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.
6 * Definitions for the TCP module.
8 * Version: @(#)tcp.h 1.0.5 05/23/93
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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.
21 #define FASTRETRANS_DEBUG 1
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>
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>
42 #include <net/tcp_states.h>
43 #include <net/inet_ecn.h>
46 #include <linux/seq_file.h>
47 #include <linux/memcontrol.h>
49 #include <linux/bpf.h>
50 #include <linux/filter.h>
51 #include <linux/bpf-cgroup.h>
53 extern struct inet_hashinfo tcp_hashinfo;
55 extern struct percpu_counter tcp_orphan_count;
56 void tcp_time_wait(struct sock *sk, int state, int timeo);
58 #define MAX_TCP_HEADER (128 + MAX_HEADER)
59 #define MAX_TCP_OPTION_SPACE 40
62 * Never offer a window over 32767 without using window scaling. Some
63 * poor stacks do signed 16bit maths!
65 #define MAX_TCP_WINDOW 32767U
67 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68 #define TCP_MIN_MSS 88U
70 /* The least MTU to use for probing */
71 #define TCP_BASE_MSS 1024
73 /* probing interval, default to 10 minutes as per RFC4821 */
74 #define TCP_PROBE_INTERVAL 600
76 /* Specify interval when tcp mtu probing will stop */
77 #define TCP_PROBE_THRESHOLD 8
79 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
80 #define TCP_FASTRETRANS_THRESH 3
82 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
83 #define TCP_MAX_QUICKACKS 16U
85 /* Maximal number of window scale according to RFC1323 */
86 #define TCP_MAX_WSCALE 14U
89 #define TCP_URG_VALID 0x0100
90 #define TCP_URG_NOTYET 0x0200
91 #define TCP_URG_READ 0x0400
93 #define TCP_RETR1 3 /*
94 * This is how many retries it does before it
95 * tries to figure out if the gateway is
96 * down. Minimal RFC value is 3; it corresponds
97 * to ~3sec-8min depending on RTO.
100 #define TCP_RETR2 15 /*
101 * This should take at least
102 * 90 minutes to time out.
103 * RFC1122 says that the limit is 100 sec.
104 * 15 is ~13-30min depending on RTO.
107 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
108 * when active opening a connection.
109 * RFC1122 says the minimum retry MUST
110 * be at least 180secs. Nevertheless
111 * this value is corresponding to
112 * 63secs of retransmission with the
113 * current initial RTO.
116 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
117 * when passive opening a connection.
118 * This is corresponding to 31secs of
119 * retransmission with the current
123 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
124 * state, about 60 seconds */
125 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
126 /* BSD style FIN_WAIT2 deadlock breaker.
127 * It used to be 3min, new value is 60sec,
128 * to combine FIN-WAIT-2 timeout with
132 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
134 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
135 #define TCP_ATO_MIN ((unsigned)(HZ/25))
137 #define TCP_DELACK_MIN 4U
138 #define TCP_ATO_MIN 4U
140 #define TCP_RTO_MAX ((unsigned)(120*HZ))
141 #define TCP_RTO_MIN ((unsigned)(HZ/5))
142 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
143 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
144 * used as a fallback RTO for the
145 * initial data transmission if no
146 * valid RTT sample has been acquired,
147 * most likely due to retrans in 3WHS.
150 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
151 * for local resources.
153 #define TCP_REO_TIMEOUT_MIN (2000) /* Min RACK reordering timeout in usec */
155 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
156 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
157 #define TCP_KEEPALIVE_INTVL (75*HZ)
159 #define MAX_TCP_KEEPIDLE 32767
160 #define MAX_TCP_KEEPINTVL 32767
161 #define MAX_TCP_KEEPCNT 127
162 #define MAX_TCP_SYNCNT 127
164 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
166 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
167 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
168 * after this time. It should be equal
169 * (or greater than) TCP_TIMEWAIT_LEN
170 * to provide reliability equal to one
171 * provided by timewait state.
173 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
174 * timestamps. It must be less than
175 * minimal timewait lifetime.
181 #define TCPOPT_NOP 1 /* Padding */
182 #define TCPOPT_EOL 0 /* End of options */
183 #define TCPOPT_MSS 2 /* Segment size negotiating */
184 #define TCPOPT_WINDOW 3 /* Window scaling */
185 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
186 #define TCPOPT_SACK 5 /* SACK Block */
187 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
188 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
189 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
190 #define TCPOPT_EXP 254 /* Experimental */
191 /* Magic number to be after the option value for sharing TCP
192 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
194 #define TCPOPT_FASTOPEN_MAGIC 0xF989
200 #define TCPOLEN_MSS 4
201 #define TCPOLEN_WINDOW 3
202 #define TCPOLEN_SACK_PERM 2
203 #define TCPOLEN_TIMESTAMP 10
204 #define TCPOLEN_MD5SIG 18
205 #define TCPOLEN_FASTOPEN_BASE 2
206 #define TCPOLEN_EXP_FASTOPEN_BASE 4
208 /* But this is what stacks really send out. */
209 #define TCPOLEN_TSTAMP_ALIGNED 12
210 #define TCPOLEN_WSCALE_ALIGNED 4
211 #define TCPOLEN_SACKPERM_ALIGNED 4
212 #define TCPOLEN_SACK_BASE 2
213 #define TCPOLEN_SACK_BASE_ALIGNED 4
214 #define TCPOLEN_SACK_PERBLOCK 8
215 #define TCPOLEN_MD5SIG_ALIGNED 20
216 #define TCPOLEN_MSS_ALIGNED 4
218 /* Flags in tp->nonagle */
219 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
220 #define TCP_NAGLE_CORK 2 /* Socket is corked */
221 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
223 /* TCP thin-stream limits */
224 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
226 /* TCP initial congestion window as per rfc6928 */
227 #define TCP_INIT_CWND 10
229 /* Bit Flags for sysctl_tcp_fastopen */
230 #define TFO_CLIENT_ENABLE 1
231 #define TFO_SERVER_ENABLE 2
232 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
234 /* Accept SYN data w/o any cookie option */
235 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
237 /* Force enable TFO on all listeners, i.e., not requiring the
238 * TCP_FASTOPEN socket option.
240 #define TFO_SERVER_WO_SOCKOPT1 0x400
243 /* sysctl variables for tcp */
244 extern int sysctl_tcp_fastopen;
245 extern int sysctl_tcp_retrans_collapse;
246 extern int sysctl_tcp_stdurg;
247 extern int sysctl_tcp_rfc1337;
248 extern int sysctl_tcp_abort_on_overflow;
249 extern int sysctl_tcp_max_orphans;
250 extern int sysctl_tcp_fack;
251 extern int sysctl_tcp_reordering;
252 extern int sysctl_tcp_max_reordering;
253 extern int sysctl_tcp_dsack;
254 extern long sysctl_tcp_mem[3];
255 extern int sysctl_tcp_wmem[3];
256 extern int sysctl_tcp_rmem[3];
257 extern int sysctl_tcp_app_win;
258 extern int sysctl_tcp_adv_win_scale;
259 extern int sysctl_tcp_frto;
260 extern int sysctl_tcp_low_latency;
261 extern int sysctl_tcp_nometrics_save;
262 extern int sysctl_tcp_moderate_rcvbuf;
263 extern int sysctl_tcp_tso_win_divisor;
264 extern int sysctl_tcp_workaround_signed_windows;
265 extern int sysctl_tcp_slow_start_after_idle;
266 extern int sysctl_tcp_thin_linear_timeouts;
267 extern int sysctl_tcp_thin_dupack;
268 extern int sysctl_tcp_early_retrans;
269 extern int sysctl_tcp_recovery;
270 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
272 extern int sysctl_tcp_limit_output_bytes;
273 extern int sysctl_tcp_challenge_ack_limit;
274 extern int sysctl_tcp_min_tso_segs;
275 extern int sysctl_tcp_min_rtt_wlen;
276 extern int sysctl_tcp_autocorking;
277 extern int sysctl_tcp_invalid_ratelimit;
278 extern int sysctl_tcp_pacing_ss_ratio;
279 extern int sysctl_tcp_pacing_ca_ratio;
281 extern atomic_long_t tcp_memory_allocated;
282 extern struct percpu_counter tcp_sockets_allocated;
283 extern unsigned long tcp_memory_pressure;
285 /* optimized version of sk_under_memory_pressure() for TCP sockets */
286 static inline bool tcp_under_memory_pressure(const struct sock *sk)
288 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
289 mem_cgroup_under_socket_pressure(sk->sk_memcg))
292 return tcp_memory_pressure;
295 * The next routines deal with comparing 32 bit unsigned ints
296 * and worry about wraparound (automatic with unsigned arithmetic).
299 static inline bool before(__u32 seq1, __u32 seq2)
301 return (__s32)(seq1-seq2) < 0;
303 #define after(seq2, seq1) before(seq1, seq2)
305 /* is s2<=s1<=s3 ? */
306 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
308 return seq3 - seq2 >= seq1 - seq2;
311 static inline bool tcp_out_of_memory(struct sock *sk)
313 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
314 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
319 void sk_forced_mem_schedule(struct sock *sk, int size);
321 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
323 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
324 int orphans = percpu_counter_read_positive(ocp);
326 if (orphans << shift > sysctl_tcp_max_orphans) {
327 orphans = percpu_counter_sum_positive(ocp);
328 if (orphans << shift > sysctl_tcp_max_orphans)
334 bool tcp_check_oom(struct sock *sk, int shift);
337 extern struct proto tcp_prot;
339 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
340 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
341 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
342 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
344 void tcp_tasklet_init(void);
346 void tcp_v4_err(struct sk_buff *skb, u32);
348 void tcp_shutdown(struct sock *sk, int how);
350 void tcp_v4_early_demux(struct sk_buff *skb);
351 int tcp_v4_rcv(struct sk_buff *skb);
353 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
354 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
355 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
357 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
358 size_t size, int flags);
359 void tcp_release_cb(struct sock *sk);
360 void tcp_wfree(struct sk_buff *skb);
361 void tcp_write_timer_handler(struct sock *sk);
362 void tcp_delack_timer_handler(struct sock *sk);
363 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
364 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
365 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
366 const struct tcphdr *th, unsigned int len);
367 void tcp_rcv_space_adjust(struct sock *sk);
368 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
369 void tcp_twsk_destructor(struct sock *sk);
370 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
371 struct pipe_inode_info *pipe, size_t len,
374 static inline void tcp_dec_quickack_mode(struct sock *sk,
375 const unsigned int pkts)
377 struct inet_connection_sock *icsk = inet_csk(sk);
379 if (icsk->icsk_ack.quick) {
380 if (pkts >= icsk->icsk_ack.quick) {
381 icsk->icsk_ack.quick = 0;
382 /* Leaving quickack mode we deflate ATO. */
383 icsk->icsk_ack.ato = TCP_ATO_MIN;
385 icsk->icsk_ack.quick -= pkts;
390 #define TCP_ECN_QUEUE_CWR 2
391 #define TCP_ECN_DEMAND_CWR 4
392 #define TCP_ECN_SEEN 8
402 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
404 const struct tcphdr *th);
405 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
406 struct request_sock *req, bool fastopen);
407 int tcp_child_process(struct sock *parent, struct sock *child,
408 struct sk_buff *skb);
409 void tcp_enter_loss(struct sock *sk);
410 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
411 void tcp_clear_retrans(struct tcp_sock *tp);
412 void tcp_update_metrics(struct sock *sk);
413 void tcp_init_metrics(struct sock *sk);
414 void tcp_metrics_init(void);
415 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
416 void tcp_disable_fack(struct tcp_sock *tp);
417 void tcp_close(struct sock *sk, long timeout);
418 void tcp_init_sock(struct sock *sk);
419 unsigned int tcp_poll(struct file *file, struct socket *sock,
420 struct poll_table_struct *wait);
421 int tcp_getsockopt(struct sock *sk, int level, int optname,
422 char __user *optval, int __user *optlen);
423 int tcp_setsockopt(struct sock *sk, int level, int optname,
424 char __user *optval, unsigned int optlen);
425 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
426 char __user *optval, int __user *optlen);
427 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
428 char __user *optval, unsigned int optlen);
429 void tcp_set_keepalive(struct sock *sk, int val);
430 void tcp_syn_ack_timeout(const struct request_sock *req);
431 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
432 int flags, int *addr_len);
433 void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
434 struct tcp_options_received *opt_rx,
435 int estab, struct tcp_fastopen_cookie *foc);
436 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
439 * TCP v4 functions exported for the inet6 API
442 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
443 void tcp_v4_mtu_reduced(struct sock *sk);
444 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
445 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
446 struct sock *tcp_create_openreq_child(const struct sock *sk,
447 struct request_sock *req,
448 struct sk_buff *skb);
449 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
450 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
451 struct request_sock *req,
452 struct dst_entry *dst,
453 struct request_sock *req_unhash,
455 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
456 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
457 int tcp_connect(struct sock *sk);
458 enum tcp_synack_type {
463 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
464 struct request_sock *req,
465 struct tcp_fastopen_cookie *foc,
466 enum tcp_synack_type synack_type);
467 int tcp_disconnect(struct sock *sk, int flags);
469 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
470 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
471 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
473 /* From syncookies.c */
474 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
475 struct request_sock *req,
476 struct dst_entry *dst, u32 tsoff);
477 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
479 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
480 #ifdef CONFIG_SYN_COOKIES
482 /* Syncookies use a monotonic timer which increments every 60 seconds.
483 * This counter is used both as a hash input and partially encoded into
484 * the cookie value. A cookie is only validated further if the delta
485 * between the current counter value and the encoded one is less than this,
486 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
487 * the counter advances immediately after a cookie is generated).
489 #define MAX_SYNCOOKIE_AGE 2
490 #define TCP_SYNCOOKIE_PERIOD (60 * HZ)
491 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
493 /* syncookies: remember time of last synqueue overflow
494 * But do not dirty this field too often (once per second is enough)
495 * It is racy as we do not hold a lock, but race is very minor.
497 static inline void tcp_synq_overflow(const struct sock *sk)
499 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
500 unsigned long now = jiffies;
502 if (time_after(now, last_overflow + HZ))
503 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
506 /* syncookies: no recent synqueue overflow on this listening socket? */
507 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
509 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
511 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
514 static inline u32 tcp_cookie_time(void)
516 u64 val = get_jiffies_64();
518 do_div(val, TCP_SYNCOOKIE_PERIOD);
522 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
524 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
525 u64 cookie_init_timestamp(struct request_sock *req);
526 bool cookie_timestamp_decode(const struct net *net,
527 struct tcp_options_received *opt);
528 bool cookie_ecn_ok(const struct tcp_options_received *opt,
529 const struct net *net, const struct dst_entry *dst);
531 /* From net/ipv6/syncookies.c */
532 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
534 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
536 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
537 const struct tcphdr *th, u16 *mssp);
538 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
542 u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
544 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
546 bool tcp_may_send_now(struct sock *sk);
547 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
548 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
549 void tcp_retransmit_timer(struct sock *sk);
550 void tcp_xmit_retransmit_queue(struct sock *);
551 void tcp_simple_retransmit(struct sock *);
552 void tcp_enter_recovery(struct sock *sk, bool ece_ack);
553 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
554 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
556 void tcp_send_probe0(struct sock *);
557 void tcp_send_partial(struct sock *);
558 int tcp_write_wakeup(struct sock *, int mib);
559 void tcp_send_fin(struct sock *sk);
560 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
561 int tcp_send_synack(struct sock *);
562 void tcp_push_one(struct sock *, unsigned int mss_now);
563 void tcp_send_ack(struct sock *sk);
564 void tcp_send_delayed_ack(struct sock *sk);
565 void tcp_send_loss_probe(struct sock *sk);
566 bool tcp_schedule_loss_probe(struct sock *sk);
567 void tcp_skb_collapse_tstamp(struct sk_buff *skb,
568 const struct sk_buff *next_skb);
571 void tcp_rearm_rto(struct sock *sk);
572 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
573 void tcp_reset(struct sock *sk);
574 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
575 void tcp_fin(struct sock *sk);
578 void tcp_init_xmit_timers(struct sock *);
579 static inline void tcp_clear_xmit_timers(struct sock *sk)
581 hrtimer_cancel(&tcp_sk(sk)->pacing_timer);
582 inet_csk_clear_xmit_timers(sk);
585 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
586 unsigned int tcp_current_mss(struct sock *sk);
588 /* Bound MSS / TSO packet size with the half of the window */
589 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
593 /* When peer uses tiny windows, there is no use in packetizing
594 * to sub-MSS pieces for the sake of SWS or making sure there
595 * are enough packets in the pipe for fast recovery.
597 * On the other hand, for extremely large MSS devices, handling
598 * smaller than MSS windows in this way does make sense.
600 if (tp->max_window > TCP_MSS_DEFAULT)
601 cutoff = (tp->max_window >> 1);
603 cutoff = tp->max_window;
605 if (cutoff && pktsize > cutoff)
606 return max_t(int, cutoff, 68U - tp->tcp_header_len);
612 void tcp_get_info(struct sock *, struct tcp_info *);
614 /* Read 'sendfile()'-style from a TCP socket */
615 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
616 sk_read_actor_t recv_actor);
618 void tcp_initialize_rcv_mss(struct sock *sk);
620 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
621 int tcp_mss_to_mtu(struct sock *sk, int mss);
622 void tcp_mtup_init(struct sock *sk);
623 void tcp_init_buffer_space(struct sock *sk);
625 static inline void tcp_bound_rto(const struct sock *sk)
627 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
628 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
631 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
633 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
636 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
638 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
639 ntohl(TCP_FLAG_ACK) |
643 static inline void tcp_fast_path_on(struct tcp_sock *tp)
645 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
648 static inline void tcp_fast_path_check(struct sock *sk)
650 struct tcp_sock *tp = tcp_sk(sk);
652 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
654 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
656 tcp_fast_path_on(tp);
659 /* Compute the actual rto_min value */
660 static inline u32 tcp_rto_min(struct sock *sk)
662 const struct dst_entry *dst = __sk_dst_get(sk);
663 u32 rto_min = TCP_RTO_MIN;
665 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
666 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
670 static inline u32 tcp_rto_min_us(struct sock *sk)
672 return jiffies_to_usecs(tcp_rto_min(sk));
675 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
677 return dst_metric_locked(dst, RTAX_CC_ALGO);
680 /* Minimum RTT in usec. ~0 means not available. */
681 static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
683 return minmax_get(&tp->rtt_min);
686 /* Compute the actual receive window we are currently advertising.
687 * Rcv_nxt can be after the window if our peer push more data
688 * than the offered window.
690 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
692 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
699 /* Choose a new window, without checks for shrinking, and without
700 * scaling applied to the result. The caller does these things
701 * if necessary. This is a "raw" window selection.
703 u32 __tcp_select_window(struct sock *sk);
705 void tcp_send_window_probe(struct sock *sk);
707 /* TCP uses 32bit jiffies to save some space.
708 * Note that this is different from tcp_time_stamp, which
709 * historically has been the same until linux-4.13.
711 #define tcp_jiffies32 ((u32)jiffies)
714 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
715 * It is no longer tied to jiffies, but to 1 ms clock.
716 * Note: double check if you want to use tcp_jiffies32 instead of this.
718 #define TCP_TS_HZ 1000
720 static inline u64 tcp_clock_ns(void)
722 return local_clock();
725 static inline u64 tcp_clock_us(void)
727 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
730 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
731 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
733 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
736 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
737 static inline u32 tcp_time_stamp_raw(void)
739 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
743 /* Refresh 1us clock of a TCP socket,
744 * ensuring monotically increasing values.
746 static inline void tcp_mstamp_refresh(struct tcp_sock *tp)
748 u64 val = tcp_clock_us();
750 if (val > tp->tcp_mstamp)
751 tp->tcp_mstamp = val;
754 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
756 return max_t(s64, t1 - t0, 0);
759 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
761 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ);
765 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
767 #define TCPHDR_FIN 0x01
768 #define TCPHDR_SYN 0x02
769 #define TCPHDR_RST 0x04
770 #define TCPHDR_PSH 0x08
771 #define TCPHDR_ACK 0x10
772 #define TCPHDR_URG 0x20
773 #define TCPHDR_ECE 0x40
774 #define TCPHDR_CWR 0x80
776 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
778 /* This is what the send packet queuing engine uses to pass
779 * TCP per-packet control information to the transmission code.
780 * We also store the host-order sequence numbers in here too.
781 * This is 44 bytes if IPV6 is enabled.
782 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
785 __u32 seq; /* Starting sequence number */
786 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
788 /* Note : tcp_tw_isn is used in input path only
789 * (isn chosen by tcp_timewait_state_process())
791 * tcp_gso_segs/size are used in write queue only,
792 * cf tcp_skb_pcount()/tcp_skb_mss()
800 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
802 __u8 sacked; /* State flags for SACK/FACK. */
803 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
804 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
805 #define TCPCB_LOST 0x04 /* SKB is lost */
806 #define TCPCB_TAGBITS 0x07 /* All tag bits */
807 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
808 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
809 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
812 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
813 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
814 eor:1, /* Is skb MSG_EOR marked? */
816 __u32 ack_seq; /* Sequence number ACK'd */
819 /* There is space for up to 24 bytes */
820 __u32 in_flight:30,/* Bytes in flight at transmit */
821 is_app_limited:1, /* cwnd not fully used? */
823 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
825 /* start of send pipeline phase */
827 /* when we reached the "delivered" count */
828 u64 delivered_mstamp;
829 } tx; /* only used for outgoing skbs */
831 struct inet_skb_parm h4;
832 #if IS_ENABLED(CONFIG_IPV6)
833 struct inet6_skb_parm h6;
835 } header; /* For incoming skbs */
839 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
842 #if IS_ENABLED(CONFIG_IPV6)
843 /* This is the variant of inet6_iif() that must be used by TCP,
844 * as TCP moves IP6CB into a different location in skb->cb[]
846 static inline int tcp_v6_iif(const struct sk_buff *skb)
848 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
850 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
854 /* TCP_SKB_CB reference means this can not be used from early demux */
855 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
857 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
858 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
859 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
865 /* Due to TSO, an SKB can be composed of multiple actual
866 * packets. To keep these tracked properly, we use this.
868 static inline int tcp_skb_pcount(const struct sk_buff *skb)
870 return TCP_SKB_CB(skb)->tcp_gso_segs;
873 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
875 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
878 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
880 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
883 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
884 static inline int tcp_skb_mss(const struct sk_buff *skb)
886 return TCP_SKB_CB(skb)->tcp_gso_size;
889 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
891 return likely(!TCP_SKB_CB(skb)->eor);
894 /* Events passed to congestion control interface */
896 CA_EVENT_TX_START, /* first transmit when no packets in flight */
897 CA_EVENT_CWND_RESTART, /* congestion window restart */
898 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
899 CA_EVENT_LOSS, /* loss timeout */
900 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
901 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
902 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
903 CA_EVENT_NON_DELAYED_ACK,
906 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
907 enum tcp_ca_ack_event_flags {
908 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
909 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
910 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
914 * Interface for adding new TCP congestion control handlers
916 #define TCP_CA_NAME_MAX 16
917 #define TCP_CA_MAX 128
918 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
920 #define TCP_CA_UNSPEC 0
922 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
923 #define TCP_CONG_NON_RESTRICTED 0x1
924 /* Requires ECN/ECT set on all packets */
925 #define TCP_CONG_NEEDS_ECN 0x2
935 /* A rate sample measures the number of (original/retransmitted) data
936 * packets delivered "delivered" over an interval of time "interval_us".
937 * The tcp_rate.c code fills in the rate sample, and congestion
938 * control modules that define a cong_control function to run at the end
939 * of ACK processing can optionally chose to consult this sample when
940 * setting cwnd and pacing rate.
941 * A sample is invalid if "delivered" or "interval_us" is negative.
944 u64 prior_mstamp; /* starting timestamp for interval */
945 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
946 s32 delivered; /* number of packets delivered over interval */
947 long interval_us; /* time for tp->delivered to incr "delivered" */
948 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
949 int losses; /* number of packets marked lost upon ACK */
950 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
951 u32 prior_in_flight; /* in flight before this ACK */
952 bool is_app_limited; /* is sample from packet with bubble in pipe? */
953 bool is_retrans; /* is sample from retransmission? */
956 struct tcp_congestion_ops {
957 struct list_head list;
961 /* initialize private data (optional) */
962 void (*init)(struct sock *sk);
963 /* cleanup private data (optional) */
964 void (*release)(struct sock *sk);
966 /* return slow start threshold (required) */
967 u32 (*ssthresh)(struct sock *sk);
968 /* do new cwnd calculation (required) */
969 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
970 /* call before changing ca_state (optional) */
971 void (*set_state)(struct sock *sk, u8 new_state);
972 /* call when cwnd event occurs (optional) */
973 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
974 /* call when ack arrives (optional) */
975 void (*in_ack_event)(struct sock *sk, u32 flags);
976 /* new value of cwnd after loss (required) */
977 u32 (*undo_cwnd)(struct sock *sk);
978 /* hook for packet ack accounting (optional) */
979 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
980 /* suggest number of segments for each skb to transmit (optional) */
981 u32 (*tso_segs_goal)(struct sock *sk);
982 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
983 u32 (*sndbuf_expand)(struct sock *sk);
984 /* call when packets are delivered to update cwnd and pacing rate,
985 * after all the ca_state processing. (optional)
987 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
988 /* get info for inet_diag (optional) */
989 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
990 union tcp_cc_info *info);
992 char name[TCP_CA_NAME_MAX];
993 struct module *owner;
996 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
997 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
999 void tcp_assign_congestion_control(struct sock *sk);
1000 void tcp_init_congestion_control(struct sock *sk);
1001 void tcp_cleanup_congestion_control(struct sock *sk);
1002 int tcp_set_default_congestion_control(const char *name);
1003 void tcp_get_default_congestion_control(char *name);
1004 void tcp_get_available_congestion_control(char *buf, size_t len);
1005 void tcp_get_allowed_congestion_control(char *buf, size_t len);
1006 int tcp_set_allowed_congestion_control(char *allowed);
1007 int tcp_set_congestion_control(struct sock *sk, const char *name);
1008 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1009 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1011 u32 tcp_reno_ssthresh(struct sock *sk);
1012 u32 tcp_reno_undo_cwnd(struct sock *sk);
1013 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1014 extern struct tcp_congestion_ops tcp_reno;
1016 struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1017 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
1019 char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1021 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1027 static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1029 const struct inet_connection_sock *icsk = inet_csk(sk);
1031 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1034 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1036 struct inet_connection_sock *icsk = inet_csk(sk);
1038 if (icsk->icsk_ca_ops->set_state)
1039 icsk->icsk_ca_ops->set_state(sk, ca_state);
1040 icsk->icsk_ca_state = ca_state;
1043 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1045 const struct inet_connection_sock *icsk = inet_csk(sk);
1047 if (icsk->icsk_ca_ops->cwnd_event)
1048 icsk->icsk_ca_ops->cwnd_event(sk, event);
1051 /* From tcp_rate.c */
1052 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1053 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1054 struct rate_sample *rs);
1055 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1056 struct rate_sample *rs);
1057 void tcp_rate_check_app_limited(struct sock *sk);
1059 /* These functions determine how the current flow behaves in respect of SACK
1060 * handling. SACK is negotiated with the peer, and therefore it can vary
1061 * between different flows.
1063 * tcp_is_sack - SACK enabled
1064 * tcp_is_reno - No SACK
1065 * tcp_is_fack - FACK enabled, implies SACK enabled
1067 static inline int tcp_is_sack(const struct tcp_sock *tp)
1069 return tp->rx_opt.sack_ok;
1072 static inline bool tcp_is_reno(const struct tcp_sock *tp)
1074 return !tcp_is_sack(tp);
1077 static inline bool tcp_is_fack(const struct tcp_sock *tp)
1079 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
1082 static inline void tcp_enable_fack(struct tcp_sock *tp)
1084 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
1087 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1089 return tp->sacked_out + tp->lost_out;
1092 /* This determines how many packets are "in the network" to the best
1093 * of our knowledge. In many cases it is conservative, but where
1094 * detailed information is available from the receiver (via SACK
1095 * blocks etc.) we can make more aggressive calculations.
1097 * Use this for decisions involving congestion control, use just
1098 * tp->packets_out to determine if the send queue is empty or not.
1100 * Read this equation as:
1102 * "Packets sent once on transmission queue" MINUS
1103 * "Packets left network, but not honestly ACKed yet" PLUS
1104 * "Packets fast retransmitted"
1106 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1108 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1111 #define TCP_INFINITE_SSTHRESH 0x7fffffff
1113 static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1115 return tp->snd_cwnd < tp->snd_ssthresh;
1118 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1120 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1123 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1125 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1126 (1 << inet_csk(sk)->icsk_ca_state);
1129 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1130 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1133 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1135 const struct tcp_sock *tp = tcp_sk(sk);
1137 if (tcp_in_cwnd_reduction(sk))
1138 return tp->snd_ssthresh;
1140 return max(tp->snd_ssthresh,
1141 ((tp->snd_cwnd >> 1) +
1142 (tp->snd_cwnd >> 2)));
1145 /* Use define here intentionally to get WARN_ON location shown at the caller */
1146 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1148 void tcp_enter_cwr(struct sock *sk);
1149 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1151 /* The maximum number of MSS of available cwnd for which TSO defers
1152 * sending if not using sysctl_tcp_tso_win_divisor.
1154 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1159 /* Returns end sequence number of the receiver's advertised window */
1160 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1162 return tp->snd_una + tp->snd_wnd;
1165 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1166 * flexible approach. The RFC suggests cwnd should not be raised unless
1167 * it was fully used previously. And that's exactly what we do in
1168 * congestion avoidance mode. But in slow start we allow cwnd to grow
1169 * as long as the application has used half the cwnd.
1171 * cwnd is 10 (IW10), but application sends 9 frames.
1172 * We allow cwnd to reach 18 when all frames are ACKed.
1173 * This check is safe because it's as aggressive as slow start which already
1174 * risks 100% overshoot. The advantage is that we discourage application to
1175 * either send more filler packets or data to artificially blow up the cwnd
1176 * usage, and allow application-limited process to probe bw more aggressively.
1178 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1180 const struct tcp_sock *tp = tcp_sk(sk);
1182 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1183 if (tcp_in_slow_start(tp))
1184 return tp->snd_cwnd < 2 * tp->max_packets_out;
1186 return tp->is_cwnd_limited;
1189 /* Something is really bad, we could not queue an additional packet,
1190 * because qdisc is full or receiver sent a 0 window.
1191 * We do not want to add fuel to the fire, or abort too early,
1192 * so make sure the timer we arm now is at least 200ms in the future,
1193 * regardless of current icsk_rto value (as it could be ~2ms)
1195 static inline unsigned long tcp_probe0_base(const struct sock *sk)
1197 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1200 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1201 static inline unsigned long tcp_probe0_when(const struct sock *sk,
1202 unsigned long max_when)
1204 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1206 return (unsigned long)min_t(u64, when, max_when);
1209 static inline void tcp_check_probe_timer(struct sock *sk)
1211 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1212 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1213 tcp_probe0_base(sk), TCP_RTO_MAX);
1216 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1221 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1227 * Calculate(/check) TCP checksum
1229 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1230 __be32 daddr, __wsum base)
1232 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1235 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1237 return __skb_checksum_complete(skb);
1240 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1242 return !skb_csum_unnecessary(skb) &&
1243 __tcp_checksum_complete(skb);
1246 /* Prequeue for VJ style copy to user, combined with checksumming. */
1248 static inline void tcp_prequeue_init(struct tcp_sock *tp)
1250 tp->ucopy.task = NULL;
1252 tp->ucopy.memory = 0;
1253 skb_queue_head_init(&tp->ucopy.prequeue);
1256 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1257 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1258 int tcp_filter(struct sock *sk, struct sk_buff *skb);
1263 static const char *statename[]={
1264 "Unused","Established","Syn Sent","Syn Recv",
1265 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1266 "Close Wait","Last ACK","Listen","Closing"
1269 void tcp_set_state(struct sock *sk, int state);
1271 void tcp_done(struct sock *sk);
1273 int tcp_abort(struct sock *sk, int err);
1275 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1278 rx_opt->num_sacks = 0;
1281 u32 tcp_default_init_rwnd(u32 mss);
1282 void tcp_cwnd_restart(struct sock *sk, s32 delta);
1284 static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1286 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1287 struct tcp_sock *tp = tcp_sk(sk);
1290 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1291 ca_ops->cong_control)
1293 delta = tcp_jiffies32 - tp->lsndtime;
1294 if (delta > inet_csk(sk)->icsk_rto)
1295 tcp_cwnd_restart(sk, delta);
1298 /* Determine a window scaling and initial window to offer. */
1299 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1300 __u32 *window_clamp, int wscale_ok,
1301 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1303 static inline int tcp_win_from_space(int space)
1305 int tcp_adv_win_scale = sysctl_tcp_adv_win_scale;
1307 return tcp_adv_win_scale <= 0 ?
1308 (space>>(-tcp_adv_win_scale)) :
1309 space - (space>>tcp_adv_win_scale);
1312 /* Note: caller must be prepared to deal with negative returns */
1313 static inline int tcp_space(const struct sock *sk)
1315 return tcp_win_from_space(sk->sk_rcvbuf -
1316 atomic_read(&sk->sk_rmem_alloc));
1319 static inline int tcp_full_space(const struct sock *sk)
1321 return tcp_win_from_space(sk->sk_rcvbuf);
1324 extern void tcp_openreq_init_rwin(struct request_sock *req,
1325 const struct sock *sk_listener,
1326 const struct dst_entry *dst);
1328 void tcp_enter_memory_pressure(struct sock *sk);
1329 void tcp_leave_memory_pressure(struct sock *sk);
1331 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1333 struct net *net = sock_net((struct sock *)tp);
1335 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1338 static inline int keepalive_time_when(const struct tcp_sock *tp)
1340 struct net *net = sock_net((struct sock *)tp);
1342 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1345 static inline int keepalive_probes(const struct tcp_sock *tp)
1347 struct net *net = sock_net((struct sock *)tp);
1349 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1352 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1354 const struct inet_connection_sock *icsk = &tp->inet_conn;
1356 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1357 tcp_jiffies32 - tp->rcv_tstamp);
1360 static inline int tcp_fin_time(const struct sock *sk)
1362 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1363 const int rto = inet_csk(sk)->icsk_rto;
1365 if (fin_timeout < (rto << 2) - (rto >> 1))
1366 fin_timeout = (rto << 2) - (rto >> 1);
1371 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1374 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1376 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1379 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1380 * then following tcp messages have valid values. Ignore 0 value,
1381 * or else 'negative' tsval might forbid us to accept their packets.
1383 if (!rx_opt->ts_recent)
1388 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1391 if (tcp_paws_check(rx_opt, 0))
1394 /* RST segments are not recommended to carry timestamp,
1395 and, if they do, it is recommended to ignore PAWS because
1396 "their cleanup function should take precedence over timestamps."
1397 Certainly, it is mistake. It is necessary to understand the reasons
1398 of this constraint to relax it: if peer reboots, clock may go
1399 out-of-sync and half-open connections will not be reset.
1400 Actually, the problem would be not existing if all
1401 the implementations followed draft about maintaining clock
1402 via reboots. Linux-2.2 DOES NOT!
1404 However, we can relax time bounds for RST segments to MSL.
1406 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1411 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1412 int mib_idx, u32 *last_oow_ack_time);
1414 static inline void tcp_mib_init(struct net *net)
1417 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1418 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1419 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1420 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1424 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1426 tp->lost_skb_hint = NULL;
1429 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1431 tcp_clear_retrans_hints_partial(tp);
1432 tp->retransmit_skb_hint = NULL;
1435 union tcp_md5_addr {
1437 #if IS_ENABLED(CONFIG_IPV6)
1442 /* - key database */
1443 struct tcp_md5sig_key {
1444 struct hlist_node node;
1446 u8 family; /* AF_INET or AF_INET6 */
1447 union tcp_md5_addr addr;
1449 u8 key[TCP_MD5SIG_MAXKEYLEN];
1450 struct rcu_head rcu;
1454 struct tcp_md5sig_info {
1455 struct hlist_head head;
1456 struct rcu_head rcu;
1459 /* - pseudo header */
1460 struct tcp4_pseudohdr {
1468 struct tcp6_pseudohdr {
1469 struct in6_addr saddr;
1470 struct in6_addr daddr;
1472 __be32 protocol; /* including padding */
1475 union tcp_md5sum_block {
1476 struct tcp4_pseudohdr ip4;
1477 #if IS_ENABLED(CONFIG_IPV6)
1478 struct tcp6_pseudohdr ip6;
1482 /* - pool: digest algorithm, hash description and scratch buffer */
1483 struct tcp_md5sig_pool {
1484 struct ahash_request *md5_req;
1489 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1490 const struct sock *sk, const struct sk_buff *skb);
1491 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1492 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
1494 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1495 int family, u8 prefixlen);
1496 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1497 const struct sock *addr_sk);
1499 #ifdef CONFIG_TCP_MD5SIG
1500 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1501 const union tcp_md5_addr *addr,
1503 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1505 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1506 const union tcp_md5_addr *addr,
1511 #define tcp_twsk_md5_key(twsk) NULL
1514 bool tcp_alloc_md5sig_pool(void);
1516 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1517 static inline void tcp_put_md5sig_pool(void)
1522 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1523 unsigned int header_len);
1524 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1525 const struct tcp_md5sig_key *key);
1527 /* From tcp_fastopen.c */
1528 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1529 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1530 unsigned long *last_syn_loss);
1531 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1532 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1534 struct tcp_fastopen_request {
1535 /* Fast Open cookie. Size 0 means a cookie request */
1536 struct tcp_fastopen_cookie cookie;
1537 struct msghdr *data; /* data in MSG_FASTOPEN */
1539 int copied; /* queued in tcp_connect() */
1541 void tcp_free_fastopen_req(struct tcp_sock *tp);
1543 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1544 int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1545 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1546 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1547 struct request_sock *req,
1548 struct tcp_fastopen_cookie *foc,
1549 struct dst_entry *dst);
1550 void tcp_fastopen_init_key_once(bool publish);
1551 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1552 struct tcp_fastopen_cookie *cookie);
1553 bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1554 #define TCP_FASTOPEN_KEY_LENGTH 16
1556 /* Fastopen key context */
1557 struct tcp_fastopen_context {
1558 struct crypto_cipher *tfm;
1559 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1560 struct rcu_head rcu;
1563 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1564 void tcp_fastopen_active_disable(struct sock *sk);
1565 bool tcp_fastopen_active_should_disable(struct sock *sk);
1566 void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1567 void tcp_fastopen_active_timeout_reset(void);
1569 /* Latencies incurred by various limits for a sender. They are
1570 * chronograph-like stats that are mutually exclusive.
1574 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1575 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1576 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1580 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1581 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1583 /* write queue abstraction */
1584 static inline void tcp_write_queue_purge(struct sock *sk)
1586 struct sk_buff *skb;
1588 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1589 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1590 sk_wmem_free_skb(sk, skb);
1592 tcp_clear_all_retrans_hints(tcp_sk(sk));
1595 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1597 return skb_peek(&sk->sk_write_queue);
1600 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1602 return skb_peek_tail(&sk->sk_write_queue);
1605 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1606 const struct sk_buff *skb)
1608 return skb_queue_next(&sk->sk_write_queue, skb);
1611 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1612 const struct sk_buff *skb)
1614 return skb_queue_prev(&sk->sk_write_queue, skb);
1617 #define tcp_for_write_queue(skb, sk) \
1618 skb_queue_walk(&(sk)->sk_write_queue, skb)
1620 #define tcp_for_write_queue_from(skb, sk) \
1621 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1623 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1624 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1626 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1628 return sk->sk_send_head;
1631 static inline bool tcp_skb_is_last(const struct sock *sk,
1632 const struct sk_buff *skb)
1634 return skb_queue_is_last(&sk->sk_write_queue, skb);
1637 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1639 if (tcp_skb_is_last(sk, skb))
1640 sk->sk_send_head = NULL;
1642 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1645 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1647 if (sk->sk_send_head == skb_unlinked) {
1648 sk->sk_send_head = NULL;
1649 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1651 if (tcp_sk(sk)->highest_sack == skb_unlinked)
1652 tcp_sk(sk)->highest_sack = NULL;
1655 static inline void tcp_init_send_head(struct sock *sk)
1657 sk->sk_send_head = NULL;
1660 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1662 __skb_queue_tail(&sk->sk_write_queue, skb);
1665 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1667 __tcp_add_write_queue_tail(sk, skb);
1669 /* Queue it, remembering where we must start sending. */
1670 if (sk->sk_send_head == NULL) {
1671 sk->sk_send_head = skb;
1672 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1674 if (tcp_sk(sk)->highest_sack == NULL)
1675 tcp_sk(sk)->highest_sack = skb;
1679 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1681 __skb_queue_head(&sk->sk_write_queue, skb);
1684 /* Insert buff after skb on the write queue of sk. */
1685 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1686 struct sk_buff *buff,
1689 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1692 /* Insert new before skb on the write queue of sk. */
1693 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1694 struct sk_buff *skb,
1697 __skb_queue_before(&sk->sk_write_queue, skb, new);
1699 if (sk->sk_send_head == skb)
1700 sk->sk_send_head = new;
1703 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1705 __skb_unlink(skb, &sk->sk_write_queue);
1708 static inline bool tcp_write_queue_empty(struct sock *sk)
1710 return skb_queue_empty(&sk->sk_write_queue);
1713 static inline void tcp_push_pending_frames(struct sock *sk)
1715 if (tcp_send_head(sk)) {
1716 struct tcp_sock *tp = tcp_sk(sk);
1718 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1722 /* Start sequence of the skb just after the highest skb with SACKed
1723 * bit, valid only if sacked_out > 0 or when the caller has ensured
1724 * validity by itself.
1726 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1728 if (!tp->sacked_out)
1731 if (tp->highest_sack == NULL)
1734 return TCP_SKB_CB(tp->highest_sack)->seq;
1737 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1739 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1740 tcp_write_queue_next(sk, skb);
1743 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1745 return tcp_sk(sk)->highest_sack;
1748 static inline void tcp_highest_sack_reset(struct sock *sk)
1750 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1753 /* Called when old skb is about to be deleted (to be combined with new skb) */
1754 static inline void tcp_highest_sack_combine(struct sock *sk,
1755 struct sk_buff *old,
1756 struct sk_buff *new)
1758 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1759 tcp_sk(sk)->highest_sack = new;
1762 /* This helper checks if socket has IP_TRANSPARENT set */
1763 static inline bool inet_sk_transparent(const struct sock *sk)
1765 switch (sk->sk_state) {
1767 return inet_twsk(sk)->tw_transparent;
1768 case TCP_NEW_SYN_RECV:
1769 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1771 return inet_sk(sk)->transparent;
1774 /* Determines whether this is a thin stream (which may suffer from
1775 * increased latency). Used to trigger latency-reducing mechanisms.
1777 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1779 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1783 enum tcp_seq_states {
1784 TCP_SEQ_STATE_LISTENING,
1785 TCP_SEQ_STATE_ESTABLISHED,
1788 int tcp_seq_open(struct inode *inode, struct file *file);
1790 struct tcp_seq_afinfo {
1793 const struct file_operations *seq_fops;
1794 struct seq_operations seq_ops;
1797 struct tcp_iter_state {
1798 struct seq_net_private p;
1800 enum tcp_seq_states state;
1801 struct sock *syn_wait_sk;
1802 int bucket, offset, sbucket, num;
1806 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1807 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1809 extern struct request_sock_ops tcp_request_sock_ops;
1810 extern struct request_sock_ops tcp6_request_sock_ops;
1812 void tcp_v4_destroy_sock(struct sock *sk);
1814 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1815 netdev_features_t features);
1816 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1817 int tcp_gro_complete(struct sk_buff *skb);
1819 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1821 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1823 struct net *net = sock_net((struct sock *)tp);
1824 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1827 static inline bool tcp_stream_memory_free(const struct sock *sk)
1829 const struct tcp_sock *tp = tcp_sk(sk);
1830 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1832 return notsent_bytes < tcp_notsent_lowat(tp);
1835 #ifdef CONFIG_PROC_FS
1836 int tcp4_proc_init(void);
1837 void tcp4_proc_exit(void);
1840 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1841 int tcp_conn_request(struct request_sock_ops *rsk_ops,
1842 const struct tcp_request_sock_ops *af_ops,
1843 struct sock *sk, struct sk_buff *skb);
1845 /* TCP af-specific functions */
1846 struct tcp_sock_af_ops {
1847 #ifdef CONFIG_TCP_MD5SIG
1848 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1849 const struct sock *addr_sk);
1850 int (*calc_md5_hash)(char *location,
1851 const struct tcp_md5sig_key *md5,
1852 const struct sock *sk,
1853 const struct sk_buff *skb);
1854 int (*md5_parse)(struct sock *sk,
1856 char __user *optval,
1861 struct tcp_request_sock_ops {
1863 #ifdef CONFIG_TCP_MD5SIG
1864 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1865 const struct sock *addr_sk);
1866 int (*calc_md5_hash) (char *location,
1867 const struct tcp_md5sig_key *md5,
1868 const struct sock *sk,
1869 const struct sk_buff *skb);
1871 void (*init_req)(struct request_sock *req,
1872 const struct sock *sk_listener,
1873 struct sk_buff *skb);
1874 #ifdef CONFIG_SYN_COOKIES
1875 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1878 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1879 const struct request_sock *req);
1880 u32 (*init_seq)(const struct sk_buff *skb);
1881 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1882 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1883 struct flowi *fl, struct request_sock *req,
1884 struct tcp_fastopen_cookie *foc,
1885 enum tcp_synack_type synack_type);
1888 #ifdef CONFIG_SYN_COOKIES
1889 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1890 const struct sock *sk, struct sk_buff *skb,
1893 tcp_synq_overflow(sk);
1894 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1895 return ops->cookie_init_seq(skb, mss);
1898 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1899 const struct sock *sk, struct sk_buff *skb,
1906 int tcpv4_offload_init(void);
1908 void tcp_v4_init(void);
1909 void tcp_init(void);
1911 /* tcp_recovery.c */
1912 extern void tcp_rack_mark_lost(struct sock *sk);
1913 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
1915 extern void tcp_rack_reo_timeout(struct sock *sk);
1918 * Save and compile IPv4 options, return a pointer to it
1920 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
1922 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1923 struct ip_options_rcu *dopt = NULL;
1926 int opt_size = sizeof(*dopt) + opt->optlen;
1928 dopt = kmalloc(opt_size, GFP_ATOMIC);
1929 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
1937 /* locally generated TCP pure ACKs have skb->truesize == 2
1938 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1939 * This is much faster than dissecting the packet to find out.
1940 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1942 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1944 return skb->truesize == 2;
1947 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1952 static inline int tcp_inq(struct sock *sk)
1954 struct tcp_sock *tp = tcp_sk(sk);
1957 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1959 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1961 before(tp->urg_seq, tp->copied_seq) ||
1962 !before(tp->urg_seq, tp->rcv_nxt)) {
1964 answ = tp->rcv_nxt - tp->copied_seq;
1966 /* Subtract 1, if FIN was received */
1967 if (answ && sock_flag(sk, SOCK_DONE))
1970 answ = tp->urg_seq - tp->copied_seq;
1976 int tcp_peek_len(struct socket *sock);
1978 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1982 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1983 tp->segs_in += segs_in;
1984 if (skb->len > tcp_hdrlen(skb))
1985 tp->data_segs_in += segs_in;
1989 * TCP listen path runs lockless.
1990 * We forced "struct sock" to be const qualified to make sure
1991 * we don't modify one of its field by mistake.
1992 * Here, we increment sk_drops which is an atomic_t, so we can safely
1993 * make sock writable again.
1995 static inline void tcp_listendrop(const struct sock *sk)
1997 atomic_inc(&((struct sock *)sk)->sk_drops);
1998 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2001 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2004 * Interface for adding Upper Level Protocols over TCP
2007 #define TCP_ULP_NAME_MAX 16
2008 #define TCP_ULP_MAX 128
2009 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2011 struct tcp_ulp_ops {
2012 struct list_head list;
2014 /* initialize ulp */
2015 int (*init)(struct sock *sk);
2017 void (*release)(struct sock *sk);
2019 char name[TCP_ULP_NAME_MAX];
2020 struct module *owner;
2022 int tcp_register_ulp(struct tcp_ulp_ops *type);
2023 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2024 int tcp_set_ulp(struct sock *sk, const char *name);
2025 void tcp_get_available_ulp(char *buf, size_t len);
2026 void tcp_cleanup_ulp(struct sock *sk);
2028 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2029 * is < 0, then the BPF op failed (for example if the loaded BPF
2030 * program does not support the chosen operation or there is no BPF
2034 static inline int tcp_call_bpf(struct sock *sk, int op)
2036 struct bpf_sock_ops_kern sock_ops;
2039 if (sk_fullsock(sk))
2040 sock_owned_by_me(sk);
2042 memset(&sock_ops, 0, sizeof(sock_ops));
2046 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2048 ret = sock_ops.reply;
2054 static inline int tcp_call_bpf(struct sock *sk, int op)