_congestion_ops tcp_reno;
737
738static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
739{
740 struct inet_connection_sock *icsk = inet_csk(sk);
741
742 if (icsk->icsk_ca_ops->set_state)
743 icsk->icsk_ca_ops->set_state(sk, ca_state);
744 icsk->icsk_ca_state = ca_state;
745}
746
747static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
748{
749 const struct inet_connection_sock *icsk = inet_csk(sk);
750
751 if (icsk->icsk_ca_ops->cwnd_event)
752 icsk->icsk_ca_ops->cwnd_event(sk, event);
753}
754
755/* These functions determine how the current flow behaves in respect of SACK
756 * handling. SACK is negotiated with the peer, and therefore it can vary
757 * between different flows.
758 *
759 * tcp_is_sack - SACK enabled
760 * tcp_is_reno - No SACK
761 * tcp_is_fack - FACK enabled, implies SACK enabled
762 */
763static inline int tcp_is_sack(const struct tcp_sock *tp)
764{
765 return tp->rx_opt.sack_ok;
766}
767
768static inline int tcp_is_reno(const struct tcp_sock *tp)
769{
770 return !tcp_is_sack(tp);
771}
772
773static inline int tcp_is_fack(const struct tcp_sock *tp)
774{
775 return tp->rx_opt.sack_ok & 2;
776}
777
778static inline void tcp_enable_fack(struct tcp_sock *tp)
779{
780 tp->rx_opt.sack_ok |= 2;
781}
782
783static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
784{
785 return tp->sacked_out + tp->lost_out;
786}
787
788/* This determines how many packets are "in the network" to the best
789 * of our knowledge. In many cases it is conservative, but where
790 * detailed information is available from the receiver (via SACK
791 * blocks etc.) we can make more aggressive calculations.
792 *
793 * Use this for decisions involving congestion control, use just
794 * tp->packets_out to determine if the send queue is empty or not.
795 *
796 * Read this equation as:
797 *
798 * "Packets sent once on transmission queue" MINUS
799 * "Packets left network, but not honestly ACKed yet" PLUS
800 * "Packets fast retransmitted"
801 */
802static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
803{
804 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
805}
806
807#define TCP_INFINITE_SSTHRESH 0x7fffffff
808
809static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
810{
811 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
812}
813
814/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
815 * The exception is rate halving phase, when cwnd is decreasing towards
816 * ssthresh.
817 */
818static inline __u32 tcp_current_ssthresh(const struct sock *sk)
819{
820 const struct tcp_sock *tp = tcp_sk(sk);
821 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
822 return tp->snd_ssthresh;
823 else
824 return max(tp->snd_ssthresh,
825 ((tp->snd_cwnd >> 1) +
826 (tp->snd_cwnd >> 2)));
827}
828
829/* Use define here intentionally to get WARN_ON location shown at the caller */
830#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
831
832extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
833extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
834
835/* Slow start with delack produces 3 packets of burst, so that
836 * it is safe "de facto". This will be the default - same as
837 * the default reordering threshold - but if reordering increases,
838 * we must be able to allow cwnd to burst at least this much in order
839 * to not pull it back when holes are filled.
840 */
841static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
842{
843 return tp->reordering;
844}
845
846/* Returns end sequence number of the receiver's advertised window */
847static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
848{
849 return tp->snd_una + tp->snd_wnd;
850}
851extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
852
853static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
854 const struct sk_buff *skb)
855{
856 if (skb->len < mss)
857 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
858}
859
860static inline void tcp_check_probe_timer(struct sock *sk)
861{
862 struct tcp_sock *tp = tcp_sk(sk);
863 const struct inet_connection_sock *icsk = inet_csk(sk);
864
865 if (!tp->packets_out && !icsk->icsk_pending)
866 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
867 icsk->icsk_rto, TCP_RTO_MAX);
868}
869
870static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
871{
872 tp->snd_wl1 = seq;
873}
874
875static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
876{
877 tp->snd_wl1 = seq;
878}
879
880/*
881 * Calculate(/check) TCP checksum
882 */
883static inline __sum16 tcp_v4_check(int len, __be32 saddr,
884 __be32 daddr, __wsum base)
885{
886 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
887}
888
889static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
890{
891 return __skb_checksum_complete(skb);
892}
893
894static inline int tcp_checksum_complete(struct sk_buff *skb)
895{
896 return !skb_csum_unnecessary(skb) &&
897 __tcp_checksum_complete(skb);
898}
899
900/* Prequeue for VJ style copy to user, combined with checksumming. */
901
902static inline void tcp_prequeue_init(struct tcp_sock *tp)
903{
904 tp->ucopy.task = NULL;
905 tp->ucopy.len = 0;
906 tp->ucopy.memory = 0;
907 skb_queue_head_init(&tp->ucopy.prequeue);
908#ifdef CONFIG_NET_DMA
909 tp->ucopy.dma_chan = NULL;
910 tp->ucopy.wakeup = 0;
911 tp->ucopy.pinned_list = NULL;
912 tp->ucopy.dma_cookie = 0;
913#endif
914}
915
916/* Packet is added to VJ-style prequeue for processing in process
917 * context, if a reader task is waiting. Apparently, this exciting
918 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
919 * failed somewhere. Latency? Burstiness? Well, at least now we will
920 * see, why it failed. 8)8) --ANK
921 *
922 * NOTE: is this not too big to inline?
923 */
924static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
925{
926 struct tcp_sock *tp = tcp_sk(sk);
927
928 if (sysctl_tcp_low_latency || !tp->ucopy.task)
929 return 0;
930
931 __skb_queue_tail(&tp->ucopy.prequeue, skb);
932 tp->ucopy.memory += skb->truesize;
933 if (tp->ucopy.memory > sk->sk_rcvbuf) {
934 struct sk_buff *skb1;
935
936 BUG_ON(sock_owned_by_user(sk));
937
938 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
939 sk_backlog_rcv(sk, skb1);
940 NET_INC_STATS_BH(sock_net(sk),
941 LINUX_MIB_TCPPREQUEUEDROPPED);
942 }
943
944 tp->ucopy.memory = 0;
945 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
946 wake_up_interruptible_sync_poll(sk_sleep(sk),
947 POLLIN | POLLRDNORM | POLLRDBAND);
948 if (!inet_csk_ack_scheduled(sk))
949 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
950 (3 * tcp_rto_min(sk)) / 4,
951 TCP_RTO_MAX);
952 }
953 return 1;
954}
955
956
957#undef STATE_TRACE
958
959#ifdef STATE_TRACE
960static const char *statename[]={
961 "Unused","Established","Syn Sent","Syn Recv",
962 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
963 "Close Wait","Last ACK","Listen","Closing"
964};
965#endif
966extern void tcp_set_state(struct sock *sk, int state);
967
968extern void tcp_done(struct sock *sk);
969
970static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
971{
972 rx_opt->dsack = 0;
973 rx_opt->num_sacks = 0;
974}
975
976/* Determine a window scaling and initial window to offer. */
977extern void tcp_select_initial_window(int __space, __u32 mss,
978 __u32 *rcv_wnd, __u32 *window_clamp,
979 int wscale_ok, __u8 *rcv_wscale,
980 __u32 init_rcv_wnd);
981
982static inline int tcp_win_from_space(int space)
983{
984 return sysctl_tcp_adv_win_scale<=0 ?
985 (space>>(-sysctl_tcp_adv_win_scale)) :
986 space - (space>>sysctl_tcp_adv_win_scale);
987}
988
989/* Note: caller must be prepared to deal with negative returns */
990static inline int tcp_space(const struct sock *sk)
991{
992 return tcp_win_from_space(sk->sk_rcvbuf -
993 atomic_read(&sk->sk_rmem_alloc));
994}
995
996static inline int tcp_full_space(const struct sock *sk)
997{
998 return tcp_win_from_space(sk->sk_rcvbuf);
999}
1000
1001static inline void tcp_openreq_init(struct request_sock *req,
1002 struct tcp_options_received *rx_opt,
1003 struct sk_buff *skb)
1004{
1005 struct inet_request_sock *ireq = inet_rsk(req);
1006
1007 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1008 req->cookie_ts = 0;
1009 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1010 req->mss = rx_opt->mss_clamp;
1011 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1012 ireq->tstamp_ok = rx_opt->tstamp_ok;
1013 ireq->sack_ok = rx_opt->sack_ok;
1014 ireq->snd_wscale = rx_opt->snd_wscale;
1015 ireq->wscale_ok = rx_opt->wscale_ok;
1016 ireq->acked = 0;
1017 ireq->ecn_ok = 0;
1018 ireq->rmt_port = tcp_hdr(skb)->source;
1019 ireq->loc_port = tcp_hdr(skb)->dest;
1020}
1021
1022extern void tcp_enter_memory_pressure(struct sock *sk);
1023
1024static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1025{
1026 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1027}
1028
1029static inline int keepalive_time_when(const struct tcp_sock *tp)
1030{
1031 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1032}
1033
1034static inline int keepalive_probes(const struct tcp_sock *tp)
1035{
1036 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1037}
1038
1039static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1040{
1041 const struct inet_connection_sock *icsk = &tp->inet_conn;
1042
1043 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1044 tcp_time_stamp - tp->rcv_tstamp);
1045}
1046
1047static inline int tcp_fin_time(const struct sock *sk)
1048{
1049 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1050 const int rto = inet_csk(sk)->icsk_rto;
1051
1052 if (fin_timeout < (rto << 2) - (rto >> 1))
1053 fin_timeout = (rto << 2) - (rto >> 1);
1054
1055 return fin_timeout;
1056}
1057
1058static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1059 int paws_win)
1060{
1061 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1062 return 1;
1063 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1064 return 1;
1065 /*
1066 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1067 * then following tcp messages have valid values. Ignore 0 value,
1068 * or else 'negative' tsval might forbid us to accept their packets.
1069 */
1070 if (!rx_opt->ts_recent)
1071 return 1;
1072 return 0;
1073}
1074
1075static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1076 int rst)
1077{
1078 if (tcp_paws_check(rx_opt, 0))
1079 return 0;
1080
1081 /* RST segments are not recommended to carry timestamp,
1082 and, if they do, it is recommended to ignore PAWS because
1083 "their cleanup function should take precedence over timestamps."
1084 Certainly, it is mistake. It is necessary to understand the reasons
1085 of this constraint to relax it: if peer reboots, clock may go
1086 out-of-sync and half-open connections will not be reset.
1087 Actually, the problem would be not existing if all
1088 the implementations followed draft about maintaining clock
1089 via reboots. Linux-2.2 DOES NOT!
1090
1091 However, we can relax time bounds for RST segments to MSL.
1092 */
1093 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1094 return 0;
1095 return 1;
1096}
1097
1098static inline void tcp_mib_init(struct net *net)
1099{
1100 /* See RFC 2012 */
1101 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1102 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1103 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1104 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1105}
1106
1107/* from STCP */
1108static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1109{
1110 tp->lost_skb_hint = NULL;
1111 tp->scoreboard_skb_hint = NULL;
1112}
1113
1114static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1115{
1116 tcp_clear_retrans_hints_partial(tp);
1117 tp->retransmit_skb_hint = NULL;
1118}
1119
1120/* MD5 Signature */
1121struct crypto_hash;
1122
1123/* - key database */
1124struct tcp_md5sig_key {
1125 u8 *key;
1126 u8 keylen;
1127};
1128
1129struct tcp4_md5sig_key {
1130 struct tcp_md5sig_key base;
1131 __be32 addr;
1132};
1133
1134struct tcp6_md5sig_key {
1135 struct tcp_md5sig_key base;
1136#if 0
1137 u32 scope_id; /* XXX */
1138#endif
1139 struct in6_addr addr;
1140};
1141
1142/* - sock block */
1143struct tcp_md5sig_info {
1144 struct tcp4_md5sig_key *keys4;
1145#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1146 struct tcp6_md5sig_key *keys6;
1147 u32 entries6;
1148 u32 alloced6;
1149#endif
1150 u32 entries4;
1151 u32 alloced4;
1152};
1153
1154/* - pseudo header */
1155struct tcp4_pseudohdr {
1156 __be32 saddr;
1157 __be32 daddr;
1158 __u8 pad;
1159 __u8 protocol;
1160 __be16 len;
1161};
1162
1163struct tcp6_pseudohdr {
1164 struct in6_addr saddr;
1165 struct in6_addr daddr;
1166 __be32 len;
1167 __be32 protocol; /* including padding */
1168};
1169
1170union tcp_md5sum_block {
1171 struct tcp4_pseudohdr ip4;
1172#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1173 struct tcp6_pseudohdr ip6;
1174#endif
1175};
1176
1177/* - pool: digest algorithm, hash description and scratch buffer */
1178struct tcp_md5sig_pool {
1179 struct hash_desc md5_desc;
1180 union tcp_md5sum_block md5_blk;
1181};
1182
1183/* - functions */
1184extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1185 struct sock *sk, struct request_sock *req,
1186 struct sk_buff *skb);
1187extern struct tcp_md5sig_key * tcp_v4_md5_lookup(struct sock *sk,
1188 struct sock *addr_sk);
1189extern int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, u8 *newkey,
1190 u8 newkeylen);
1191extern int tcp_v4_md5_do_del(struct sock *sk, __be32 addr);
1192
1193#ifdef CONFIG_TCP_MD5SIG
1194#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \
1195 &(struct tcp_md5sig_key) { \
1196 .key = (twsk)->tw_md5_key, \
1197 .keylen = (twsk)->tw_md5_keylen, \
1198 } : NULL)
1199#else
1200#define tcp_twsk_md5_key(twsk) NULL
1201#endif
1202
1203extern struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *);
1204extern void tcp_free_md5sig_pool(void);
1205
1206extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1207extern void tcp_put_md5sig_pool(void);
1208
1209extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *);
1210extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, struct sk_buff *,
1211 unsigned header_len);
1212extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1213 struct tcp_md5sig_key *key);
1214
1215/* write queue abstraction */
1216static inline void tcp_write_queue_purge(struct sock *sk)
1217{
1218 struct sk_buff *skb;
1219
1220 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1221 sk_wmem_free_skb(sk, skb);
1222 sk_mem_reclaim(sk);
1223 tcp_clear_all_retrans_hints(tcp_sk(sk));
1224}
1225
1226static inline struct sk_buff *tcp_write_queue_head(struct sock *sk)
1227{
1228 return skb_peek(&sk->sk_write_queue);
1229}
1230
1231static inline struct sk_buff *tcp_write_queue_tail(struct sock *sk)
1232{
1233 return skb_peek_tail(&sk->sk_write_queue);
1234}
1235
1236static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_buff *skb)
1237{
1238 return skb_queue_next(&sk->sk_write_queue, skb);
1239}
1240
1241static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_buff *skb)
1242{
1243 return skb_queue_prev(&sk->sk_write_queue, skb);
1244}
1245
1246#define tcp_for_write_queue(skb, sk) \
1247 skb_queue_walk(&(sk)->sk_write_queue, skb)
1248
1249#define tcp_for_write_queue_from(skb, sk) \
1250 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1251
1252#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1253 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1254
1255static inline struct sk_buff *tcp_send_head(struct sock *sk)
1256{
1257 return sk->sk_send_head;
1258}
1259
1260static inline bool tcp_skb_is_last(const struct sock *sk,
1261 const struct sk_buff *skb)
1262{
1263 return skb_queue_is_last(&sk->sk_write_queue, skb);
1264}
1265
1266static inline void tcp_advance_send_head(struct sock *sk, struct sk_buff *skb)
1267{
1268 if (tcp_skb_is_last(sk, skb))
1269 sk->sk_send_head = NULL;
1270 else
1271 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1272}
1273
1274static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1275{
1276 if (sk->sk_send_head == skb_unlinked)
1277 sk->sk_send_head = NULL;
1278}
1279
1280static inline void tcp_init_send_head(struct sock *sk)
1281{
1282 sk->sk_send_head = NULL;
1283}
1284
1285static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1286{
1287 __skb_queue_tail(&sk->sk_write_queue, skb);
1288}
1289
1290static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1291{
1292 __tcp_add_write_queue_tail(sk, skb);
1293
1294 /* Queue it, remembering where we must start sending. */
1295 if (sk->sk_send_head == NULL) {
1296 sk->sk_send_head = skb;
1297
1298 if (tcp_sk(sk)->highest_sack == NULL)
1299 tcp_sk(sk)->highest_sack = skb;
1300 }
1301}
1302
1303static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1304{
1305 __skb_queue_head(&sk->sk_write_queue, skb);
1306}
1307
1308/* Insert buff after skb on the write queue of sk. */
1309static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1310 struct sk_buff *buff,
1311 struct sock *sk)
1312{
1313 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1314}
1315
1316/* Insert new before skb on the write queue of sk. */
1317static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1318 struct sk_buff *skb,
1319 struct sock *sk)
1320{
1321 __skb_queue_before(&sk->sk_write_queue, skb, new);
1322
1323 if (sk->sk_send_head == skb)
1324 sk->sk_send_head = new;
1325}
1326
1327static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1328{
1329 __skb_unlink(skb, &sk->sk_write_queue);
1330}
1331
1332static inline int tcp_write_queue_empty(struct sock *sk)
1333{
1334 return skb_queue_empty(&sk->sk_write_queue);
1335}
1336
1337static inline void tcp_push_pending_frames(struct sock *sk)
1338{
1339 if (tcp_send_head(sk)) {
1340 struct tcp_sock *tp = tcp_sk(sk);
1341
1342 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1343 }
1344}
1345
1346/* Start sequence of the highest skb with SACKed bit, valid only if
1347 * sacked > 0 or when the caller has ensured validity by itself.
1348 */
1349static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1350{
1351 if (!tp->sacked_out)
1352 return tp->snd_una;
1353
1354 if (tp->highest_sack == NULL)
1355 return tp->snd_nxt;
1356
1357 return TCP_SKB_CB(tp->highest_sack)->seq;
1358}
1359
1360static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1361{
1362 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1363 tcp_write_queue_next(sk, skb);
1364}
1365
1366static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1367{
1368 return tcp_sk(sk)->highest_sack;
1369}
1370
1371static inline void tcp_highest_sack_reset(struct sock *sk)
1372{
1373 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1374}
1375
1376/* Called when old skb is about to be deleted (to be combined with new skb) */
1377static inline void tcp_highest_sack_combine(struct sock *sk,
1378 struct sk_buff *old,
1379 struct sk_buff *new)
1380{
1381 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1382 tcp_sk(sk)->highest_sack = new;
1383}
1384
1385/* Determines whether this is a thin stream (which may suffer from
1386 * increased latency). Used to trigger latency-reducing mechanisms.
1387 */
1388static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
1389{
1390 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1391}
1392
1393/* /proc */
1394enum tcp_seq_states {
1395 TCP_SEQ_STATE_LISTENING,
1396 TCP_SEQ_STATE_OPENREQ,
1397 TCP_SEQ_STATE_ESTABLISHED,
1398 TCP_SEQ_STATE_TIME_WAIT,
1399};
1400
1401struct tcp_seq_afinfo {
1402 char *name;
1403 sa_family_t family;
1404 struct file_operations seq_fops;
1405 struct seq_operations seq_ops;
1406};
1407
1408struct tcp_iter_state {
1409 struct seq_net_private p;
1410 sa_family_t family;
1411 enum tcp_seq_states state;
1412 struct sock *syn_wait_sk;
1413 int bucket, offset, sbucket, num, uid;
1414 loff_t last_pos;
1415};
1416
1417extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1418extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1419
1420extern struct request_sock_ops tcp_request_sock_ops;
1421extern struct request_sock_ops tcp6_request_sock_ops;
1422
1423extern void tcp_v4_destroy_sock(struct sock *sk);
1424
1425extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1426extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, u32 features);
1427extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1428 struct sk_buff *skb);
1429extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1430 struct sk_buff *skb);
1431extern int tcp_gro_complete(struct sk_buff *skb);
1432extern int tcp4_gro_complete(struct sk_buff *skb);
1433
1434#ifdef CONFIG_PROC_FS
1435extern int tcp4_proc_init(void);
1436extern void tcp4_proc_exit(void);
1437#endif
1438
1439/* TCP af-specific functions */
1440struct tcp_sock_af_ops {
1441#ifdef CONFIG_TCP_MD5SIG
1442 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1443 struct sock *addr_sk);
1444 int (*calc_md5_hash) (char *location,
1445 struct tcp_md5sig_key *md5,
1446 struct sock *sk,
1447 struct request_sock *req,
1448 struct sk_buff *skb);
1449 int (*md5_add) (struct sock *sk,
1450 struct sock *addr_sk,
1451 u8 *newkey,
1452 u8 len);
1453 int (*md5_parse) (struct sock *sk,
1454 char __user *optval,
1455 int optlen);
1456#endif
1457};
1458
1459struct tcp_request_sock_ops {
1460#ifdef CONFIG_TCP_MD5SIG
1461 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1462 struct request_sock *req);
1463 int (*calc_md5_hash) (char *location,
1464 struct tcp_md5sig_key *md5,
1465 struct sock *sk,
1466 struct request_sock *req,
1467 struct sk_buff *skb);
1468#endif
1469};
1470
1471/* Using SHA1 for now, define some constants.
1472 */
1473#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1474#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1475#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1476
1477extern int tcp_cookie_generator(u32 *bakery);
1478
1479/**
1480 * struct tcp_cookie_values - each socket needs extra space for the
1481 * cookies, together with (optional) space for any SYN data.
1482 *
1483 * A tcp_sock contains a pointer to the current value, and this is
1484 * cloned to the tcp_timewait_sock.
1485 *
1486 * @cookie_pair: variable data from the option exchange.
1487 *
1488 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1489 * indicates default (sysctl_tcp_cookie_size).
1490 * After cookie sent, remembers size of cookie.
1491 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1492 *
1493 * @s_data_desired: user specified tcpct_s_data_desired. When the
1494 * constant payload is specified (@s_data_constant),
1495 * holds its length instead.
1496 * Range 0 to TCP_MSS_DESIRED.
1497 *
1498 * @s_data_payload: constant data that is to be included in the
1499 * payload of SYN or SYNACK segments when the
1500 * cookie option is present.
1501 */
1502struct tcp_cookie_values {
1503 struct kref kref;
1504 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1505 u8 cookie_pair_size;
1506 u8 cookie_desired;
1507 u16 s_data_desired:11,
1508 s_data_constant:1,
1509 s_data_in:1,
1510 s_data_out:1,
1511 s_data_unused:2;
1512 u8 s_data_payload[0];
1513};
1514
1515static inline void tcp_cookie_values_release(struct kref *kref)
1516{
1517 kfree(container_of(kref, struct tcp_cookie_values, kref));
1518}
1519
1520/* The length of constant payload data. Note that s_data_desired is
1521 * overloaded, depending on s_data_constant: either the length of constant
1522 * data (returned here) or the limit on variable data.
1523 */
1524static inline int tcp_s_data_size(const struct tcp_sock *tp)
1525{
1526 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1527 ? tp->cookie_values->s_data_desired
1528 : 0;
1529}
1530
1531/**
1532 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1533 *
1534 * As tcp_request_sock has already been extended in other places, the
1535 * only remaining method is to pass stack values along as function
1536 * parameters. These parameters are not needed after sending SYNACK.
1537 *
1538 * @cookie_bakery: cryptographic secret and message workspace.
1539 *
1540 * @cookie_plus: bytes in authenticator/cookie option, copied from
1541 * struct tcp_options_received (above).
1542 */
1543struct tcp_extend_values {
1544 struct request_values rv;
1545 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1546 u8 cookie_plus:6,
1547 cookie_out_never:1,
1548 cookie_in_always:1;
1549};
1550
1551static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1552{
1553 return (struct tcp_extend_values *)rvp;
1554}
1555
1556extern void tcp_v4_init(void);
1557extern void tcp_init(void);
1558
1559#endif /* _TCP_H */
1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define FASTRETRANS_DEBUG 1
22
23#include <linux/list.h>
24#include <linux/tcp.h>
25#include <linux/bug.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
29#include <linux/skbuff.h>
30#include <linux/cryptohash.h>
31#include <linux/kref.h>
32#include <linux/ktime.h>
33
34#include <net/inet_connection_sock.h>
35#include <net/inet_timewait_sock.h>
36#include <net/inet_hashtables.h>
37#include <net/checksum.h>
38#include <net/request_sock.h>
39#include <net/sock.h>
40#include <net/snmp.h>
41#include <net/ip.h>
42#include <net/tcp_states.h>
43#include <net/inet_ecn.h>
44#include <net/dst.h>
45
46#include <linux/seq_file.h>
47#include <linux/memcontrol.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER (128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56
57/*
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
60 */
61#define MAX_TCP_WINDOW 32767U
62
63/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
64#define TCP_MIN_MSS 88U
65
66/* The least MTU to use for probing */
67#define TCP_BASE_MSS 1024
68
69/* probing interval, default to 10 minutes as per RFC4821 */
70#define TCP_PROBE_INTERVAL 600
71
72/* Specify interval when tcp mtu probing will stop */
73#define TCP_PROBE_THRESHOLD 8
74
75/* After receiving this amount of duplicate ACKs fast retransmit starts. */
76#define TCP_FASTRETRANS_THRESH 3
77
78/* Maximal number of ACKs sent quickly to accelerate slow-start. */
79#define TCP_MAX_QUICKACKS 16U
80
81/* urg_data states */
82#define TCP_URG_VALID 0x0100
83#define TCP_URG_NOTYET 0x0200
84#define TCP_URG_READ 0x0400
85
86#define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
91 */
92
93#define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
98 */
99
100#define TCP_SYN_RETRIES 6 /* This is how many retries are done
101 * when active opening a connection.
102 * RFC1122 says the minimum retry MUST
103 * be at least 180secs. Nevertheless
104 * this value is corresponding to
105 * 63secs of retransmission with the
106 * current initial RTO.
107 */
108
109#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
110 * when passive opening a connection.
111 * This is corresponding to 31secs of
112 * retransmission with the current
113 * initial RTO.
114 */
115
116#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
117 * state, about 60 seconds */
118#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
119 /* BSD style FIN_WAIT2 deadlock breaker.
120 * It used to be 3min, new value is 60sec,
121 * to combine FIN-WAIT-2 timeout with
122 * TIME-WAIT timer.
123 */
124
125#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
126#if HZ >= 100
127#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
128#define TCP_ATO_MIN ((unsigned)(HZ/25))
129#else
130#define TCP_DELACK_MIN 4U
131#define TCP_ATO_MIN 4U
132#endif
133#define TCP_RTO_MAX ((unsigned)(120*HZ))
134#define TCP_RTO_MIN ((unsigned)(HZ/5))
135#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
136#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
137 * used as a fallback RTO for the
138 * initial data transmission if no
139 * valid RTT sample has been acquired,
140 * most likely due to retrans in 3WHS.
141 */
142
143#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
144 * for local resources.
145 */
146
147#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
148#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
149#define TCP_KEEPALIVE_INTVL (75*HZ)
150
151#define MAX_TCP_KEEPIDLE 32767
152#define MAX_TCP_KEEPINTVL 32767
153#define MAX_TCP_KEEPCNT 127
154#define MAX_TCP_SYNCNT 127
155
156#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
157
158#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
159#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
160 * after this time. It should be equal
161 * (or greater than) TCP_TIMEWAIT_LEN
162 * to provide reliability equal to one
163 * provided by timewait state.
164 */
165#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
166 * timestamps. It must be less than
167 * minimal timewait lifetime.
168 */
169/*
170 * TCP option
171 */
172
173#define TCPOPT_NOP 1 /* Padding */
174#define TCPOPT_EOL 0 /* End of options */
175#define TCPOPT_MSS 2 /* Segment size negotiating */
176#define TCPOPT_WINDOW 3 /* Window scaling */
177#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
178#define TCPOPT_SACK 5 /* SACK Block */
179#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
180#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
181#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
182#define TCPOPT_EXP 254 /* Experimental */
183/* Magic number to be after the option value for sharing TCP
184 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
185 */
186#define TCPOPT_FASTOPEN_MAGIC 0xF989
187
188/*
189 * TCP option lengths
190 */
191
192#define TCPOLEN_MSS 4
193#define TCPOLEN_WINDOW 3
194#define TCPOLEN_SACK_PERM 2
195#define TCPOLEN_TIMESTAMP 10
196#define TCPOLEN_MD5SIG 18
197#define TCPOLEN_FASTOPEN_BASE 2
198#define TCPOLEN_EXP_FASTOPEN_BASE 4
199
200/* But this is what stacks really send out. */
201#define TCPOLEN_TSTAMP_ALIGNED 12
202#define TCPOLEN_WSCALE_ALIGNED 4
203#define TCPOLEN_SACKPERM_ALIGNED 4
204#define TCPOLEN_SACK_BASE 2
205#define TCPOLEN_SACK_BASE_ALIGNED 4
206#define TCPOLEN_SACK_PERBLOCK 8
207#define TCPOLEN_MD5SIG_ALIGNED 20
208#define TCPOLEN_MSS_ALIGNED 4
209
210/* Flags in tp->nonagle */
211#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
212#define TCP_NAGLE_CORK 2 /* Socket is corked */
213#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
214
215/* TCP thin-stream limits */
216#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
217
218/* TCP initial congestion window as per rfc6928 */
219#define TCP_INIT_CWND 10
220
221/* Bit Flags for sysctl_tcp_fastopen */
222#define TFO_CLIENT_ENABLE 1
223#define TFO_SERVER_ENABLE 2
224#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
225
226/* Accept SYN data w/o any cookie option */
227#define TFO_SERVER_COOKIE_NOT_REQD 0x200
228
229/* Force enable TFO on all listeners, i.e., not requiring the
230 * TCP_FASTOPEN socket option.
231 */
232#define TFO_SERVER_WO_SOCKOPT1 0x400
233
234extern struct inet_timewait_death_row tcp_death_row;
235
236/* sysctl variables for tcp */
237extern int sysctl_tcp_timestamps;
238extern int sysctl_tcp_window_scaling;
239extern int sysctl_tcp_sack;
240extern int sysctl_tcp_fastopen;
241extern int sysctl_tcp_retrans_collapse;
242extern int sysctl_tcp_stdurg;
243extern int sysctl_tcp_rfc1337;
244extern int sysctl_tcp_abort_on_overflow;
245extern int sysctl_tcp_max_orphans;
246extern int sysctl_tcp_fack;
247extern int sysctl_tcp_reordering;
248extern int sysctl_tcp_max_reordering;
249extern int sysctl_tcp_dsack;
250extern long sysctl_tcp_mem[3];
251extern int sysctl_tcp_wmem[3];
252extern int sysctl_tcp_rmem[3];
253extern int sysctl_tcp_app_win;
254extern int sysctl_tcp_adv_win_scale;
255extern int sysctl_tcp_frto;
256extern int sysctl_tcp_low_latency;
257extern int sysctl_tcp_nometrics_save;
258extern int sysctl_tcp_moderate_rcvbuf;
259extern int sysctl_tcp_tso_win_divisor;
260extern int sysctl_tcp_workaround_signed_windows;
261extern int sysctl_tcp_slow_start_after_idle;
262extern int sysctl_tcp_thin_linear_timeouts;
263extern int sysctl_tcp_thin_dupack;
264extern int sysctl_tcp_early_retrans;
265extern int sysctl_tcp_limit_output_bytes;
266extern int sysctl_tcp_challenge_ack_limit;
267extern int sysctl_tcp_min_tso_segs;
268extern int sysctl_tcp_min_rtt_wlen;
269extern int sysctl_tcp_autocorking;
270extern int sysctl_tcp_invalid_ratelimit;
271extern int sysctl_tcp_pacing_ss_ratio;
272extern int sysctl_tcp_pacing_ca_ratio;
273
274extern atomic_long_t tcp_memory_allocated;
275extern struct percpu_counter tcp_sockets_allocated;
276extern int tcp_memory_pressure;
277
278/* optimized version of sk_under_memory_pressure() for TCP sockets */
279static inline bool tcp_under_memory_pressure(const struct sock *sk)
280{
281 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
282 mem_cgroup_under_socket_pressure(sk->sk_memcg))
283 return true;
284
285 return tcp_memory_pressure;
286}
287/*
288 * The next routines deal with comparing 32 bit unsigned ints
289 * and worry about wraparound (automatic with unsigned arithmetic).
290 */
291
292static inline bool before(__u32 seq1, __u32 seq2)
293{
294 return (__s32)(seq1-seq2) < 0;
295}
296#define after(seq2, seq1) before(seq1, seq2)
297
298/* is s2<=s1<=s3 ? */
299static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
300{
301 return seq3 - seq2 >= seq1 - seq2;
302}
303
304static inline bool tcp_out_of_memory(struct sock *sk)
305{
306 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
307 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
308 return true;
309 return false;
310}
311
312void sk_forced_mem_schedule(struct sock *sk, int size);
313
314static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
315{
316 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
317 int orphans = percpu_counter_read_positive(ocp);
318
319 if (orphans << shift > sysctl_tcp_max_orphans) {
320 orphans = percpu_counter_sum_positive(ocp);
321 if (orphans << shift > sysctl_tcp_max_orphans)
322 return true;
323 }
324 return false;
325}
326
327bool tcp_check_oom(struct sock *sk, int shift);
328
329
330extern struct proto tcp_prot;
331
332#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
333#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
334#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
335#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
336
337void tcp_tasklet_init(void);
338
339void tcp_v4_err(struct sk_buff *skb, u32);
340
341void tcp_shutdown(struct sock *sk, int how);
342
343void tcp_v4_early_demux(struct sk_buff *skb);
344int tcp_v4_rcv(struct sk_buff *skb);
345
346int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
347int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
348int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
349 int flags);
350void tcp_release_cb(struct sock *sk);
351void tcp_wfree(struct sk_buff *skb);
352void tcp_write_timer_handler(struct sock *sk);
353void tcp_delack_timer_handler(struct sock *sk);
354int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
355int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
356void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
357 const struct tcphdr *th, unsigned int len);
358void tcp_rcv_space_adjust(struct sock *sk);
359int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
360void tcp_twsk_destructor(struct sock *sk);
361ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
362 struct pipe_inode_info *pipe, size_t len,
363 unsigned int flags);
364
365static inline void tcp_dec_quickack_mode(struct sock *sk,
366 const unsigned int pkts)
367{
368 struct inet_connection_sock *icsk = inet_csk(sk);
369
370 if (icsk->icsk_ack.quick) {
371 if (pkts >= icsk->icsk_ack.quick) {
372 icsk->icsk_ack.quick = 0;
373 /* Leaving quickack mode we deflate ATO. */
374 icsk->icsk_ack.ato = TCP_ATO_MIN;
375 } else
376 icsk->icsk_ack.quick -= pkts;
377 }
378}
379
380#define TCP_ECN_OK 1
381#define TCP_ECN_QUEUE_CWR 2
382#define TCP_ECN_DEMAND_CWR 4
383#define TCP_ECN_SEEN 8
384
385enum tcp_tw_status {
386 TCP_TW_SUCCESS = 0,
387 TCP_TW_RST = 1,
388 TCP_TW_ACK = 2,
389 TCP_TW_SYN = 3
390};
391
392
393enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
394 struct sk_buff *skb,
395 const struct tcphdr *th);
396struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
397 struct request_sock *req, bool fastopen);
398int tcp_child_process(struct sock *parent, struct sock *child,
399 struct sk_buff *skb);
400void tcp_enter_loss(struct sock *sk);
401void tcp_clear_retrans(struct tcp_sock *tp);
402void tcp_update_metrics(struct sock *sk);
403void tcp_init_metrics(struct sock *sk);
404void tcp_metrics_init(void);
405bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
406 bool paws_check, bool timestamps);
407bool tcp_remember_stamp(struct sock *sk);
408bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
409void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
410void tcp_disable_fack(struct tcp_sock *tp);
411void tcp_close(struct sock *sk, long timeout);
412void tcp_init_sock(struct sock *sk);
413unsigned int tcp_poll(struct file *file, struct socket *sock,
414 struct poll_table_struct *wait);
415int tcp_getsockopt(struct sock *sk, int level, int optname,
416 char __user *optval, int __user *optlen);
417int tcp_setsockopt(struct sock *sk, int level, int optname,
418 char __user *optval, unsigned int optlen);
419int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
420 char __user *optval, int __user *optlen);
421int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
422 char __user *optval, unsigned int optlen);
423void tcp_set_keepalive(struct sock *sk, int val);
424void tcp_syn_ack_timeout(const struct request_sock *req);
425int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
426 int flags, int *addr_len);
427void tcp_parse_options(const struct sk_buff *skb,
428 struct tcp_options_received *opt_rx,
429 int estab, struct tcp_fastopen_cookie *foc);
430const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
431
432/*
433 * TCP v4 functions exported for the inet6 API
434 */
435
436void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
437void tcp_v4_mtu_reduced(struct sock *sk);
438void tcp_req_err(struct sock *sk, u32 seq, bool abort);
439int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
440struct sock *tcp_create_openreq_child(const struct sock *sk,
441 struct request_sock *req,
442 struct sk_buff *skb);
443void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
444struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
445 struct request_sock *req,
446 struct dst_entry *dst,
447 struct request_sock *req_unhash,
448 bool *own_req);
449int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
450int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
451int tcp_connect(struct sock *sk);
452enum tcp_synack_type {
453 TCP_SYNACK_NORMAL,
454 TCP_SYNACK_FASTOPEN,
455 TCP_SYNACK_COOKIE,
456};
457struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
458 struct request_sock *req,
459 struct tcp_fastopen_cookie *foc,
460 enum tcp_synack_type synack_type);
461int tcp_disconnect(struct sock *sk, int flags);
462
463void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
464int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
465void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
466
467/* From syncookies.c */
468struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
469 struct request_sock *req,
470 struct dst_entry *dst);
471int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
472 u32 cookie);
473struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
474#ifdef CONFIG_SYN_COOKIES
475
476/* Syncookies use a monotonic timer which increments every 60 seconds.
477 * This counter is used both as a hash input and partially encoded into
478 * the cookie value. A cookie is only validated further if the delta
479 * between the current counter value and the encoded one is less than this,
480 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
481 * the counter advances immediately after a cookie is generated).
482 */
483#define MAX_SYNCOOKIE_AGE 2
484#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
485#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
486
487/* syncookies: remember time of last synqueue overflow
488 * But do not dirty this field too often (once per second is enough)
489 * It is racy as we do not hold a lock, but race is very minor.
490 */
491static inline void tcp_synq_overflow(const struct sock *sk)
492{
493 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
494 unsigned long now = jiffies;
495
496 if (time_after(now, last_overflow + HZ))
497 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
498}
499
500/* syncookies: no recent synqueue overflow on this listening socket? */
501static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
502{
503 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
504
505 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
506}
507
508static inline u32 tcp_cookie_time(void)
509{
510 u64 val = get_jiffies_64();
511
512 do_div(val, TCP_SYNCOOKIE_PERIOD);
513 return val;
514}
515
516u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
517 u16 *mssp);
518__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
519__u32 cookie_init_timestamp(struct request_sock *req);
520bool cookie_timestamp_decode(struct tcp_options_received *opt);
521bool cookie_ecn_ok(const struct tcp_options_received *opt,
522 const struct net *net, const struct dst_entry *dst);
523
524/* From net/ipv6/syncookies.c */
525int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
526 u32 cookie);
527struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
528
529u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
530 const struct tcphdr *th, u16 *mssp);
531__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
532#endif
533/* tcp_output.c */
534
535u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
536 int min_tso_segs);
537void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
538 int nonagle);
539bool tcp_may_send_now(struct sock *sk);
540int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
541int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
542void tcp_retransmit_timer(struct sock *sk);
543void tcp_xmit_retransmit_queue(struct sock *);
544void tcp_simple_retransmit(struct sock *);
545int tcp_trim_head(struct sock *, struct sk_buff *, u32);
546int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
547
548void tcp_send_probe0(struct sock *);
549void tcp_send_partial(struct sock *);
550int tcp_write_wakeup(struct sock *, int mib);
551void tcp_send_fin(struct sock *sk);
552void tcp_send_active_reset(struct sock *sk, gfp_t priority);
553int tcp_send_synack(struct sock *);
554void tcp_push_one(struct sock *, unsigned int mss_now);
555void tcp_send_ack(struct sock *sk);
556void tcp_send_delayed_ack(struct sock *sk);
557void tcp_send_loss_probe(struct sock *sk);
558bool tcp_schedule_loss_probe(struct sock *sk);
559void tcp_skb_collapse_tstamp(struct sk_buff *skb,
560 const struct sk_buff *next_skb);
561
562/* tcp_input.c */
563void tcp_resume_early_retransmit(struct sock *sk);
564void tcp_rearm_rto(struct sock *sk);
565void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
566void tcp_reset(struct sock *sk);
567void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
568void tcp_fin(struct sock *sk);
569
570/* tcp_timer.c */
571void tcp_init_xmit_timers(struct sock *);
572static inline void tcp_clear_xmit_timers(struct sock *sk)
573{
574 inet_csk_clear_xmit_timers(sk);
575}
576
577unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
578unsigned int tcp_current_mss(struct sock *sk);
579
580/* Bound MSS / TSO packet size with the half of the window */
581static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
582{
583 int cutoff;
584
585 /* When peer uses tiny windows, there is no use in packetizing
586 * to sub-MSS pieces for the sake of SWS or making sure there
587 * are enough packets in the pipe for fast recovery.
588 *
589 * On the other hand, for extremely large MSS devices, handling
590 * smaller than MSS windows in this way does make sense.
591 */
592 if (tp->max_window > TCP_MSS_DEFAULT)
593 cutoff = (tp->max_window >> 1);
594 else
595 cutoff = tp->max_window;
596
597 if (cutoff && pktsize > cutoff)
598 return max_t(int, cutoff, 68U - tp->tcp_header_len);
599 else
600 return pktsize;
601}
602
603/* tcp.c */
604void tcp_get_info(struct sock *, struct tcp_info *);
605
606/* Read 'sendfile()'-style from a TCP socket */
607int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
608 sk_read_actor_t recv_actor);
609
610void tcp_initialize_rcv_mss(struct sock *sk);
611
612int tcp_mtu_to_mss(struct sock *sk, int pmtu);
613int tcp_mss_to_mtu(struct sock *sk, int mss);
614void tcp_mtup_init(struct sock *sk);
615void tcp_init_buffer_space(struct sock *sk);
616
617static inline void tcp_bound_rto(const struct sock *sk)
618{
619 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
620 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
621}
622
623static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
624{
625 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
626}
627
628static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
629{
630 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
631 ntohl(TCP_FLAG_ACK) |
632 snd_wnd);
633}
634
635static inline void tcp_fast_path_on(struct tcp_sock *tp)
636{
637 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
638}
639
640static inline void tcp_fast_path_check(struct sock *sk)
641{
642 struct tcp_sock *tp = tcp_sk(sk);
643
644 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
645 tp->rcv_wnd &&
646 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
647 !tp->urg_data)
648 tcp_fast_path_on(tp);
649}
650
651/* Compute the actual rto_min value */
652static inline u32 tcp_rto_min(struct sock *sk)
653{
654 const struct dst_entry *dst = __sk_dst_get(sk);
655 u32 rto_min = TCP_RTO_MIN;
656
657 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
658 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
659 return rto_min;
660}
661
662static inline u32 tcp_rto_min_us(struct sock *sk)
663{
664 return jiffies_to_usecs(tcp_rto_min(sk));
665}
666
667static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
668{
669 return dst_metric_locked(dst, RTAX_CC_ALGO);
670}
671
672/* Minimum RTT in usec. ~0 means not available. */
673static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
674{
675 return minmax_get(&tp->rtt_min);
676}
677
678/* Compute the actual receive window we are currently advertising.
679 * Rcv_nxt can be after the window if our peer push more data
680 * than the offered window.
681 */
682static inline u32 tcp_receive_window(const struct tcp_sock *tp)
683{
684 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
685
686 if (win < 0)
687 win = 0;
688 return (u32) win;
689}
690
691/* Choose a new window, without checks for shrinking, and without
692 * scaling applied to the result. The caller does these things
693 * if necessary. This is a "raw" window selection.
694 */
695u32 __tcp_select_window(struct sock *sk);
696
697void tcp_send_window_probe(struct sock *sk);
698
699/* TCP timestamps are only 32-bits, this causes a slight
700 * complication on 64-bit systems since we store a snapshot
701 * of jiffies in the buffer control blocks below. We decided
702 * to use only the low 32-bits of jiffies and hide the ugly
703 * casts with the following macro.
704 */
705#define tcp_time_stamp ((__u32)(jiffies))
706
707static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
708{
709 return skb->skb_mstamp.stamp_jiffies;
710}
711
712
713#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
714
715#define TCPHDR_FIN 0x01
716#define TCPHDR_SYN 0x02
717#define TCPHDR_RST 0x04
718#define TCPHDR_PSH 0x08
719#define TCPHDR_ACK 0x10
720#define TCPHDR_URG 0x20
721#define TCPHDR_ECE 0x40
722#define TCPHDR_CWR 0x80
723
724#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
725
726/* This is what the send packet queuing engine uses to pass
727 * TCP per-packet control information to the transmission code.
728 * We also store the host-order sequence numbers in here too.
729 * This is 44 bytes if IPV6 is enabled.
730 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
731 */
732struct tcp_skb_cb {
733 __u32 seq; /* Starting sequence number */
734 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
735 union {
736 /* Note : tcp_tw_isn is used in input path only
737 * (isn chosen by tcp_timewait_state_process())
738 *
739 * tcp_gso_segs/size are used in write queue only,
740 * cf tcp_skb_pcount()/tcp_skb_mss()
741 */
742 __u32 tcp_tw_isn;
743 struct {
744 u16 tcp_gso_segs;
745 u16 tcp_gso_size;
746 };
747 };
748 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
749
750 __u8 sacked; /* State flags for SACK/FACK. */
751#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
752#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
753#define TCPCB_LOST 0x04 /* SKB is lost */
754#define TCPCB_TAGBITS 0x07 /* All tag bits */
755#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
756#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
757#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
758 TCPCB_REPAIRED)
759
760 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
761 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
762 eor:1, /* Is skb MSG_EOR marked? */
763 unused:6;
764 __u32 ack_seq; /* Sequence number ACK'd */
765 union {
766 struct {
767 /* There is space for up to 24 bytes */
768 __u32 in_flight:30,/* Bytes in flight at transmit */
769 is_app_limited:1, /* cwnd not fully used? */
770 unused:1;
771 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
772 __u32 delivered;
773 /* start of send pipeline phase */
774 struct skb_mstamp first_tx_mstamp;
775 /* when we reached the "delivered" count */
776 struct skb_mstamp delivered_mstamp;
777 } tx; /* only used for outgoing skbs */
778 union {
779 struct inet_skb_parm h4;
780#if IS_ENABLED(CONFIG_IPV6)
781 struct inet6_skb_parm h6;
782#endif
783 } header; /* For incoming skbs */
784 };
785};
786
787#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
788
789
790#if IS_ENABLED(CONFIG_IPV6)
791/* This is the variant of inet6_iif() that must be used by TCP,
792 * as TCP moves IP6CB into a different location in skb->cb[]
793 */
794static inline int tcp_v6_iif(const struct sk_buff *skb)
795{
796 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
797
798 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
799}
800#endif
801
802/* TCP_SKB_CB reference means this can not be used from early demux */
803static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
804{
805#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
806 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
807 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
808 return true;
809#endif
810 return false;
811}
812
813/* Due to TSO, an SKB can be composed of multiple actual
814 * packets. To keep these tracked properly, we use this.
815 */
816static inline int tcp_skb_pcount(const struct sk_buff *skb)
817{
818 return TCP_SKB_CB(skb)->tcp_gso_segs;
819}
820
821static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
822{
823 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
824}
825
826static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
827{
828 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
829}
830
831/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
832static inline int tcp_skb_mss(const struct sk_buff *skb)
833{
834 return TCP_SKB_CB(skb)->tcp_gso_size;
835}
836
837static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
838{
839 return likely(!TCP_SKB_CB(skb)->eor);
840}
841
842/* Events passed to congestion control interface */
843enum tcp_ca_event {
844 CA_EVENT_TX_START, /* first transmit when no packets in flight */
845 CA_EVENT_CWND_RESTART, /* congestion window restart */
846 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
847 CA_EVENT_LOSS, /* loss timeout */
848 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
849 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
850 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
851 CA_EVENT_NON_DELAYED_ACK,
852};
853
854/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
855enum tcp_ca_ack_event_flags {
856 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
857 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
858 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
859};
860
861/*
862 * Interface for adding new TCP congestion control handlers
863 */
864#define TCP_CA_NAME_MAX 16
865#define TCP_CA_MAX 128
866#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
867
868#define TCP_CA_UNSPEC 0
869
870/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
871#define TCP_CONG_NON_RESTRICTED 0x1
872/* Requires ECN/ECT set on all packets */
873#define TCP_CONG_NEEDS_ECN 0x2
874
875union tcp_cc_info;
876
877struct ack_sample {
878 u32 pkts_acked;
879 s32 rtt_us;
880 u32 in_flight;
881};
882
883/* A rate sample measures the number of (original/retransmitted) data
884 * packets delivered "delivered" over an interval of time "interval_us".
885 * The tcp_rate.c code fills in the rate sample, and congestion
886 * control modules that define a cong_control function to run at the end
887 * of ACK processing can optionally chose to consult this sample when
888 * setting cwnd and pacing rate.
889 * A sample is invalid if "delivered" or "interval_us" is negative.
890 */
891struct rate_sample {
892 struct skb_mstamp prior_mstamp; /* starting timestamp for interval */
893 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
894 s32 delivered; /* number of packets delivered over interval */
895 long interval_us; /* time for tp->delivered to incr "delivered" */
896 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
897 int losses; /* number of packets marked lost upon ACK */
898 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
899 u32 prior_in_flight; /* in flight before this ACK */
900 bool is_app_limited; /* is sample from packet with bubble in pipe? */
901 bool is_retrans; /* is sample from retransmission? */
902};
903
904struct tcp_congestion_ops {
905 struct list_head list;
906 u32 key;
907 u32 flags;
908
909 /* initialize private data (optional) */
910 void (*init)(struct sock *sk);
911 /* cleanup private data (optional) */
912 void (*release)(struct sock *sk);
913
914 /* return slow start threshold (required) */
915 u32 (*ssthresh)(struct sock *sk);
916 /* do new cwnd calculation (required) */
917 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
918 /* call before changing ca_state (optional) */
919 void (*set_state)(struct sock *sk, u8 new_state);
920 /* call when cwnd event occurs (optional) */
921 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
922 /* call when ack arrives (optional) */
923 void (*in_ack_event)(struct sock *sk, u32 flags);
924 /* new value of cwnd after loss (optional) */
925 u32 (*undo_cwnd)(struct sock *sk);
926 /* hook for packet ack accounting (optional) */
927 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
928 /* suggest number of segments for each skb to transmit (optional) */
929 u32 (*tso_segs_goal)(struct sock *sk);
930 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
931 u32 (*sndbuf_expand)(struct sock *sk);
932 /* call when packets are delivered to update cwnd and pacing rate,
933 * after all the ca_state processing. (optional)
934 */
935 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
936 /* get info for inet_diag (optional) */
937 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
938 union tcp_cc_info *info);
939
940 char name[TCP_CA_NAME_MAX];
941 struct module *owner;
942};
943
944int tcp_register_congestion_control(struct tcp_congestion_ops *type);
945void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
946
947void tcp_assign_congestion_control(struct sock *sk);
948void tcp_init_congestion_control(struct sock *sk);
949void tcp_cleanup_congestion_control(struct sock *sk);
950int tcp_set_default_congestion_control(const char *name);
951void tcp_get_default_congestion_control(char *name);
952void tcp_get_available_congestion_control(char *buf, size_t len);
953void tcp_get_allowed_congestion_control(char *buf, size_t len);
954int tcp_set_allowed_congestion_control(char *allowed);
955int tcp_set_congestion_control(struct sock *sk, const char *name);
956u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
957void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
958
959u32 tcp_reno_ssthresh(struct sock *sk);
960u32 tcp_reno_undo_cwnd(struct sock *sk);
961void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
962extern struct tcp_congestion_ops tcp_reno;
963
964struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
965u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
966#ifdef CONFIG_INET
967char *tcp_ca_get_name_by_key(u32 key, char *buffer);
968#else
969static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
970{
971 return NULL;
972}
973#endif
974
975static inline bool tcp_ca_needs_ecn(const struct sock *sk)
976{
977 const struct inet_connection_sock *icsk = inet_csk(sk);
978
979 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
980}
981
982static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
983{
984 struct inet_connection_sock *icsk = inet_csk(sk);
985
986 if (icsk->icsk_ca_ops->set_state)
987 icsk->icsk_ca_ops->set_state(sk, ca_state);
988 icsk->icsk_ca_state = ca_state;
989}
990
991static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
992{
993 const struct inet_connection_sock *icsk = inet_csk(sk);
994
995 if (icsk->icsk_ca_ops->cwnd_event)
996 icsk->icsk_ca_ops->cwnd_event(sk, event);
997}
998
999/* From tcp_rate.c */
1000void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1001void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1002 struct rate_sample *rs);
1003void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1004 struct skb_mstamp *now, struct rate_sample *rs);
1005void tcp_rate_check_app_limited(struct sock *sk);
1006
1007/* These functions determine how the current flow behaves in respect of SACK
1008 * handling. SACK is negotiated with the peer, and therefore it can vary
1009 * between different flows.
1010 *
1011 * tcp_is_sack - SACK enabled
1012 * tcp_is_reno - No SACK
1013 * tcp_is_fack - FACK enabled, implies SACK enabled
1014 */
1015static inline int tcp_is_sack(const struct tcp_sock *tp)
1016{
1017 return tp->rx_opt.sack_ok;
1018}
1019
1020static inline bool tcp_is_reno(const struct tcp_sock *tp)
1021{
1022 return !tcp_is_sack(tp);
1023}
1024
1025static inline bool tcp_is_fack(const struct tcp_sock *tp)
1026{
1027 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
1028}
1029
1030static inline void tcp_enable_fack(struct tcp_sock *tp)
1031{
1032 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
1033}
1034
1035/* TCP early-retransmit (ER) is similar to but more conservative than
1036 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
1037 */
1038static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
1039{
1040 struct net *net = sock_net((struct sock *)tp);
1041
1042 tp->do_early_retrans = sysctl_tcp_early_retrans &&
1043 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
1044 net->ipv4.sysctl_tcp_reordering == 3;
1045}
1046
1047static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
1048{
1049 tp->do_early_retrans = 0;
1050}
1051
1052static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1053{
1054 return tp->sacked_out + tp->lost_out;
1055}
1056
1057/* This determines how many packets are "in the network" to the best
1058 * of our knowledge. In many cases it is conservative, but where
1059 * detailed information is available from the receiver (via SACK
1060 * blocks etc.) we can make more aggressive calculations.
1061 *
1062 * Use this for decisions involving congestion control, use just
1063 * tp->packets_out to determine if the send queue is empty or not.
1064 *
1065 * Read this equation as:
1066 *
1067 * "Packets sent once on transmission queue" MINUS
1068 * "Packets left network, but not honestly ACKed yet" PLUS
1069 * "Packets fast retransmitted"
1070 */
1071static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1072{
1073 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1074}
1075
1076#define TCP_INFINITE_SSTHRESH 0x7fffffff
1077
1078static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1079{
1080 return tp->snd_cwnd < tp->snd_ssthresh;
1081}
1082
1083static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1084{
1085 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1086}
1087
1088static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1089{
1090 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1091 (1 << inet_csk(sk)->icsk_ca_state);
1092}
1093
1094/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1095 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1096 * ssthresh.
1097 */
1098static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1099{
1100 const struct tcp_sock *tp = tcp_sk(sk);
1101
1102 if (tcp_in_cwnd_reduction(sk))
1103 return tp->snd_ssthresh;
1104 else
1105 return max(tp->snd_ssthresh,
1106 ((tp->snd_cwnd >> 1) +
1107 (tp->snd_cwnd >> 2)));
1108}
1109
1110/* Use define here intentionally to get WARN_ON location shown at the caller */
1111#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1112
1113void tcp_enter_cwr(struct sock *sk);
1114__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1115
1116/* The maximum number of MSS of available cwnd for which TSO defers
1117 * sending if not using sysctl_tcp_tso_win_divisor.
1118 */
1119static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1120{
1121 return 3;
1122}
1123
1124/* Returns end sequence number of the receiver's advertised window */
1125static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1126{
1127 return tp->snd_una + tp->snd_wnd;
1128}
1129
1130/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1131 * flexible approach. The RFC suggests cwnd should not be raised unless
1132 * it was fully used previously. And that's exactly what we do in
1133 * congestion avoidance mode. But in slow start we allow cwnd to grow
1134 * as long as the application has used half the cwnd.
1135 * Example :
1136 * cwnd is 10 (IW10), but application sends 9 frames.
1137 * We allow cwnd to reach 18 when all frames are ACKed.
1138 * This check is safe because it's as aggressive as slow start which already
1139 * risks 100% overshoot. The advantage is that we discourage application to
1140 * either send more filler packets or data to artificially blow up the cwnd
1141 * usage, and allow application-limited process to probe bw more aggressively.
1142 */
1143static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1144{
1145 const struct tcp_sock *tp = tcp_sk(sk);
1146
1147 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1148 if (tcp_in_slow_start(tp))
1149 return tp->snd_cwnd < 2 * tp->max_packets_out;
1150
1151 return tp->is_cwnd_limited;
1152}
1153
1154/* Something is really bad, we could not queue an additional packet,
1155 * because qdisc is full or receiver sent a 0 window.
1156 * We do not want to add fuel to the fire, or abort too early,
1157 * so make sure the timer we arm now is at least 200ms in the future,
1158 * regardless of current icsk_rto value (as it could be ~2ms)
1159 */
1160static inline unsigned long tcp_probe0_base(const struct sock *sk)
1161{
1162 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1163}
1164
1165/* Variant of inet_csk_rto_backoff() used for zero window probes */
1166static inline unsigned long tcp_probe0_when(const struct sock *sk,
1167 unsigned long max_when)
1168{
1169 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1170
1171 return (unsigned long)min_t(u64, when, max_when);
1172}
1173
1174static inline void tcp_check_probe_timer(struct sock *sk)
1175{
1176 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1177 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1178 tcp_probe0_base(sk), TCP_RTO_MAX);
1179}
1180
1181static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1182{
1183 tp->snd_wl1 = seq;
1184}
1185
1186static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1187{
1188 tp->snd_wl1 = seq;
1189}
1190
1191/*
1192 * Calculate(/check) TCP checksum
1193 */
1194static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1195 __be32 daddr, __wsum base)
1196{
1197 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1198}
1199
1200static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1201{
1202 return __skb_checksum_complete(skb);
1203}
1204
1205static inline bool tcp_checksum_complete(struct sk_buff *skb)
1206{
1207 return !skb_csum_unnecessary(skb) &&
1208 __tcp_checksum_complete(skb);
1209}
1210
1211/* Prequeue for VJ style copy to user, combined with checksumming. */
1212
1213static inline void tcp_prequeue_init(struct tcp_sock *tp)
1214{
1215 tp->ucopy.task = NULL;
1216 tp->ucopy.len = 0;
1217 tp->ucopy.memory = 0;
1218 skb_queue_head_init(&tp->ucopy.prequeue);
1219}
1220
1221bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1222bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1223int tcp_filter(struct sock *sk, struct sk_buff *skb);
1224
1225#undef STATE_TRACE
1226
1227#ifdef STATE_TRACE
1228static const char *statename[]={
1229 "Unused","Established","Syn Sent","Syn Recv",
1230 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1231 "Close Wait","Last ACK","Listen","Closing"
1232};
1233#endif
1234void tcp_set_state(struct sock *sk, int state);
1235
1236void tcp_done(struct sock *sk);
1237
1238int tcp_abort(struct sock *sk, int err);
1239
1240static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1241{
1242 rx_opt->dsack = 0;
1243 rx_opt->num_sacks = 0;
1244}
1245
1246u32 tcp_default_init_rwnd(u32 mss);
1247void tcp_cwnd_restart(struct sock *sk, s32 delta);
1248
1249static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1250{
1251 struct tcp_sock *tp = tcp_sk(sk);
1252 s32 delta;
1253
1254 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out)
1255 return;
1256 delta = tcp_time_stamp - tp->lsndtime;
1257 if (delta > inet_csk(sk)->icsk_rto)
1258 tcp_cwnd_restart(sk, delta);
1259}
1260
1261/* Determine a window scaling and initial window to offer. */
1262void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1263 __u32 *window_clamp, int wscale_ok,
1264 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1265
1266static inline int tcp_win_from_space(int space)
1267{
1268 return sysctl_tcp_adv_win_scale<=0 ?
1269 (space>>(-sysctl_tcp_adv_win_scale)) :
1270 space - (space>>sysctl_tcp_adv_win_scale);
1271}
1272
1273/* Note: caller must be prepared to deal with negative returns */
1274static inline int tcp_space(const struct sock *sk)
1275{
1276 return tcp_win_from_space(sk->sk_rcvbuf -
1277 atomic_read(&sk->sk_rmem_alloc));
1278}
1279
1280static inline int tcp_full_space(const struct sock *sk)
1281{
1282 return tcp_win_from_space(sk->sk_rcvbuf);
1283}
1284
1285extern void tcp_openreq_init_rwin(struct request_sock *req,
1286 const struct sock *sk_listener,
1287 const struct dst_entry *dst);
1288
1289void tcp_enter_memory_pressure(struct sock *sk);
1290
1291static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1292{
1293 struct net *net = sock_net((struct sock *)tp);
1294
1295 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1296}
1297
1298static inline int keepalive_time_when(const struct tcp_sock *tp)
1299{
1300 struct net *net = sock_net((struct sock *)tp);
1301
1302 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1303}
1304
1305static inline int keepalive_probes(const struct tcp_sock *tp)
1306{
1307 struct net *net = sock_net((struct sock *)tp);
1308
1309 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1310}
1311
1312static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1313{
1314 const struct inet_connection_sock *icsk = &tp->inet_conn;
1315
1316 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1317 tcp_time_stamp - tp->rcv_tstamp);
1318}
1319
1320static inline int tcp_fin_time(const struct sock *sk)
1321{
1322 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1323 const int rto = inet_csk(sk)->icsk_rto;
1324
1325 if (fin_timeout < (rto << 2) - (rto >> 1))
1326 fin_timeout = (rto << 2) - (rto >> 1);
1327
1328 return fin_timeout;
1329}
1330
1331static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1332 int paws_win)
1333{
1334 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1335 return true;
1336 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1337 return true;
1338 /*
1339 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1340 * then following tcp messages have valid values. Ignore 0 value,
1341 * or else 'negative' tsval might forbid us to accept their packets.
1342 */
1343 if (!rx_opt->ts_recent)
1344 return true;
1345 return false;
1346}
1347
1348static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1349 int rst)
1350{
1351 if (tcp_paws_check(rx_opt, 0))
1352 return false;
1353
1354 /* RST segments are not recommended to carry timestamp,
1355 and, if they do, it is recommended to ignore PAWS because
1356 "their cleanup function should take precedence over timestamps."
1357 Certainly, it is mistake. It is necessary to understand the reasons
1358 of this constraint to relax it: if peer reboots, clock may go
1359 out-of-sync and half-open connections will not be reset.
1360 Actually, the problem would be not existing if all
1361 the implementations followed draft about maintaining clock
1362 via reboots. Linux-2.2 DOES NOT!
1363
1364 However, we can relax time bounds for RST segments to MSL.
1365 */
1366 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1367 return false;
1368 return true;
1369}
1370
1371bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1372 int mib_idx, u32 *last_oow_ack_time);
1373
1374static inline void tcp_mib_init(struct net *net)
1375{
1376 /* See RFC 2012 */
1377 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1378 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1379 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1380 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1381}
1382
1383/* from STCP */
1384static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1385{
1386 tp->lost_skb_hint = NULL;
1387}
1388
1389static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1390{
1391 tcp_clear_retrans_hints_partial(tp);
1392 tp->retransmit_skb_hint = NULL;
1393}
1394
1395union tcp_md5_addr {
1396 struct in_addr a4;
1397#if IS_ENABLED(CONFIG_IPV6)
1398 struct in6_addr a6;
1399#endif
1400};
1401
1402/* - key database */
1403struct tcp_md5sig_key {
1404 struct hlist_node node;
1405 u8 keylen;
1406 u8 family; /* AF_INET or AF_INET6 */
1407 union tcp_md5_addr addr;
1408 u8 key[TCP_MD5SIG_MAXKEYLEN];
1409 struct rcu_head rcu;
1410};
1411
1412/* - sock block */
1413struct tcp_md5sig_info {
1414 struct hlist_head head;
1415 struct rcu_head rcu;
1416};
1417
1418/* - pseudo header */
1419struct tcp4_pseudohdr {
1420 __be32 saddr;
1421 __be32 daddr;
1422 __u8 pad;
1423 __u8 protocol;
1424 __be16 len;
1425};
1426
1427struct tcp6_pseudohdr {
1428 struct in6_addr saddr;
1429 struct in6_addr daddr;
1430 __be32 len;
1431 __be32 protocol; /* including padding */
1432};
1433
1434union tcp_md5sum_block {
1435 struct tcp4_pseudohdr ip4;
1436#if IS_ENABLED(CONFIG_IPV6)
1437 struct tcp6_pseudohdr ip6;
1438#endif
1439};
1440
1441/* - pool: digest algorithm, hash description and scratch buffer */
1442struct tcp_md5sig_pool {
1443 struct ahash_request *md5_req;
1444 void *scratch;
1445};
1446
1447/* - functions */
1448int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1449 const struct sock *sk, const struct sk_buff *skb);
1450int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1451 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1452int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1453 int family);
1454struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1455 const struct sock *addr_sk);
1456
1457#ifdef CONFIG_TCP_MD5SIG
1458struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1459 const union tcp_md5_addr *addr,
1460 int family);
1461#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1462#else
1463static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1464 const union tcp_md5_addr *addr,
1465 int family)
1466{
1467 return NULL;
1468}
1469#define tcp_twsk_md5_key(twsk) NULL
1470#endif
1471
1472bool tcp_alloc_md5sig_pool(void);
1473
1474struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1475static inline void tcp_put_md5sig_pool(void)
1476{
1477 local_bh_enable();
1478}
1479
1480int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1481 unsigned int header_len);
1482int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1483 const struct tcp_md5sig_key *key);
1484
1485/* From tcp_fastopen.c */
1486void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1487 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1488 unsigned long *last_syn_loss);
1489void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1490 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1491 u16 try_exp);
1492struct tcp_fastopen_request {
1493 /* Fast Open cookie. Size 0 means a cookie request */
1494 struct tcp_fastopen_cookie cookie;
1495 struct msghdr *data; /* data in MSG_FASTOPEN */
1496 size_t size;
1497 int copied; /* queued in tcp_connect() */
1498};
1499void tcp_free_fastopen_req(struct tcp_sock *tp);
1500
1501extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1502int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1503void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1504struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1505 struct request_sock *req,
1506 struct tcp_fastopen_cookie *foc,
1507 struct dst_entry *dst);
1508void tcp_fastopen_init_key_once(bool publish);
1509#define TCP_FASTOPEN_KEY_LENGTH 16
1510
1511/* Fastopen key context */
1512struct tcp_fastopen_context {
1513 struct crypto_cipher *tfm;
1514 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1515 struct rcu_head rcu;
1516};
1517
1518/* Latencies incurred by various limits for a sender. They are
1519 * chronograph-like stats that are mutually exclusive.
1520 */
1521enum tcp_chrono {
1522 TCP_CHRONO_UNSPEC,
1523 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1524 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1525 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1526 __TCP_CHRONO_MAX,
1527};
1528
1529void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1530void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1531
1532/* write queue abstraction */
1533static inline void tcp_write_queue_purge(struct sock *sk)
1534{
1535 struct sk_buff *skb;
1536
1537 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1538 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1539 sk_wmem_free_skb(sk, skb);
1540 sk_mem_reclaim(sk);
1541 tcp_clear_all_retrans_hints(tcp_sk(sk));
1542}
1543
1544static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1545{
1546 return skb_peek(&sk->sk_write_queue);
1547}
1548
1549static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1550{
1551 return skb_peek_tail(&sk->sk_write_queue);
1552}
1553
1554static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1555 const struct sk_buff *skb)
1556{
1557 return skb_queue_next(&sk->sk_write_queue, skb);
1558}
1559
1560static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1561 const struct sk_buff *skb)
1562{
1563 return skb_queue_prev(&sk->sk_write_queue, skb);
1564}
1565
1566#define tcp_for_write_queue(skb, sk) \
1567 skb_queue_walk(&(sk)->sk_write_queue, skb)
1568
1569#define tcp_for_write_queue_from(skb, sk) \
1570 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1571
1572#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1573 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1574
1575static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1576{
1577 return sk->sk_send_head;
1578}
1579
1580static inline bool tcp_skb_is_last(const struct sock *sk,
1581 const struct sk_buff *skb)
1582{
1583 return skb_queue_is_last(&sk->sk_write_queue, skb);
1584}
1585
1586static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1587{
1588 if (tcp_skb_is_last(sk, skb))
1589 sk->sk_send_head = NULL;
1590 else
1591 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1592}
1593
1594static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1595{
1596 if (sk->sk_send_head == skb_unlinked) {
1597 sk->sk_send_head = NULL;
1598 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1599 }
1600 if (tcp_sk(sk)->highest_sack == skb_unlinked)
1601 tcp_sk(sk)->highest_sack = NULL;
1602}
1603
1604static inline void tcp_init_send_head(struct sock *sk)
1605{
1606 sk->sk_send_head = NULL;
1607}
1608
1609static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1610{
1611 __skb_queue_tail(&sk->sk_write_queue, skb);
1612}
1613
1614static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1615{
1616 __tcp_add_write_queue_tail(sk, skb);
1617
1618 /* Queue it, remembering where we must start sending. */
1619 if (sk->sk_send_head == NULL) {
1620 sk->sk_send_head = skb;
1621 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1622
1623 if (tcp_sk(sk)->highest_sack == NULL)
1624 tcp_sk(sk)->highest_sack = skb;
1625 }
1626}
1627
1628static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1629{
1630 __skb_queue_head(&sk->sk_write_queue, skb);
1631}
1632
1633/* Insert buff after skb on the write queue of sk. */
1634static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1635 struct sk_buff *buff,
1636 struct sock *sk)
1637{
1638 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1639}
1640
1641/* Insert new before skb on the write queue of sk. */
1642static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1643 struct sk_buff *skb,
1644 struct sock *sk)
1645{
1646 __skb_queue_before(&sk->sk_write_queue, skb, new);
1647
1648 if (sk->sk_send_head == skb)
1649 sk->sk_send_head = new;
1650}
1651
1652static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1653{
1654 __skb_unlink(skb, &sk->sk_write_queue);
1655}
1656
1657static inline bool tcp_write_queue_empty(struct sock *sk)
1658{
1659 return skb_queue_empty(&sk->sk_write_queue);
1660}
1661
1662static inline void tcp_push_pending_frames(struct sock *sk)
1663{
1664 if (tcp_send_head(sk)) {
1665 struct tcp_sock *tp = tcp_sk(sk);
1666
1667 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1668 }
1669}
1670
1671/* Start sequence of the skb just after the highest skb with SACKed
1672 * bit, valid only if sacked_out > 0 or when the caller has ensured
1673 * validity by itself.
1674 */
1675static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1676{
1677 if (!tp->sacked_out)
1678 return tp->snd_una;
1679
1680 if (tp->highest_sack == NULL)
1681 return tp->snd_nxt;
1682
1683 return TCP_SKB_CB(tp->highest_sack)->seq;
1684}
1685
1686static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1687{
1688 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1689 tcp_write_queue_next(sk, skb);
1690}
1691
1692static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1693{
1694 return tcp_sk(sk)->highest_sack;
1695}
1696
1697static inline void tcp_highest_sack_reset(struct sock *sk)
1698{
1699 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1700}
1701
1702/* Called when old skb is about to be deleted (to be combined with new skb) */
1703static inline void tcp_highest_sack_combine(struct sock *sk,
1704 struct sk_buff *old,
1705 struct sk_buff *new)
1706{
1707 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1708 tcp_sk(sk)->highest_sack = new;
1709}
1710
1711/* This helper checks if socket has IP_TRANSPARENT set */
1712static inline bool inet_sk_transparent(const struct sock *sk)
1713{
1714 switch (sk->sk_state) {
1715 case TCP_TIME_WAIT:
1716 return inet_twsk(sk)->tw_transparent;
1717 case TCP_NEW_SYN_RECV:
1718 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1719 }
1720 return inet_sk(sk)->transparent;
1721}
1722
1723/* Determines whether this is a thin stream (which may suffer from
1724 * increased latency). Used to trigger latency-reducing mechanisms.
1725 */
1726static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1727{
1728 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1729}
1730
1731/* /proc */
1732enum tcp_seq_states {
1733 TCP_SEQ_STATE_LISTENING,
1734 TCP_SEQ_STATE_ESTABLISHED,
1735};
1736
1737int tcp_seq_open(struct inode *inode, struct file *file);
1738
1739struct tcp_seq_afinfo {
1740 char *name;
1741 sa_family_t family;
1742 const struct file_operations *seq_fops;
1743 struct seq_operations seq_ops;
1744};
1745
1746struct tcp_iter_state {
1747 struct seq_net_private p;
1748 sa_family_t family;
1749 enum tcp_seq_states state;
1750 struct sock *syn_wait_sk;
1751 int bucket, offset, sbucket, num;
1752 loff_t last_pos;
1753};
1754
1755int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1756void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1757
1758extern struct request_sock_ops tcp_request_sock_ops;
1759extern struct request_sock_ops tcp6_request_sock_ops;
1760
1761void tcp_v4_destroy_sock(struct sock *sk);
1762
1763struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1764 netdev_features_t features);
1765struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1766int tcp_gro_complete(struct sk_buff *skb);
1767
1768void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1769
1770static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1771{
1772 struct net *net = sock_net((struct sock *)tp);
1773 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1774}
1775
1776static inline bool tcp_stream_memory_free(const struct sock *sk)
1777{
1778 const struct tcp_sock *tp = tcp_sk(sk);
1779 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1780
1781 return notsent_bytes < tcp_notsent_lowat(tp);
1782}
1783
1784#ifdef CONFIG_PROC_FS
1785int tcp4_proc_init(void);
1786void tcp4_proc_exit(void);
1787#endif
1788
1789int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1790int tcp_conn_request(struct request_sock_ops *rsk_ops,
1791 const struct tcp_request_sock_ops *af_ops,
1792 struct sock *sk, struct sk_buff *skb);
1793
1794/* TCP af-specific functions */
1795struct tcp_sock_af_ops {
1796#ifdef CONFIG_TCP_MD5SIG
1797 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1798 const struct sock *addr_sk);
1799 int (*calc_md5_hash)(char *location,
1800 const struct tcp_md5sig_key *md5,
1801 const struct sock *sk,
1802 const struct sk_buff *skb);
1803 int (*md5_parse)(struct sock *sk,
1804 char __user *optval,
1805 int optlen);
1806#endif
1807};
1808
1809struct tcp_request_sock_ops {
1810 u16 mss_clamp;
1811#ifdef CONFIG_TCP_MD5SIG
1812 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1813 const struct sock *addr_sk);
1814 int (*calc_md5_hash) (char *location,
1815 const struct tcp_md5sig_key *md5,
1816 const struct sock *sk,
1817 const struct sk_buff *skb);
1818#endif
1819 void (*init_req)(struct request_sock *req,
1820 const struct sock *sk_listener,
1821 struct sk_buff *skb);
1822#ifdef CONFIG_SYN_COOKIES
1823 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1824 __u16 *mss);
1825#endif
1826 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1827 const struct request_sock *req,
1828 bool *strict);
1829 __u32 (*init_seq)(const struct sk_buff *skb, u32 *tsoff);
1830 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1831 struct flowi *fl, struct request_sock *req,
1832 struct tcp_fastopen_cookie *foc,
1833 enum tcp_synack_type synack_type);
1834};
1835
1836#ifdef CONFIG_SYN_COOKIES
1837static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1838 const struct sock *sk, struct sk_buff *skb,
1839 __u16 *mss)
1840{
1841 tcp_synq_overflow(sk);
1842 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1843 return ops->cookie_init_seq(skb, mss);
1844}
1845#else
1846static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1847 const struct sock *sk, struct sk_buff *skb,
1848 __u16 *mss)
1849{
1850 return 0;
1851}
1852#endif
1853
1854int tcpv4_offload_init(void);
1855
1856void tcp_v4_init(void);
1857void tcp_init(void);
1858
1859/* tcp_recovery.c */
1860
1861/* Flags to enable various loss recovery features. See below */
1862extern int sysctl_tcp_recovery;
1863
1864/* Use TCP RACK to detect (some) tail and retransmit losses */
1865#define TCP_RACK_LOST_RETRANS 0x1
1866
1867extern int tcp_rack_mark_lost(struct sock *sk);
1868
1869extern void tcp_rack_advance(struct tcp_sock *tp,
1870 const struct skb_mstamp *xmit_time, u8 sacked);
1871
1872/*
1873 * Save and compile IPv4 options, return a pointer to it
1874 */
1875static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
1876{
1877 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1878 struct ip_options_rcu *dopt = NULL;
1879
1880 if (opt->optlen) {
1881 int opt_size = sizeof(*dopt) + opt->optlen;
1882
1883 dopt = kmalloc(opt_size, GFP_ATOMIC);
1884 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
1885 kfree(dopt);
1886 dopt = NULL;
1887 }
1888 }
1889 return dopt;
1890}
1891
1892/* locally generated TCP pure ACKs have skb->truesize == 2
1893 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1894 * This is much faster than dissecting the packet to find out.
1895 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1896 */
1897static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1898{
1899 return skb->truesize == 2;
1900}
1901
1902static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1903{
1904 skb->truesize = 2;
1905}
1906
1907static inline int tcp_inq(struct sock *sk)
1908{
1909 struct tcp_sock *tp = tcp_sk(sk);
1910 int answ;
1911
1912 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1913 answ = 0;
1914 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1915 !tp->urg_data ||
1916 before(tp->urg_seq, tp->copied_seq) ||
1917 !before(tp->urg_seq, tp->rcv_nxt)) {
1918
1919 answ = tp->rcv_nxt - tp->copied_seq;
1920
1921 /* Subtract 1, if FIN was received */
1922 if (answ && sock_flag(sk, SOCK_DONE))
1923 answ--;
1924 } else {
1925 answ = tp->urg_seq - tp->copied_seq;
1926 }
1927
1928 return answ;
1929}
1930
1931int tcp_peek_len(struct socket *sock);
1932
1933static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1934{
1935 u16 segs_in;
1936
1937 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1938 tp->segs_in += segs_in;
1939 if (skb->len > tcp_hdrlen(skb))
1940 tp->data_segs_in += segs_in;
1941}
1942
1943/*
1944 * TCP listen path runs lockless.
1945 * We forced "struct sock" to be const qualified to make sure
1946 * we don't modify one of its field by mistake.
1947 * Here, we increment sk_drops which is an atomic_t, so we can safely
1948 * make sock writable again.
1949 */
1950static inline void tcp_listendrop(const struct sock *sk)
1951{
1952 atomic_inc(&((struct sock *)sk)->sk_drops);
1953 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
1954}
1955
1956#endif /* _TCP_H */