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1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define FASTRETRANS_DEBUG 1
22
23#include <linux/list.h>
24#include <linux/tcp.h>
25#include <linux/slab.h>
26#include <linux/cache.h>
27#include <linux/percpu.h>
28#include <linux/skbuff.h>
29#include <linux/dmaengine.h>
30#include <linux/crypto.h>
31#include <linux/cryptohash.h>
32#include <linux/kref.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;
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 int sysctl_tcp_wmem[3];
234extern int sysctl_tcp_rmem[3];
235extern int sysctl_tcp_app_win;
236extern int sysctl_tcp_adv_win_scale;
237extern int sysctl_tcp_tw_reuse;
238extern int sysctl_tcp_frto;
239extern int sysctl_tcp_frto_response;
240extern int sysctl_tcp_low_latency;
241extern int sysctl_tcp_dma_copybreak;
242extern int sysctl_tcp_nometrics_save;
243extern int sysctl_tcp_moderate_rcvbuf;
244extern int sysctl_tcp_tso_win_divisor;
245extern int sysctl_tcp_abc;
246extern int sysctl_tcp_mtu_probing;
247extern int sysctl_tcp_base_mss;
248extern int sysctl_tcp_workaround_signed_windows;
249extern int sysctl_tcp_slow_start_after_idle;
250extern int sysctl_tcp_max_ssthresh;
251extern int sysctl_tcp_cookie_size;
252extern int sysctl_tcp_thin_linear_timeouts;
253extern int sysctl_tcp_thin_dupack;
254
255extern atomic_long_t tcp_memory_allocated;
256extern struct percpu_counter tcp_sockets_allocated;
257extern int tcp_memory_pressure;
258
259/*
260 * The next routines deal with comparing 32 bit unsigned ints
261 * and worry about wraparound (automatic with unsigned arithmetic).
262 */
263
264static inline int before(__u32 seq1, __u32 seq2)
265{
266 return (__s32)(seq1-seq2) < 0;
267}
268#define after(seq2, seq1) before(seq1, seq2)
269
270/* is s2<=s1<=s3 ? */
271static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
272{
273 return seq3 - seq2 >= seq1 - seq2;
274}
275
276static inline bool tcp_out_of_memory(struct sock *sk)
277{
278 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
279 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
280 return true;
281 return false;
282}
283
284static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
285{
286 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
287 int orphans = percpu_counter_read_positive(ocp);
288
289 if (orphans << shift > sysctl_tcp_max_orphans) {
290 orphans = percpu_counter_sum_positive(ocp);
291 if (orphans << shift > sysctl_tcp_max_orphans)
292 return true;
293 }
294 return false;
295}
296
297extern bool tcp_check_oom(struct sock *sk, int shift);
298
299/* syncookies: remember time of last synqueue overflow */
300static inline void tcp_synq_overflow(struct sock *sk)
301{
302 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
303}
304
305/* syncookies: no recent synqueue overflow on this listening socket? */
306static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
307{
308 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
309 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
310}
311
312extern struct proto tcp_prot;
313
314#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
315#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
316#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
317#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
318#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
319
320extern void tcp_init_mem(struct net *net);
321
322extern void tcp_v4_err(struct sk_buff *skb, u32);
323
324extern void tcp_shutdown (struct sock *sk, int how);
325
326extern int tcp_v4_rcv(struct sk_buff *skb);
327
328extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
329extern void *tcp_v4_tw_get_peer(struct sock *sk);
330extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
331extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
332 size_t size);
333extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
334 size_t size, int flags);
335extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
336extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
337 const struct tcphdr *th, unsigned int len);
338extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
339 const struct tcphdr *th, unsigned int len);
340extern void tcp_rcv_space_adjust(struct sock *sk);
341extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
342extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
343extern void tcp_twsk_destructor(struct sock *sk);
344extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
345 struct pipe_inode_info *pipe, size_t len,
346 unsigned int flags);
347
348static inline void tcp_dec_quickack_mode(struct sock *sk,
349 const unsigned int pkts)
350{
351 struct inet_connection_sock *icsk = inet_csk(sk);
352
353 if (icsk->icsk_ack.quick) {
354 if (pkts >= icsk->icsk_ack.quick) {
355 icsk->icsk_ack.quick = 0;
356 /* Leaving quickack mode we deflate ATO. */
357 icsk->icsk_ack.ato = TCP_ATO_MIN;
358 } else
359 icsk->icsk_ack.quick -= pkts;
360 }
361}
362
363#define TCP_ECN_OK 1
364#define TCP_ECN_QUEUE_CWR 2
365#define TCP_ECN_DEMAND_CWR 4
366#define TCP_ECN_SEEN 8
367
368static __inline__ void
369TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
370{
371 if (sysctl_tcp_ecn && th->ece && th->cwr)
372 inet_rsk(req)->ecn_ok = 1;
373}
374
375enum tcp_tw_status {
376 TCP_TW_SUCCESS = 0,
377 TCP_TW_RST = 1,
378 TCP_TW_ACK = 2,
379 TCP_TW_SYN = 3
380};
381
382
383extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
384 struct sk_buff *skb,
385 const struct tcphdr *th);
386extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
387 struct request_sock *req,
388 struct request_sock **prev);
389extern int tcp_child_process(struct sock *parent, struct sock *child,
390 struct sk_buff *skb);
391extern int tcp_use_frto(struct sock *sk);
392extern void tcp_enter_frto(struct sock *sk);
393extern void tcp_enter_loss(struct sock *sk, int how);
394extern void tcp_clear_retrans(struct tcp_sock *tp);
395extern void tcp_update_metrics(struct sock *sk);
396extern void tcp_close(struct sock *sk, long timeout);
397extern unsigned int tcp_poll(struct file * file, struct socket *sock,
398 struct poll_table_struct *wait);
399extern int tcp_getsockopt(struct sock *sk, int level, int optname,
400 char __user *optval, int __user *optlen);
401extern int tcp_setsockopt(struct sock *sk, int level, int optname,
402 char __user *optval, unsigned int optlen);
403extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
404 char __user *optval, int __user *optlen);
405extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
406 char __user *optval, unsigned int optlen);
407extern void tcp_set_keepalive(struct sock *sk, int val);
408extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
409extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
410 size_t len, int nonblock, int flags, int *addr_len);
411extern void tcp_parse_options(const struct sk_buff *skb,
412 struct tcp_options_received *opt_rx, const u8 **hvpp,
413 int estab);
414extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
415
416/*
417 * TCP v4 functions exported for the inet6 API
418 */
419
420extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
421extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
422extern struct sock * tcp_create_openreq_child(struct sock *sk,
423 struct request_sock *req,
424 struct sk_buff *skb);
425extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
426 struct request_sock *req,
427 struct dst_entry *dst);
428extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
429extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
430 int addr_len);
431extern int tcp_connect(struct sock *sk);
432extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
433 struct request_sock *req,
434 struct request_values *rvp);
435extern int tcp_disconnect(struct sock *sk, int flags);
436
437
438/* From syncookies.c */
439extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
440extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
441 struct ip_options *opt);
442#ifdef CONFIG_SYN_COOKIES
443extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
444 __u16 *mss);
445#else
446static inline __u32 cookie_v4_init_sequence(struct sock *sk,
447 struct sk_buff *skb,
448 __u16 *mss)
449{
450 return 0;
451}
452#endif
453
454extern __u32 cookie_init_timestamp(struct request_sock *req);
455extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
456
457/* From net/ipv6/syncookies.c */
458extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
459#ifdef CONFIG_SYN_COOKIES
460extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
461 __u16 *mss);
462#else
463static inline __u32 cookie_v6_init_sequence(struct sock *sk,
464 struct sk_buff *skb,
465 __u16 *mss)
466{
467 return 0;
468}
469#endif
470/* tcp_output.c */
471
472extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
473 int nonagle);
474extern int tcp_may_send_now(struct sock *sk);
475extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
476extern void tcp_retransmit_timer(struct sock *sk);
477extern void tcp_xmit_retransmit_queue(struct sock *);
478extern void tcp_simple_retransmit(struct sock *);
479extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
480extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
481
482extern void tcp_send_probe0(struct sock *);
483extern void tcp_send_partial(struct sock *);
484extern int tcp_write_wakeup(struct sock *);
485extern void tcp_send_fin(struct sock *sk);
486extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
487extern int tcp_send_synack(struct sock *);
488extern int tcp_syn_flood_action(struct sock *sk,
489 const struct sk_buff *skb,
490 const char *proto);
491extern void tcp_push_one(struct sock *, unsigned int mss_now);
492extern void tcp_send_ack(struct sock *sk);
493extern void tcp_send_delayed_ack(struct sock *sk);
494
495/* tcp_input.c */
496extern void tcp_cwnd_application_limited(struct sock *sk);
497
498/* tcp_timer.c */
499extern void tcp_init_xmit_timers(struct sock *);
500static inline void tcp_clear_xmit_timers(struct sock *sk)
501{
502 inet_csk_clear_xmit_timers(sk);
503}
504
505extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
506extern unsigned int tcp_current_mss(struct sock *sk);
507
508/* Bound MSS / TSO packet size with the half of the window */
509static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
510{
511 int cutoff;
512
513 /* When peer uses tiny windows, there is no use in packetizing
514 * to sub-MSS pieces for the sake of SWS or making sure there
515 * are enough packets in the pipe for fast recovery.
516 *
517 * On the other hand, for extremely large MSS devices, handling
518 * smaller than MSS windows in this way does make sense.
519 */
520 if (tp->max_window >= 512)
521 cutoff = (tp->max_window >> 1);
522 else
523 cutoff = tp->max_window;
524
525 if (cutoff && pktsize > cutoff)
526 return max_t(int, cutoff, 68U - tp->tcp_header_len);
527 else
528 return pktsize;
529}
530
531/* tcp.c */
532extern void tcp_get_info(const struct sock *, struct tcp_info *);
533
534/* Read 'sendfile()'-style from a TCP socket */
535typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
536 unsigned int, size_t);
537extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
538 sk_read_actor_t recv_actor);
539
540extern void tcp_initialize_rcv_mss(struct sock *sk);
541
542extern int tcp_mtu_to_mss(const struct sock *sk, int pmtu);
543extern int tcp_mss_to_mtu(const struct sock *sk, int mss);
544extern void tcp_mtup_init(struct sock *sk);
545extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
546
547static inline void tcp_bound_rto(const struct sock *sk)
548{
549 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
550 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
551}
552
553static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
554{
555 return (tp->srtt >> 3) + tp->rttvar;
556}
557
558static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
559{
560 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
561 ntohl(TCP_FLAG_ACK) |
562 snd_wnd);
563}
564
565static inline void tcp_fast_path_on(struct tcp_sock *tp)
566{
567 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
568}
569
570static inline void tcp_fast_path_check(struct sock *sk)
571{
572 struct tcp_sock *tp = tcp_sk(sk);
573
574 if (skb_queue_empty(&tp->out_of_order_queue) &&
575 tp->rcv_wnd &&
576 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
577 !tp->urg_data)
578 tcp_fast_path_on(tp);
579}
580
581/* Compute the actual rto_min value */
582static inline u32 tcp_rto_min(struct sock *sk)
583{
584 const struct dst_entry *dst = __sk_dst_get(sk);
585 u32 rto_min = TCP_RTO_MIN;
586
587 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
588 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
589 return rto_min;
590}
591
592/* Compute the actual receive window we are currently advertising.
593 * Rcv_nxt can be after the window if our peer push more data
594 * than the offered window.
595 */
596static inline u32 tcp_receive_window(const struct tcp_sock *tp)
597{
598 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
599
600 if (win < 0)
601 win = 0;
602 return (u32) win;
603}
604
605/* Choose a new window, without checks for shrinking, and without
606 * scaling applied to the result. The caller does these things
607 * if necessary. This is a "raw" window selection.
608 */
609extern u32 __tcp_select_window(struct sock *sk);
610
611/* TCP timestamps are only 32-bits, this causes a slight
612 * complication on 64-bit systems since we store a snapshot
613 * of jiffies in the buffer control blocks below. We decided
614 * to use only the low 32-bits of jiffies and hide the ugly
615 * casts with the following macro.
616 */
617#define tcp_time_stamp ((__u32)(jiffies))
618
619#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
620
621#define TCPHDR_FIN 0x01
622#define TCPHDR_SYN 0x02
623#define TCPHDR_RST 0x04
624#define TCPHDR_PSH 0x08
625#define TCPHDR_ACK 0x10
626#define TCPHDR_URG 0x20
627#define TCPHDR_ECE 0x40
628#define TCPHDR_CWR 0x80
629
630/* This is what the send packet queuing engine uses to pass
631 * TCP per-packet control information to the transmission code.
632 * We also store the host-order sequence numbers in here too.
633 * This is 44 bytes if IPV6 is enabled.
634 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
635 */
636struct tcp_skb_cb {
637 union {
638 struct inet_skb_parm h4;
639#if IS_ENABLED(CONFIG_IPV6)
640 struct inet6_skb_parm h6;
641#endif
642 } header; /* For incoming frames */
643 __u32 seq; /* Starting sequence number */
644 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
645 __u32 when; /* used to compute rtt's */
646 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
647 __u8 sacked; /* State flags for SACK/FACK. */
648#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
649#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
650#define TCPCB_LOST 0x04 /* SKB is lost */
651#define TCPCB_TAGBITS 0x07 /* All tag bits */
652 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
653 /* 1 byte hole */
654#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
655#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
656
657 __u32 ack_seq; /* Sequence number ACK'd */
658};
659
660#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
661
662/* Due to TSO, an SKB can be composed of multiple actual
663 * packets. To keep these tracked properly, we use this.
664 */
665static inline int tcp_skb_pcount(const struct sk_buff *skb)
666{
667 return skb_shinfo(skb)->gso_segs;
668}
669
670/* This is valid iff tcp_skb_pcount() > 1. */
671static inline int tcp_skb_mss(const struct sk_buff *skb)
672{
673 return skb_shinfo(skb)->gso_size;
674}
675
676/* Events passed to congestion control interface */
677enum tcp_ca_event {
678 CA_EVENT_TX_START, /* first transmit when no packets in flight */
679 CA_EVENT_CWND_RESTART, /* congestion window restart */
680 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
681 CA_EVENT_FRTO, /* fast recovery timeout */
682 CA_EVENT_LOSS, /* loss timeout */
683 CA_EVENT_FAST_ACK, /* in sequence ack */
684 CA_EVENT_SLOW_ACK, /* other ack */
685};
686
687/*
688 * Interface for adding new TCP congestion control handlers
689 */
690#define TCP_CA_NAME_MAX 16
691#define TCP_CA_MAX 128
692#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
693
694#define TCP_CONG_NON_RESTRICTED 0x1
695#define TCP_CONG_RTT_STAMP 0x2
696
697struct tcp_congestion_ops {
698 struct list_head list;
699 unsigned long flags;
700
701 /* initialize private data (optional) */
702 void (*init)(struct sock *sk);
703 /* cleanup private data (optional) */
704 void (*release)(struct sock *sk);
705
706 /* return slow start threshold (required) */
707 u32 (*ssthresh)(struct sock *sk);
708 /* lower bound for congestion window (optional) */
709 u32 (*min_cwnd)(const struct sock *sk);
710 /* do new cwnd calculation (required) */
711 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
712 /* call before changing ca_state (optional) */
713 void (*set_state)(struct sock *sk, u8 new_state);
714 /* call when cwnd event occurs (optional) */
715 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
716 /* new value of cwnd after loss (optional) */
717 u32 (*undo_cwnd)(struct sock *sk);
718 /* hook for packet ack accounting (optional) */
719 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
720 /* get info for inet_diag (optional) */
721 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
722
723 char name[TCP_CA_NAME_MAX];
724 struct module *owner;
725};
726
727extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
728extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
729
730extern void tcp_init_congestion_control(struct sock *sk);
731extern void tcp_cleanup_congestion_control(struct sock *sk);
732extern int tcp_set_default_congestion_control(const char *name);
733extern void tcp_get_default_congestion_control(char *name);
734extern void tcp_get_available_congestion_control(char *buf, size_t len);
735extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
736extern int tcp_set_allowed_congestion_control(char *allowed);
737extern int tcp_set_congestion_control(struct sock *sk, const char *name);
738extern void tcp_slow_start(struct tcp_sock *tp);
739extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
740
741extern struct tcp_congestion_ops tcp_init_congestion_ops;
742extern u32 tcp_reno_ssthresh(struct sock *sk);
743extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
744extern u32 tcp_reno_min_cwnd(const struct sock *sk);
745extern struct tcp_congestion_ops tcp_reno;
746
747static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
748{
749 struct inet_connection_sock *icsk = inet_csk(sk);
750
751 if (icsk->icsk_ca_ops->set_state)
752 icsk->icsk_ca_ops->set_state(sk, ca_state);
753 icsk->icsk_ca_state = ca_state;
754}
755
756static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
757{
758 const struct inet_connection_sock *icsk = inet_csk(sk);
759
760 if (icsk->icsk_ca_ops->cwnd_event)
761 icsk->icsk_ca_ops->cwnd_event(sk, event);
762}
763
764/* These functions determine how the current flow behaves in respect of SACK
765 * handling. SACK is negotiated with the peer, and therefore it can vary
766 * between different flows.
767 *
768 * tcp_is_sack - SACK enabled
769 * tcp_is_reno - No SACK
770 * tcp_is_fack - FACK enabled, implies SACK enabled
771 */
772static inline int tcp_is_sack(const struct tcp_sock *tp)
773{
774 return tp->rx_opt.sack_ok;
775}
776
777static inline int tcp_is_reno(const struct tcp_sock *tp)
778{
779 return !tcp_is_sack(tp);
780}
781
782static inline int tcp_is_fack(const struct tcp_sock *tp)
783{
784 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
785}
786
787static inline void tcp_enable_fack(struct tcp_sock *tp)
788{
789 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
790}
791
792static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
793{
794 return tp->sacked_out + tp->lost_out;
795}
796
797/* This determines how many packets are "in the network" to the best
798 * of our knowledge. In many cases it is conservative, but where
799 * detailed information is available from the receiver (via SACK
800 * blocks etc.) we can make more aggressive calculations.
801 *
802 * Use this for decisions involving congestion control, use just
803 * tp->packets_out to determine if the send queue is empty or not.
804 *
805 * Read this equation as:
806 *
807 * "Packets sent once on transmission queue" MINUS
808 * "Packets left network, but not honestly ACKed yet" PLUS
809 * "Packets fast retransmitted"
810 */
811static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
812{
813 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
814}
815
816#define TCP_INFINITE_SSTHRESH 0x7fffffff
817
818static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
819{
820 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
821}
822
823/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
824 * The exception is rate halving phase, when cwnd is decreasing towards
825 * ssthresh.
826 */
827static inline __u32 tcp_current_ssthresh(const struct sock *sk)
828{
829 const struct tcp_sock *tp = tcp_sk(sk);
830
831 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
832 return tp->snd_ssthresh;
833 else
834 return max(tp->snd_ssthresh,
835 ((tp->snd_cwnd >> 1) +
836 (tp->snd_cwnd >> 2)));
837}
838
839/* Use define here intentionally to get WARN_ON location shown at the caller */
840#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
841
842extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
843extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
844
845/* The maximum number of MSS of available cwnd for which TSO defers
846 * sending if not using sysctl_tcp_tso_win_divisor.
847 */
848static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
849{
850 return 3;
851}
852
853/* Slow start with delack produces 3 packets of burst, so that
854 * it is safe "de facto". This will be the default - same as
855 * the default reordering threshold - but if reordering increases,
856 * we must be able to allow cwnd to burst at least this much in order
857 * to not pull it back when holes are filled.
858 */
859static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
860{
861 return tp->reordering;
862}
863
864/* Returns end sequence number of the receiver's advertised window */
865static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
866{
867 return tp->snd_una + tp->snd_wnd;
868}
869extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
870
871static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
872 const struct sk_buff *skb)
873{
874 if (skb->len < mss)
875 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
876}
877
878static inline void tcp_check_probe_timer(struct sock *sk)
879{
880 const struct tcp_sock *tp = tcp_sk(sk);
881 const struct inet_connection_sock *icsk = inet_csk(sk);
882
883 if (!tp->packets_out && !icsk->icsk_pending)
884 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
885 icsk->icsk_rto, TCP_RTO_MAX);
886}
887
888static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
889{
890 tp->snd_wl1 = seq;
891}
892
893static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
894{
895 tp->snd_wl1 = seq;
896}
897
898/*
899 * Calculate(/check) TCP checksum
900 */
901static inline __sum16 tcp_v4_check(int len, __be32 saddr,
902 __be32 daddr, __wsum base)
903{
904 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
905}
906
907static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
908{
909 return __skb_checksum_complete(skb);
910}
911
912static inline int tcp_checksum_complete(struct sk_buff *skb)
913{
914 return !skb_csum_unnecessary(skb) &&
915 __tcp_checksum_complete(skb);
916}
917
918/* Prequeue for VJ style copy to user, combined with checksumming. */
919
920static inline void tcp_prequeue_init(struct tcp_sock *tp)
921{
922 tp->ucopy.task = NULL;
923 tp->ucopy.len = 0;
924 tp->ucopy.memory = 0;
925 skb_queue_head_init(&tp->ucopy.prequeue);
926#ifdef CONFIG_NET_DMA
927 tp->ucopy.dma_chan = NULL;
928 tp->ucopy.wakeup = 0;
929 tp->ucopy.pinned_list = NULL;
930 tp->ucopy.dma_cookie = 0;
931#endif
932}
933
934/* Packet is added to VJ-style prequeue for processing in process
935 * context, if a reader task is waiting. Apparently, this exciting
936 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
937 * failed somewhere. Latency? Burstiness? Well, at least now we will
938 * see, why it failed. 8)8) --ANK
939 *
940 * NOTE: is this not too big to inline?
941 */
942static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
943{
944 struct tcp_sock *tp = tcp_sk(sk);
945
946 if (sysctl_tcp_low_latency || !tp->ucopy.task)
947 return 0;
948
949 __skb_queue_tail(&tp->ucopy.prequeue, skb);
950 tp->ucopy.memory += skb->truesize;
951 if (tp->ucopy.memory > sk->sk_rcvbuf) {
952 struct sk_buff *skb1;
953
954 BUG_ON(sock_owned_by_user(sk));
955
956 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
957 sk_backlog_rcv(sk, skb1);
958 NET_INC_STATS_BH(sock_net(sk),
959 LINUX_MIB_TCPPREQUEUEDROPPED);
960 }
961
962 tp->ucopy.memory = 0;
963 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
964 wake_up_interruptible_sync_poll(sk_sleep(sk),
965 POLLIN | POLLRDNORM | POLLRDBAND);
966 if (!inet_csk_ack_scheduled(sk))
967 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
968 (3 * tcp_rto_min(sk)) / 4,
969 TCP_RTO_MAX);
970 }
971 return 1;
972}
973
974
975#undef STATE_TRACE
976
977#ifdef STATE_TRACE
978static const char *statename[]={
979 "Unused","Established","Syn Sent","Syn Recv",
980 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
981 "Close Wait","Last ACK","Listen","Closing"
982};
983#endif
984extern void tcp_set_state(struct sock *sk, int state);
985
986extern void tcp_done(struct sock *sk);
987
988static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
989{
990 rx_opt->dsack = 0;
991 rx_opt->num_sacks = 0;
992}
993
994/* Determine a window scaling and initial window to offer. */
995extern void tcp_select_initial_window(int __space, __u32 mss,
996 __u32 *rcv_wnd, __u32 *window_clamp,
997 int wscale_ok, __u8 *rcv_wscale,
998 __u32 init_rcv_wnd);
999
1000static inline int tcp_win_from_space(int space)
1001{
1002 return sysctl_tcp_adv_win_scale<=0 ?
1003 (space>>(-sysctl_tcp_adv_win_scale)) :
1004 space - (space>>sysctl_tcp_adv_win_scale);
1005}
1006
1007/* Note: caller must be prepared to deal with negative returns */
1008static inline int tcp_space(const struct sock *sk)
1009{
1010 return tcp_win_from_space(sk->sk_rcvbuf -
1011 atomic_read(&sk->sk_rmem_alloc));
1012}
1013
1014static inline int tcp_full_space(const struct sock *sk)
1015{
1016 return tcp_win_from_space(sk->sk_rcvbuf);
1017}
1018
1019static inline void tcp_openreq_init(struct request_sock *req,
1020 struct tcp_options_received *rx_opt,
1021 struct sk_buff *skb)
1022{
1023 struct inet_request_sock *ireq = inet_rsk(req);
1024
1025 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1026 req->cookie_ts = 0;
1027 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1028 req->mss = rx_opt->mss_clamp;
1029 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1030 ireq->tstamp_ok = rx_opt->tstamp_ok;
1031 ireq->sack_ok = rx_opt->sack_ok;
1032 ireq->snd_wscale = rx_opt->snd_wscale;
1033 ireq->wscale_ok = rx_opt->wscale_ok;
1034 ireq->acked = 0;
1035 ireq->ecn_ok = 0;
1036 ireq->rmt_port = tcp_hdr(skb)->source;
1037 ireq->loc_port = tcp_hdr(skb)->dest;
1038}
1039
1040extern void tcp_enter_memory_pressure(struct sock *sk);
1041
1042static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1043{
1044 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1045}
1046
1047static inline int keepalive_time_when(const struct tcp_sock *tp)
1048{
1049 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1050}
1051
1052static inline int keepalive_probes(const struct tcp_sock *tp)
1053{
1054 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1055}
1056
1057static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1058{
1059 const struct inet_connection_sock *icsk = &tp->inet_conn;
1060
1061 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1062 tcp_time_stamp - tp->rcv_tstamp);
1063}
1064
1065static inline int tcp_fin_time(const struct sock *sk)
1066{
1067 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1068 const int rto = inet_csk(sk)->icsk_rto;
1069
1070 if (fin_timeout < (rto << 2) - (rto >> 1))
1071 fin_timeout = (rto << 2) - (rto >> 1);
1072
1073 return fin_timeout;
1074}
1075
1076static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1077 int paws_win)
1078{
1079 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1080 return 1;
1081 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1082 return 1;
1083 /*
1084 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1085 * then following tcp messages have valid values. Ignore 0 value,
1086 * or else 'negative' tsval might forbid us to accept their packets.
1087 */
1088 if (!rx_opt->ts_recent)
1089 return 1;
1090 return 0;
1091}
1092
1093static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1094 int rst)
1095{
1096 if (tcp_paws_check(rx_opt, 0))
1097 return 0;
1098
1099 /* RST segments are not recommended to carry timestamp,
1100 and, if they do, it is recommended to ignore PAWS because
1101 "their cleanup function should take precedence over timestamps."
1102 Certainly, it is mistake. It is necessary to understand the reasons
1103 of this constraint to relax it: if peer reboots, clock may go
1104 out-of-sync and half-open connections will not be reset.
1105 Actually, the problem would be not existing if all
1106 the implementations followed draft about maintaining clock
1107 via reboots. Linux-2.2 DOES NOT!
1108
1109 However, we can relax time bounds for RST segments to MSL.
1110 */
1111 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1112 return 0;
1113 return 1;
1114}
1115
1116static inline void tcp_mib_init(struct net *net)
1117{
1118 /* See RFC 2012 */
1119 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1120 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1121 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1122 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1123}
1124
1125/* from STCP */
1126static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1127{
1128 tp->lost_skb_hint = NULL;
1129 tp->scoreboard_skb_hint = NULL;
1130}
1131
1132static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1133{
1134 tcp_clear_retrans_hints_partial(tp);
1135 tp->retransmit_skb_hint = NULL;
1136}
1137
1138/* MD5 Signature */
1139struct crypto_hash;
1140
1141/* - key database */
1142struct tcp_md5sig_key {
1143 u8 *key;
1144 u8 keylen;
1145};
1146
1147struct tcp4_md5sig_key {
1148 struct tcp_md5sig_key base;
1149 __be32 addr;
1150};
1151
1152struct tcp6_md5sig_key {
1153 struct tcp_md5sig_key base;
1154#if 0
1155 u32 scope_id; /* XXX */
1156#endif
1157 struct in6_addr addr;
1158};
1159
1160/* - sock block */
1161struct tcp_md5sig_info {
1162 struct tcp4_md5sig_key *keys4;
1163#if IS_ENABLED(CONFIG_IPV6)
1164 struct tcp6_md5sig_key *keys6;
1165 u32 entries6;
1166 u32 alloced6;
1167#endif
1168 u32 entries4;
1169 u32 alloced4;
1170};
1171
1172/* - pseudo header */
1173struct tcp4_pseudohdr {
1174 __be32 saddr;
1175 __be32 daddr;
1176 __u8 pad;
1177 __u8 protocol;
1178 __be16 len;
1179};
1180
1181struct tcp6_pseudohdr {
1182 struct in6_addr saddr;
1183 struct in6_addr daddr;
1184 __be32 len;
1185 __be32 protocol; /* including padding */
1186};
1187
1188union tcp_md5sum_block {
1189 struct tcp4_pseudohdr ip4;
1190#if IS_ENABLED(CONFIG_IPV6)
1191 struct tcp6_pseudohdr ip6;
1192#endif
1193};
1194
1195/* - pool: digest algorithm, hash description and scratch buffer */
1196struct tcp_md5sig_pool {
1197 struct hash_desc md5_desc;
1198 union tcp_md5sum_block md5_blk;
1199};
1200
1201/* - functions */
1202extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1203 const struct sock *sk,
1204 const struct request_sock *req,
1205 const struct sk_buff *skb);
1206extern struct tcp_md5sig_key * tcp_v4_md5_lookup(struct sock *sk,
1207 struct sock *addr_sk);
1208extern int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, u8 *newkey,
1209 u8 newkeylen);
1210extern int tcp_v4_md5_do_del(struct sock *sk, __be32 addr);
1211
1212#ifdef CONFIG_TCP_MD5SIG
1213#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \
1214 &(struct tcp_md5sig_key) { \
1215 .key = (twsk)->tw_md5_key, \
1216 .keylen = (twsk)->tw_md5_keylen, \
1217 } : NULL)
1218#else
1219#define tcp_twsk_md5_key(twsk) NULL
1220#endif
1221
1222extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1223extern void tcp_free_md5sig_pool(void);
1224
1225extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1226extern void tcp_put_md5sig_pool(void);
1227
1228extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1229extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1230 unsigned header_len);
1231extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1232 const struct tcp_md5sig_key *key);
1233
1234/* write queue abstraction */
1235static inline void tcp_write_queue_purge(struct sock *sk)
1236{
1237 struct sk_buff *skb;
1238
1239 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1240 sk_wmem_free_skb(sk, skb);
1241 sk_mem_reclaim(sk);
1242 tcp_clear_all_retrans_hints(tcp_sk(sk));
1243}
1244
1245static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1246{
1247 return skb_peek(&sk->sk_write_queue);
1248}
1249
1250static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1251{
1252 return skb_peek_tail(&sk->sk_write_queue);
1253}
1254
1255static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1256 const struct sk_buff *skb)
1257{
1258 return skb_queue_next(&sk->sk_write_queue, skb);
1259}
1260
1261static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1262 const struct sk_buff *skb)
1263{
1264 return skb_queue_prev(&sk->sk_write_queue, skb);
1265}
1266
1267#define tcp_for_write_queue(skb, sk) \
1268 skb_queue_walk(&(sk)->sk_write_queue, skb)
1269
1270#define tcp_for_write_queue_from(skb, sk) \
1271 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1272
1273#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1274 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1275
1276static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1277{
1278 return sk->sk_send_head;
1279}
1280
1281static inline bool tcp_skb_is_last(const struct sock *sk,
1282 const struct sk_buff *skb)
1283{
1284 return skb_queue_is_last(&sk->sk_write_queue, skb);
1285}
1286
1287static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1288{
1289 if (tcp_skb_is_last(sk, skb))
1290 sk->sk_send_head = NULL;
1291 else
1292 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1293}
1294
1295static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1296{
1297 if (sk->sk_send_head == skb_unlinked)
1298 sk->sk_send_head = NULL;
1299}
1300
1301static inline void tcp_init_send_head(struct sock *sk)
1302{
1303 sk->sk_send_head = NULL;
1304}
1305
1306static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1307{
1308 __skb_queue_tail(&sk->sk_write_queue, skb);
1309}
1310
1311static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1312{
1313 __tcp_add_write_queue_tail(sk, skb);
1314
1315 /* Queue it, remembering where we must start sending. */
1316 if (sk->sk_send_head == NULL) {
1317 sk->sk_send_head = skb;
1318
1319 if (tcp_sk(sk)->highest_sack == NULL)
1320 tcp_sk(sk)->highest_sack = skb;
1321 }
1322}
1323
1324static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1325{
1326 __skb_queue_head(&sk->sk_write_queue, skb);
1327}
1328
1329/* Insert buff after skb on the write queue of sk. */
1330static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1331 struct sk_buff *buff,
1332 struct sock *sk)
1333{
1334 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1335}
1336
1337/* Insert new before skb on the write queue of sk. */
1338static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1339 struct sk_buff *skb,
1340 struct sock *sk)
1341{
1342 __skb_queue_before(&sk->sk_write_queue, skb, new);
1343
1344 if (sk->sk_send_head == skb)
1345 sk->sk_send_head = new;
1346}
1347
1348static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1349{
1350 __skb_unlink(skb, &sk->sk_write_queue);
1351}
1352
1353static inline int tcp_write_queue_empty(struct sock *sk)
1354{
1355 return skb_queue_empty(&sk->sk_write_queue);
1356}
1357
1358static inline void tcp_push_pending_frames(struct sock *sk)
1359{
1360 if (tcp_send_head(sk)) {
1361 struct tcp_sock *tp = tcp_sk(sk);
1362
1363 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1364 }
1365}
1366
1367/* Start sequence of the skb just after the highest skb with SACKed
1368 * bit, valid only if sacked_out > 0 or when the caller has ensured
1369 * validity by itself.
1370 */
1371static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1372{
1373 if (!tp->sacked_out)
1374 return tp->snd_una;
1375
1376 if (tp->highest_sack == NULL)
1377 return tp->snd_nxt;
1378
1379 return TCP_SKB_CB(tp->highest_sack)->seq;
1380}
1381
1382static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1383{
1384 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1385 tcp_write_queue_next(sk, skb);
1386}
1387
1388static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1389{
1390 return tcp_sk(sk)->highest_sack;
1391}
1392
1393static inline void tcp_highest_sack_reset(struct sock *sk)
1394{
1395 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1396}
1397
1398/* Called when old skb is about to be deleted (to be combined with new skb) */
1399static inline void tcp_highest_sack_combine(struct sock *sk,
1400 struct sk_buff *old,
1401 struct sk_buff *new)
1402{
1403 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1404 tcp_sk(sk)->highest_sack = new;
1405}
1406
1407/* Determines whether this is a thin stream (which may suffer from
1408 * increased latency). Used to trigger latency-reducing mechanisms.
1409 */
1410static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
1411{
1412 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1413}
1414
1415/* /proc */
1416enum tcp_seq_states {
1417 TCP_SEQ_STATE_LISTENING,
1418 TCP_SEQ_STATE_OPENREQ,
1419 TCP_SEQ_STATE_ESTABLISHED,
1420 TCP_SEQ_STATE_TIME_WAIT,
1421};
1422
1423int tcp_seq_open(struct inode *inode, struct file *file);
1424
1425struct tcp_seq_afinfo {
1426 char *name;
1427 sa_family_t family;
1428 const struct file_operations *seq_fops;
1429 struct seq_operations seq_ops;
1430};
1431
1432struct tcp_iter_state {
1433 struct seq_net_private p;
1434 sa_family_t family;
1435 enum tcp_seq_states state;
1436 struct sock *syn_wait_sk;
1437 int bucket, offset, sbucket, num, uid;
1438 loff_t last_pos;
1439};
1440
1441extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1442extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1443
1444extern struct request_sock_ops tcp_request_sock_ops;
1445extern struct request_sock_ops tcp6_request_sock_ops;
1446
1447extern void tcp_v4_destroy_sock(struct sock *sk);
1448
1449extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1450extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1451 netdev_features_t features);
1452extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1453 struct sk_buff *skb);
1454extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1455 struct sk_buff *skb);
1456extern int tcp_gro_complete(struct sk_buff *skb);
1457extern int tcp4_gro_complete(struct sk_buff *skb);
1458
1459#ifdef CONFIG_PROC_FS
1460extern int tcp4_proc_init(void);
1461extern void tcp4_proc_exit(void);
1462#endif
1463
1464/* TCP af-specific functions */
1465struct tcp_sock_af_ops {
1466#ifdef CONFIG_TCP_MD5SIG
1467 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1468 struct sock *addr_sk);
1469 int (*calc_md5_hash) (char *location,
1470 struct tcp_md5sig_key *md5,
1471 const struct sock *sk,
1472 const struct request_sock *req,
1473 const struct sk_buff *skb);
1474 int (*md5_add) (struct sock *sk,
1475 struct sock *addr_sk,
1476 u8 *newkey,
1477 u8 len);
1478 int (*md5_parse) (struct sock *sk,
1479 char __user *optval,
1480 int optlen);
1481#endif
1482};
1483
1484struct tcp_request_sock_ops {
1485#ifdef CONFIG_TCP_MD5SIG
1486 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1487 struct request_sock *req);
1488 int (*calc_md5_hash) (char *location,
1489 struct tcp_md5sig_key *md5,
1490 const struct sock *sk,
1491 const struct request_sock *req,
1492 const struct sk_buff *skb);
1493#endif
1494};
1495
1496/* Using SHA1 for now, define some constants.
1497 */
1498#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1499#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1500#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1501
1502extern int tcp_cookie_generator(u32 *bakery);
1503
1504/**
1505 * struct tcp_cookie_values - each socket needs extra space for the
1506 * cookies, together with (optional) space for any SYN data.
1507 *
1508 * A tcp_sock contains a pointer to the current value, and this is
1509 * cloned to the tcp_timewait_sock.
1510 *
1511 * @cookie_pair: variable data from the option exchange.
1512 *
1513 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1514 * indicates default (sysctl_tcp_cookie_size).
1515 * After cookie sent, remembers size of cookie.
1516 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1517 *
1518 * @s_data_desired: user specified tcpct_s_data_desired. When the
1519 * constant payload is specified (@s_data_constant),
1520 * holds its length instead.
1521 * Range 0 to TCP_MSS_DESIRED.
1522 *
1523 * @s_data_payload: constant data that is to be included in the
1524 * payload of SYN or SYNACK segments when the
1525 * cookie option is present.
1526 */
1527struct tcp_cookie_values {
1528 struct kref kref;
1529 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1530 u8 cookie_pair_size;
1531 u8 cookie_desired;
1532 u16 s_data_desired:11,
1533 s_data_constant:1,
1534 s_data_in:1,
1535 s_data_out:1,
1536 s_data_unused:2;
1537 u8 s_data_payload[0];
1538};
1539
1540static inline void tcp_cookie_values_release(struct kref *kref)
1541{
1542 kfree(container_of(kref, struct tcp_cookie_values, kref));
1543}
1544
1545/* The length of constant payload data. Note that s_data_desired is
1546 * overloaded, depending on s_data_constant: either the length of constant
1547 * data (returned here) or the limit on variable data.
1548 */
1549static inline int tcp_s_data_size(const struct tcp_sock *tp)
1550{
1551 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1552 ? tp->cookie_values->s_data_desired
1553 : 0;
1554}
1555
1556/**
1557 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1558 *
1559 * As tcp_request_sock has already been extended in other places, the
1560 * only remaining method is to pass stack values along as function
1561 * parameters. These parameters are not needed after sending SYNACK.
1562 *
1563 * @cookie_bakery: cryptographic secret and message workspace.
1564 *
1565 * @cookie_plus: bytes in authenticator/cookie option, copied from
1566 * struct tcp_options_received (above).
1567 */
1568struct tcp_extend_values {
1569 struct request_values rv;
1570 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1571 u8 cookie_plus:6,
1572 cookie_out_never:1,
1573 cookie_in_always:1;
1574};
1575
1576static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1577{
1578 return (struct tcp_extend_values *)rvp;
1579}
1580
1581extern void tcp_v4_init(void);
1582extern void tcp_init(void);
1583
1584#endif /* _TCP_H */