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>
48 #include <linux/bpf-cgroup.h>
50 extern struct inet_hashinfo tcp_hashinfo;
52 extern struct percpu_counter tcp_orphan_count;
53 void tcp_time_wait(struct sock *sk, int state, int timeo);
55 #define MAX_TCP_HEADER (128 + MAX_HEADER)
56 #define MAX_TCP_OPTION_SPACE 40
59 * Never offer a window over 32767 without using window scaling. Some
60 * poor stacks do signed 16bit maths!
62 #define MAX_TCP_WINDOW 32767U
64 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
65 #define TCP_MIN_MSS 88U
67 /* The least MTU to use for probing */
68 #define TCP_BASE_MSS 1024
70 /* probing interval, default to 10 minutes as per RFC4821 */
71 #define TCP_PROBE_INTERVAL 600
73 /* Specify interval when tcp mtu probing will stop */
74 #define TCP_PROBE_THRESHOLD 8
76 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
77 #define TCP_FASTRETRANS_THRESH 3
79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
80 #define TCP_MAX_QUICKACKS 16U
82 /* Maximal number of window scale according to RFC1323 */
83 #define TCP_MAX_WSCALE 14U
86 #define TCP_URG_VALID 0x0100
87 #define TCP_URG_NOTYET 0x0200
88 #define TCP_URG_READ 0x0400
90 #define TCP_RETR1 3 /*
91 * This is how many retries it does before it
92 * tries to figure out if the gateway is
93 * down. Minimal RFC value is 3; it corresponds
94 * to ~3sec-8min depending on RTO.
97 #define TCP_RETR2 15 /*
98 * This should take at least
99 * 90 minutes to time out.
100 * RFC1122 says that the limit is 100 sec.
101 * 15 is ~13-30min depending on RTO.
104 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
105 * when active opening a connection.
106 * RFC1122 says the minimum retry MUST
107 * be at least 180secs. Nevertheless
108 * this value is corresponding to
109 * 63secs of retransmission with the
110 * current initial RTO.
113 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
114 * when passive opening a connection.
115 * This is corresponding to 31secs of
116 * retransmission with the current
120 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
121 * state, about 60 seconds */
122 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
123 /* BSD style FIN_WAIT2 deadlock breaker.
124 * It used to be 3min, new value is 60sec,
125 * to combine FIN-WAIT-2 timeout with
129 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
131 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
132 #define TCP_ATO_MIN ((unsigned)(HZ/25))
134 #define TCP_DELACK_MIN 4U
135 #define TCP_ATO_MIN 4U
137 #define TCP_RTO_MAX ((unsigned)(120*HZ))
138 #define TCP_RTO_MIN ((unsigned)(HZ/5))
139 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
140 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
141 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
142 * used as a fallback RTO for the
143 * initial data transmission if no
144 * valid RTT sample has been acquired,
145 * most likely due to retrans in 3WHS.
148 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
149 * for local resources.
151 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
152 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
153 #define TCP_KEEPALIVE_INTVL (75*HZ)
155 #define MAX_TCP_KEEPIDLE 32767
156 #define MAX_TCP_KEEPINTVL 32767
157 #define MAX_TCP_KEEPCNT 127
158 #define MAX_TCP_SYNCNT 127
160 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
162 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
163 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
164 * after this time. It should be equal
165 * (or greater than) TCP_TIMEWAIT_LEN
166 * to provide reliability equal to one
167 * provided by timewait state.
169 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
170 * timestamps. It must be less than
171 * minimal timewait lifetime.
177 #define TCPOPT_NOP 1 /* Padding */
178 #define TCPOPT_EOL 0 /* End of options */
179 #define TCPOPT_MSS 2 /* Segment size negotiating */
180 #define TCPOPT_WINDOW 3 /* Window scaling */
181 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
182 #define TCPOPT_SACK 5 /* SACK Block */
183 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
184 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
185 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
186 #define TCPOPT_EXP 254 /* Experimental */
187 /* Magic number to be after the option value for sharing TCP
188 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
190 #define TCPOPT_FASTOPEN_MAGIC 0xF989
191 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9
197 #define TCPOLEN_MSS 4
198 #define TCPOLEN_WINDOW 3
199 #define TCPOLEN_SACK_PERM 2
200 #define TCPOLEN_TIMESTAMP 10
201 #define TCPOLEN_MD5SIG 18
202 #define TCPOLEN_FASTOPEN_BASE 2
203 #define TCPOLEN_EXP_FASTOPEN_BASE 4
204 #define TCPOLEN_EXP_SMC_BASE 6
206 /* But this is what stacks really send out. */
207 #define TCPOLEN_TSTAMP_ALIGNED 12
208 #define TCPOLEN_WSCALE_ALIGNED 4
209 #define TCPOLEN_SACKPERM_ALIGNED 4
210 #define TCPOLEN_SACK_BASE 2
211 #define TCPOLEN_SACK_BASE_ALIGNED 4
212 #define TCPOLEN_SACK_PERBLOCK 8
213 #define TCPOLEN_MD5SIG_ALIGNED 20
214 #define TCPOLEN_MSS_ALIGNED 4
215 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
217 /* Flags in tp->nonagle */
218 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
219 #define TCP_NAGLE_CORK 2 /* Socket is corked */
220 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
222 /* TCP thin-stream limits */
223 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
225 /* TCP initial congestion window as per rfc6928 */
226 #define TCP_INIT_CWND 10
228 /* Bit Flags for sysctl_tcp_fastopen */
229 #define TFO_CLIENT_ENABLE 1
230 #define TFO_SERVER_ENABLE 2
231 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
233 /* Accept SYN data w/o any cookie option */
234 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
236 /* Force enable TFO on all listeners, i.e., not requiring the
237 * TCP_FASTOPEN socket option.
239 #define TFO_SERVER_WO_SOCKOPT1 0x400
242 /* sysctl variables for tcp */
243 extern int sysctl_tcp_max_orphans;
244 extern long sysctl_tcp_mem[3];
245 extern int sysctl_tcp_wmem[3];
246 extern int sysctl_tcp_rmem[3];
248 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
250 extern atomic_long_t tcp_memory_allocated;
251 extern struct percpu_counter tcp_sockets_allocated;
252 extern unsigned long tcp_memory_pressure;
254 /* optimized version of sk_under_memory_pressure() for TCP sockets */
255 static inline bool tcp_under_memory_pressure(const struct sock *sk)
257 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
258 mem_cgroup_under_socket_pressure(sk->sk_memcg))
261 return tcp_memory_pressure;
264 * The next routines deal with comparing 32 bit unsigned ints
265 * and worry about wraparound (automatic with unsigned arithmetic).
268 static inline bool before(__u32 seq1, __u32 seq2)
270 return (__s32)(seq1-seq2) < 0;
272 #define after(seq2, seq1) before(seq1, seq2)
274 /* is s2<=s1<=s3 ? */
275 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
277 return seq3 - seq2 >= seq1 - seq2;
280 static inline bool tcp_out_of_memory(struct sock *sk)
282 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
283 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
288 void sk_forced_mem_schedule(struct sock *sk, int size);
290 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
292 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
293 int orphans = percpu_counter_read_positive(ocp);
295 if (orphans << shift > sysctl_tcp_max_orphans) {
296 orphans = percpu_counter_sum_positive(ocp);
297 if (orphans << shift > sysctl_tcp_max_orphans)
303 bool tcp_check_oom(struct sock *sk, int shift);
306 extern struct proto tcp_prot;
308 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
309 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
311 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
313 void tcp_tasklet_init(void);
315 void tcp_v4_err(struct sk_buff *skb, u32);
317 void tcp_shutdown(struct sock *sk, int how);
319 int tcp_v4_early_demux(struct sk_buff *skb);
320 int tcp_v4_rcv(struct sk_buff *skb);
322 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
323 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
324 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
325 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
327 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
328 size_t size, int flags);
329 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
330 size_t size, int flags);
331 void tcp_release_cb(struct sock *sk);
332 void tcp_wfree(struct sk_buff *skb);
333 void tcp_write_timer_handler(struct sock *sk);
334 void tcp_delack_timer_handler(struct sock *sk);
335 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
336 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
337 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
338 const struct tcphdr *th);
339 void tcp_rcv_space_adjust(struct sock *sk);
340 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
341 void tcp_twsk_destructor(struct sock *sk);
342 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
343 struct pipe_inode_info *pipe, size_t len,
346 static inline void tcp_dec_quickack_mode(struct sock *sk,
347 const unsigned int pkts)
349 struct inet_connection_sock *icsk = inet_csk(sk);
351 if (icsk->icsk_ack.quick) {
352 if (pkts >= icsk->icsk_ack.quick) {
353 icsk->icsk_ack.quick = 0;
354 /* Leaving quickack mode we deflate ATO. */
355 icsk->icsk_ack.ato = TCP_ATO_MIN;
357 icsk->icsk_ack.quick -= pkts;
362 #define TCP_ECN_QUEUE_CWR 2
363 #define TCP_ECN_DEMAND_CWR 4
364 #define TCP_ECN_SEEN 8
374 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
376 const struct tcphdr *th);
377 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
378 struct request_sock *req, bool fastopen);
379 int tcp_child_process(struct sock *parent, struct sock *child,
380 struct sk_buff *skb);
381 void tcp_enter_loss(struct sock *sk);
382 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
383 void tcp_clear_retrans(struct tcp_sock *tp);
384 void tcp_update_metrics(struct sock *sk);
385 void tcp_init_metrics(struct sock *sk);
386 void tcp_metrics_init(void);
387 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
388 void tcp_disable_fack(struct tcp_sock *tp);
389 void tcp_close(struct sock *sk, long timeout);
390 void tcp_init_sock(struct sock *sk);
391 void tcp_init_transfer(struct sock *sk, int bpf_op);
392 unsigned int tcp_poll(struct file *file, struct socket *sock,
393 struct poll_table_struct *wait);
394 int tcp_getsockopt(struct sock *sk, int level, int optname,
395 char __user *optval, int __user *optlen);
396 int tcp_setsockopt(struct sock *sk, int level, int optname,
397 char __user *optval, unsigned int optlen);
398 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
399 char __user *optval, int __user *optlen);
400 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
401 char __user *optval, unsigned int optlen);
402 void tcp_set_keepalive(struct sock *sk, int val);
403 void tcp_syn_ack_timeout(const struct request_sock *req);
404 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
405 int flags, int *addr_len);
406 void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
407 struct tcp_options_received *opt_rx,
408 int estab, struct tcp_fastopen_cookie *foc);
409 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
412 * TCP v4 functions exported for the inet6 API
415 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
416 void tcp_v4_mtu_reduced(struct sock *sk);
417 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
418 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
419 struct sock *tcp_create_openreq_child(const struct sock *sk,
420 struct request_sock *req,
421 struct sk_buff *skb);
422 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
423 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
424 struct request_sock *req,
425 struct dst_entry *dst,
426 struct request_sock *req_unhash,
428 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
429 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
430 int tcp_connect(struct sock *sk);
431 enum tcp_synack_type {
436 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
437 struct request_sock *req,
438 struct tcp_fastopen_cookie *foc,
439 enum tcp_synack_type synack_type);
440 int tcp_disconnect(struct sock *sk, int flags);
442 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
443 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
444 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
446 /* From syncookies.c */
447 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
448 struct request_sock *req,
449 struct dst_entry *dst, u32 tsoff);
450 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
452 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
453 #ifdef CONFIG_SYN_COOKIES
455 /* Syncookies use a monotonic timer which increments every 60 seconds.
456 * This counter is used both as a hash input and partially encoded into
457 * the cookie value. A cookie is only validated further if the delta
458 * between the current counter value and the encoded one is less than this,
459 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
460 * the counter advances immediately after a cookie is generated).
462 #define MAX_SYNCOOKIE_AGE 2
463 #define TCP_SYNCOOKIE_PERIOD (60 * HZ)
464 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
466 /* syncookies: remember time of last synqueue overflow
467 * But do not dirty this field too often (once per second is enough)
468 * It is racy as we do not hold a lock, but race is very minor.
470 static inline void tcp_synq_overflow(const struct sock *sk)
472 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
473 unsigned long now = jiffies;
475 if (time_after(now, last_overflow + HZ))
476 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
479 /* syncookies: no recent synqueue overflow on this listening socket? */
480 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
482 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
484 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
487 static inline u32 tcp_cookie_time(void)
489 u64 val = get_jiffies_64();
491 do_div(val, TCP_SYNCOOKIE_PERIOD);
495 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
497 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
498 u64 cookie_init_timestamp(struct request_sock *req);
499 bool cookie_timestamp_decode(const struct net *net,
500 struct tcp_options_received *opt);
501 bool cookie_ecn_ok(const struct tcp_options_received *opt,
502 const struct net *net, const struct dst_entry *dst);
504 /* From net/ipv6/syncookies.c */
505 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
507 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
509 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
510 const struct tcphdr *th, u16 *mssp);
511 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
515 u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
517 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
519 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
520 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
521 void tcp_retransmit_timer(struct sock *sk);
522 void tcp_xmit_retransmit_queue(struct sock *);
523 void tcp_simple_retransmit(struct sock *);
524 void tcp_enter_recovery(struct sock *sk, bool ece_ack);
525 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
527 TCP_FRAG_IN_WRITE_QUEUE,
528 TCP_FRAG_IN_RTX_QUEUE,
530 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
531 struct sk_buff *skb, u32 len,
532 unsigned int mss_now, gfp_t gfp);
534 void tcp_send_probe0(struct sock *);
535 void tcp_send_partial(struct sock *);
536 int tcp_write_wakeup(struct sock *, int mib);
537 void tcp_send_fin(struct sock *sk);
538 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
539 int tcp_send_synack(struct sock *);
540 void tcp_push_one(struct sock *, unsigned int mss_now);
541 void tcp_send_ack(struct sock *sk);
542 void tcp_send_delayed_ack(struct sock *sk);
543 void tcp_send_loss_probe(struct sock *sk);
544 bool tcp_schedule_loss_probe(struct sock *sk);
545 void tcp_skb_collapse_tstamp(struct sk_buff *skb,
546 const struct sk_buff *next_skb);
549 void tcp_rearm_rto(struct sock *sk);
550 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
551 void tcp_reset(struct sock *sk);
552 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
553 void tcp_fin(struct sock *sk);
556 void tcp_init_xmit_timers(struct sock *);
557 static inline void tcp_clear_xmit_timers(struct sock *sk)
559 hrtimer_cancel(&tcp_sk(sk)->pacing_timer);
560 inet_csk_clear_xmit_timers(sk);
563 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
564 unsigned int tcp_current_mss(struct sock *sk);
566 /* Bound MSS / TSO packet size with the half of the window */
567 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
571 /* When peer uses tiny windows, there is no use in packetizing
572 * to sub-MSS pieces for the sake of SWS or making sure there
573 * are enough packets in the pipe for fast recovery.
575 * On the other hand, for extremely large MSS devices, handling
576 * smaller than MSS windows in this way does make sense.
578 if (tp->max_window > TCP_MSS_DEFAULT)
579 cutoff = (tp->max_window >> 1);
581 cutoff = tp->max_window;
583 if (cutoff && pktsize > cutoff)
584 return max_t(int, cutoff, 68U - tp->tcp_header_len);
590 void tcp_get_info(struct sock *, struct tcp_info *);
592 /* Read 'sendfile()'-style from a TCP socket */
593 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
594 sk_read_actor_t recv_actor);
596 void tcp_initialize_rcv_mss(struct sock *sk);
598 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
599 int tcp_mss_to_mtu(struct sock *sk, int mss);
600 void tcp_mtup_init(struct sock *sk);
601 void tcp_init_buffer_space(struct sock *sk);
603 static inline void tcp_bound_rto(const struct sock *sk)
605 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
606 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
609 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
611 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
614 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
616 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
617 ntohl(TCP_FLAG_ACK) |
621 static inline void tcp_fast_path_on(struct tcp_sock *tp)
623 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
626 static inline void tcp_fast_path_check(struct sock *sk)
628 struct tcp_sock *tp = tcp_sk(sk);
630 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
632 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
634 tcp_fast_path_on(tp);
637 /* Compute the actual rto_min value */
638 static inline u32 tcp_rto_min(struct sock *sk)
640 const struct dst_entry *dst = __sk_dst_get(sk);
641 u32 rto_min = TCP_RTO_MIN;
643 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
644 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
648 static inline u32 tcp_rto_min_us(struct sock *sk)
650 return jiffies_to_usecs(tcp_rto_min(sk));
653 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
655 return dst_metric_locked(dst, RTAX_CC_ALGO);
658 /* Minimum RTT in usec. ~0 means not available. */
659 static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
661 return minmax_get(&tp->rtt_min);
664 /* Compute the actual receive window we are currently advertising.
665 * Rcv_nxt can be after the window if our peer push more data
666 * than the offered window.
668 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
670 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
677 /* Choose a new window, without checks for shrinking, and without
678 * scaling applied to the result. The caller does these things
679 * if necessary. This is a "raw" window selection.
681 u32 __tcp_select_window(struct sock *sk);
683 void tcp_send_window_probe(struct sock *sk);
685 /* TCP uses 32bit jiffies to save some space.
686 * Note that this is different from tcp_time_stamp, which
687 * historically has been the same until linux-4.13.
689 #define tcp_jiffies32 ((u32)jiffies)
692 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
693 * It is no longer tied to jiffies, but to 1 ms clock.
694 * Note: double check if you want to use tcp_jiffies32 instead of this.
696 #define TCP_TS_HZ 1000
698 static inline u64 tcp_clock_ns(void)
700 return local_clock();
703 static inline u64 tcp_clock_us(void)
705 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
708 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
709 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
711 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
714 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
715 static inline u32 tcp_time_stamp_raw(void)
717 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
721 /* Refresh 1us clock of a TCP socket,
722 * ensuring monotically increasing values.
724 static inline void tcp_mstamp_refresh(struct tcp_sock *tp)
726 u64 val = tcp_clock_us();
728 if (val > tp->tcp_mstamp)
729 tp->tcp_mstamp = val;
732 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
734 return max_t(s64, t1 - t0, 0);
737 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
739 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ);
743 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
745 #define TCPHDR_FIN 0x01
746 #define TCPHDR_SYN 0x02
747 #define TCPHDR_RST 0x04
748 #define TCPHDR_PSH 0x08
749 #define TCPHDR_ACK 0x10
750 #define TCPHDR_URG 0x20
751 #define TCPHDR_ECE 0x40
752 #define TCPHDR_CWR 0x80
754 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
756 /* This is what the send packet queuing engine uses to pass
757 * TCP per-packet control information to the transmission code.
758 * We also store the host-order sequence numbers in here too.
759 * This is 44 bytes if IPV6 is enabled.
760 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
763 __u32 seq; /* Starting sequence number */
764 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
766 /* Note : tcp_tw_isn is used in input path only
767 * (isn chosen by tcp_timewait_state_process())
769 * tcp_gso_segs/size are used in write queue only,
770 * cf tcp_skb_pcount()/tcp_skb_mss()
778 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
780 __u8 sacked; /* State flags for SACK/FACK. */
781 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
782 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
783 #define TCPCB_LOST 0x04 /* SKB is lost */
784 #define TCPCB_TAGBITS 0x07 /* All tag bits */
785 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
786 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
787 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
790 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
791 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
792 eor:1, /* Is skb MSG_EOR marked? */
793 has_rxtstamp:1, /* SKB has a RX timestamp */
795 __u32 ack_seq; /* Sequence number ACK'd */
798 /* There is space for up to 24 bytes */
799 __u32 in_flight:30,/* Bytes in flight at transmit */
800 is_app_limited:1, /* cwnd not fully used? */
802 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
804 /* start of send pipeline phase */
806 /* when we reached the "delivered" count */
807 u64 delivered_mstamp;
808 } tx; /* only used for outgoing skbs */
810 struct inet_skb_parm h4;
811 #if IS_ENABLED(CONFIG_IPV6)
812 struct inet6_skb_parm h6;
814 } header; /* For incoming skbs */
824 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
827 #if IS_ENABLED(CONFIG_IPV6)
828 /* This is the variant of inet6_iif() that must be used by TCP,
829 * as TCP moves IP6CB into a different location in skb->cb[]
831 static inline int tcp_v6_iif(const struct sk_buff *skb)
833 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
835 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
838 /* TCP_SKB_CB reference means this can not be used from early demux */
839 static inline int tcp_v6_sdif(const struct sk_buff *skb)
841 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
842 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
843 return TCP_SKB_CB(skb)->header.h6.iif;
849 /* TCP_SKB_CB reference means this can not be used from early demux */
850 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
852 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
853 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
854 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
860 /* TCP_SKB_CB reference means this can not be used from early demux */
861 static inline int tcp_v4_sdif(struct sk_buff *skb)
863 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
864 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
865 return TCP_SKB_CB(skb)->header.h4.iif;
870 /* Due to TSO, an SKB can be composed of multiple actual
871 * packets. To keep these tracked properly, we use this.
873 static inline int tcp_skb_pcount(const struct sk_buff *skb)
875 return TCP_SKB_CB(skb)->tcp_gso_segs;
878 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
880 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
883 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
885 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
888 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
889 static inline int tcp_skb_mss(const struct sk_buff *skb)
891 return TCP_SKB_CB(skb)->tcp_gso_size;
894 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
896 return likely(!TCP_SKB_CB(skb)->eor);
899 /* Events passed to congestion control interface */
901 CA_EVENT_TX_START, /* first transmit when no packets in flight */
902 CA_EVENT_CWND_RESTART, /* congestion window restart */
903 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
904 CA_EVENT_LOSS, /* loss timeout */
905 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
906 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
907 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
908 CA_EVENT_NON_DELAYED_ACK,
911 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
912 enum tcp_ca_ack_event_flags {
913 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
914 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
915 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
919 * Interface for adding new TCP congestion control handlers
921 #define TCP_CA_NAME_MAX 16
922 #define TCP_CA_MAX 128
923 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
925 #define TCP_CA_UNSPEC 0
927 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
928 #define TCP_CONG_NON_RESTRICTED 0x1
929 /* Requires ECN/ECT set on all packets */
930 #define TCP_CONG_NEEDS_ECN 0x2
940 /* A rate sample measures the number of (original/retransmitted) data
941 * packets delivered "delivered" over an interval of time "interval_us".
942 * The tcp_rate.c code fills in the rate sample, and congestion
943 * control modules that define a cong_control function to run at the end
944 * of ACK processing can optionally chose to consult this sample when
945 * setting cwnd and pacing rate.
946 * A sample is invalid if "delivered" or "interval_us" is negative.
949 u64 prior_mstamp; /* starting timestamp for interval */
950 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
951 s32 delivered; /* number of packets delivered over interval */
952 long interval_us; /* time for tp->delivered to incr "delivered" */
953 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
954 int losses; /* number of packets marked lost upon ACK */
955 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
956 u32 prior_in_flight; /* in flight before this ACK */
957 bool is_app_limited; /* is sample from packet with bubble in pipe? */
958 bool is_retrans; /* is sample from retransmission? */
961 struct tcp_congestion_ops {
962 struct list_head list;
966 /* initialize private data (optional) */
967 void (*init)(struct sock *sk);
968 /* cleanup private data (optional) */
969 void (*release)(struct sock *sk);
971 /* return slow start threshold (required) */
972 u32 (*ssthresh)(struct sock *sk);
973 /* do new cwnd calculation (required) */
974 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
975 /* call before changing ca_state (optional) */
976 void (*set_state)(struct sock *sk, u8 new_state);
977 /* call when cwnd event occurs (optional) */
978 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
979 /* call when ack arrives (optional) */
980 void (*in_ack_event)(struct sock *sk, u32 flags);
981 /* new value of cwnd after loss (required) */
982 u32 (*undo_cwnd)(struct sock *sk);
983 /* hook for packet ack accounting (optional) */
984 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
985 /* suggest number of segments for each skb to transmit (optional) */
986 u32 (*tso_segs_goal)(struct sock *sk);
987 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
988 u32 (*sndbuf_expand)(struct sock *sk);
989 /* call when packets are delivered to update cwnd and pacing rate,
990 * after all the ca_state processing. (optional)
992 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
993 /* get info for inet_diag (optional) */
994 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
995 union tcp_cc_info *info);
997 char name[TCP_CA_NAME_MAX];
998 struct module *owner;
1001 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1002 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1004 void tcp_assign_congestion_control(struct sock *sk);
1005 void tcp_init_congestion_control(struct sock *sk);
1006 void tcp_cleanup_congestion_control(struct sock *sk);
1007 int tcp_set_default_congestion_control(const char *name);
1008 void tcp_get_default_congestion_control(char *name);
1009 void tcp_get_available_congestion_control(char *buf, size_t len);
1010 void tcp_get_allowed_congestion_control(char *buf, size_t len);
1011 int tcp_set_allowed_congestion_control(char *allowed);
1012 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit);
1013 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1014 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1016 u32 tcp_reno_ssthresh(struct sock *sk);
1017 u32 tcp_reno_undo_cwnd(struct sock *sk);
1018 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1019 extern struct tcp_congestion_ops tcp_reno;
1021 struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1022 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
1024 char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1026 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1032 static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1034 const struct inet_connection_sock *icsk = inet_csk(sk);
1036 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1039 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1041 struct inet_connection_sock *icsk = inet_csk(sk);
1043 if (icsk->icsk_ca_ops->set_state)
1044 icsk->icsk_ca_ops->set_state(sk, ca_state);
1045 icsk->icsk_ca_state = ca_state;
1048 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1050 const struct inet_connection_sock *icsk = inet_csk(sk);
1052 if (icsk->icsk_ca_ops->cwnd_event)
1053 icsk->icsk_ca_ops->cwnd_event(sk, event);
1056 /* From tcp_rate.c */
1057 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1058 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1059 struct rate_sample *rs);
1060 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1061 struct rate_sample *rs);
1062 void tcp_rate_check_app_limited(struct sock *sk);
1064 /* These functions determine how the current flow behaves in respect of SACK
1065 * handling. SACK is negotiated with the peer, and therefore it can vary
1066 * between different flows.
1068 * tcp_is_sack - SACK enabled
1069 * tcp_is_reno - No SACK
1070 * tcp_is_fack - FACK enabled, implies SACK enabled
1072 static inline int tcp_is_sack(const struct tcp_sock *tp)
1074 return tp->rx_opt.sack_ok;
1077 static inline bool tcp_is_reno(const struct tcp_sock *tp)
1079 return !tcp_is_sack(tp);
1082 static inline bool tcp_is_fack(const struct tcp_sock *tp)
1084 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
1087 static inline void tcp_enable_fack(struct tcp_sock *tp)
1089 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
1092 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1094 return tp->sacked_out + tp->lost_out;
1097 /* This determines how many packets are "in the network" to the best
1098 * of our knowledge. In many cases it is conservative, but where
1099 * detailed information is available from the receiver (via SACK
1100 * blocks etc.) we can make more aggressive calculations.
1102 * Use this for decisions involving congestion control, use just
1103 * tp->packets_out to determine if the send queue is empty or not.
1105 * Read this equation as:
1107 * "Packets sent once on transmission queue" MINUS
1108 * "Packets left network, but not honestly ACKed yet" PLUS
1109 * "Packets fast retransmitted"
1111 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1113 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1116 #define TCP_INFINITE_SSTHRESH 0x7fffffff
1118 static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1120 return tp->snd_cwnd < tp->snd_ssthresh;
1123 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1125 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1128 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1130 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1131 (1 << inet_csk(sk)->icsk_ca_state);
1134 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1135 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1138 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1140 const struct tcp_sock *tp = tcp_sk(sk);
1142 if (tcp_in_cwnd_reduction(sk))
1143 return tp->snd_ssthresh;
1145 return max(tp->snd_ssthresh,
1146 ((tp->snd_cwnd >> 1) +
1147 (tp->snd_cwnd >> 2)));
1150 /* Use define here intentionally to get WARN_ON location shown at the caller */
1151 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1153 void tcp_enter_cwr(struct sock *sk);
1154 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1156 /* The maximum number of MSS of available cwnd for which TSO defers
1157 * sending if not using sysctl_tcp_tso_win_divisor.
1159 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1164 /* Returns end sequence number of the receiver's advertised window */
1165 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1167 return tp->snd_una + tp->snd_wnd;
1170 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1171 * flexible approach. The RFC suggests cwnd should not be raised unless
1172 * it was fully used previously. And that's exactly what we do in
1173 * congestion avoidance mode. But in slow start we allow cwnd to grow
1174 * as long as the application has used half the cwnd.
1176 * cwnd is 10 (IW10), but application sends 9 frames.
1177 * We allow cwnd to reach 18 when all frames are ACKed.
1178 * This check is safe because it's as aggressive as slow start which already
1179 * risks 100% overshoot. The advantage is that we discourage application to
1180 * either send more filler packets or data to artificially blow up the cwnd
1181 * usage, and allow application-limited process to probe bw more aggressively.
1183 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1185 const struct tcp_sock *tp = tcp_sk(sk);
1187 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1188 if (tcp_in_slow_start(tp))
1189 return tp->snd_cwnd < 2 * tp->max_packets_out;
1191 return tp->is_cwnd_limited;
1194 /* Something is really bad, we could not queue an additional packet,
1195 * because qdisc is full or receiver sent a 0 window.
1196 * We do not want to add fuel to the fire, or abort too early,
1197 * so make sure the timer we arm now is at least 200ms in the future,
1198 * regardless of current icsk_rto value (as it could be ~2ms)
1200 static inline unsigned long tcp_probe0_base(const struct sock *sk)
1202 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1205 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1206 static inline unsigned long tcp_probe0_when(const struct sock *sk,
1207 unsigned long max_when)
1209 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1211 return (unsigned long)min_t(u64, when, max_when);
1214 static inline void tcp_check_probe_timer(struct sock *sk)
1216 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1217 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1218 tcp_probe0_base(sk), TCP_RTO_MAX);
1221 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1226 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1232 * Calculate(/check) TCP checksum
1234 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1235 __be32 daddr, __wsum base)
1237 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1240 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1242 return __skb_checksum_complete(skb);
1245 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1247 return !skb_csum_unnecessary(skb) &&
1248 __tcp_checksum_complete(skb);
1251 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1252 int tcp_filter(struct sock *sk, struct sk_buff *skb);
1257 static const char *statename[]={
1258 "Unused","Established","Syn Sent","Syn Recv",
1259 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1260 "Close Wait","Last ACK","Listen","Closing"
1263 void tcp_set_state(struct sock *sk, int state);
1265 void tcp_done(struct sock *sk);
1267 int tcp_abort(struct sock *sk, int err);
1269 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1272 rx_opt->num_sacks = 0;
1275 u32 tcp_default_init_rwnd(u32 mss);
1276 void tcp_cwnd_restart(struct sock *sk, s32 delta);
1278 static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1280 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1281 struct tcp_sock *tp = tcp_sk(sk);
1284 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1285 ca_ops->cong_control)
1287 delta = tcp_jiffies32 - tp->lsndtime;
1288 if (delta > inet_csk(sk)->icsk_rto)
1289 tcp_cwnd_restart(sk, delta);
1292 /* Determine a window scaling and initial window to offer. */
1293 void tcp_select_initial_window(const struct sock *sk, int __space,
1294 __u32 mss, __u32 *rcv_wnd,
1295 __u32 *window_clamp, int wscale_ok,
1296 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1298 static inline int tcp_win_from_space(const struct sock *sk, int space)
1300 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1302 return tcp_adv_win_scale <= 0 ?
1303 (space>>(-tcp_adv_win_scale)) :
1304 space - (space>>tcp_adv_win_scale);
1307 /* Note: caller must be prepared to deal with negative returns */
1308 static inline int tcp_space(const struct sock *sk)
1310 return tcp_win_from_space(sk, sk->sk_rcvbuf -
1311 atomic_read(&sk->sk_rmem_alloc));
1314 static inline int tcp_full_space(const struct sock *sk)
1316 return tcp_win_from_space(sk, sk->sk_rcvbuf);
1319 extern void tcp_openreq_init_rwin(struct request_sock *req,
1320 const struct sock *sk_listener,
1321 const struct dst_entry *dst);
1323 void tcp_enter_memory_pressure(struct sock *sk);
1324 void tcp_leave_memory_pressure(struct sock *sk);
1326 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1328 struct net *net = sock_net((struct sock *)tp);
1330 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1333 static inline int keepalive_time_when(const struct tcp_sock *tp)
1335 struct net *net = sock_net((struct sock *)tp);
1337 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1340 static inline int keepalive_probes(const struct tcp_sock *tp)
1342 struct net *net = sock_net((struct sock *)tp);
1344 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1347 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1349 const struct inet_connection_sock *icsk = &tp->inet_conn;
1351 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1352 tcp_jiffies32 - tp->rcv_tstamp);
1355 static inline int tcp_fin_time(const struct sock *sk)
1357 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1358 const int rto = inet_csk(sk)->icsk_rto;
1360 if (fin_timeout < (rto << 2) - (rto >> 1))
1361 fin_timeout = (rto << 2) - (rto >> 1);
1366 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1369 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1371 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1374 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1375 * then following tcp messages have valid values. Ignore 0 value,
1376 * or else 'negative' tsval might forbid us to accept their packets.
1378 if (!rx_opt->ts_recent)
1383 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1386 if (tcp_paws_check(rx_opt, 0))
1389 /* RST segments are not recommended to carry timestamp,
1390 and, if they do, it is recommended to ignore PAWS because
1391 "their cleanup function should take precedence over timestamps."
1392 Certainly, it is mistake. It is necessary to understand the reasons
1393 of this constraint to relax it: if peer reboots, clock may go
1394 out-of-sync and half-open connections will not be reset.
1395 Actually, the problem would be not existing if all
1396 the implementations followed draft about maintaining clock
1397 via reboots. Linux-2.2 DOES NOT!
1399 However, we can relax time bounds for RST segments to MSL.
1401 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1406 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1407 int mib_idx, u32 *last_oow_ack_time);
1409 static inline void tcp_mib_init(struct net *net)
1412 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1413 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1414 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1415 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1419 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1421 tp->lost_skb_hint = NULL;
1424 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1426 tcp_clear_retrans_hints_partial(tp);
1427 tp->retransmit_skb_hint = NULL;
1430 union tcp_md5_addr {
1432 #if IS_ENABLED(CONFIG_IPV6)
1437 /* - key database */
1438 struct tcp_md5sig_key {
1439 struct hlist_node node;
1441 u8 family; /* AF_INET or AF_INET6 */
1442 union tcp_md5_addr addr;
1444 u8 key[TCP_MD5SIG_MAXKEYLEN];
1445 struct rcu_head rcu;
1449 struct tcp_md5sig_info {
1450 struct hlist_head head;
1451 struct rcu_head rcu;
1454 /* - pseudo header */
1455 struct tcp4_pseudohdr {
1463 struct tcp6_pseudohdr {
1464 struct in6_addr saddr;
1465 struct in6_addr daddr;
1467 __be32 protocol; /* including padding */
1470 union tcp_md5sum_block {
1471 struct tcp4_pseudohdr ip4;
1472 #if IS_ENABLED(CONFIG_IPV6)
1473 struct tcp6_pseudohdr ip6;
1477 /* - pool: digest algorithm, hash description and scratch buffer */
1478 struct tcp_md5sig_pool {
1479 struct ahash_request *md5_req;
1484 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1485 const struct sock *sk, const struct sk_buff *skb);
1486 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1487 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
1489 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1490 int family, u8 prefixlen);
1491 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1492 const struct sock *addr_sk);
1494 #ifdef CONFIG_TCP_MD5SIG
1495 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1496 const union tcp_md5_addr *addr,
1498 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1500 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1501 const union tcp_md5_addr *addr,
1506 #define tcp_twsk_md5_key(twsk) NULL
1509 bool tcp_alloc_md5sig_pool(void);
1511 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1512 static inline void tcp_put_md5sig_pool(void)
1517 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1518 unsigned int header_len);
1519 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1520 const struct tcp_md5sig_key *key);
1522 /* From tcp_fastopen.c */
1523 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1524 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1525 unsigned long *last_syn_loss);
1526 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1527 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1529 struct tcp_fastopen_request {
1530 /* Fast Open cookie. Size 0 means a cookie request */
1531 struct tcp_fastopen_cookie cookie;
1532 struct msghdr *data; /* data in MSG_FASTOPEN */
1534 int copied; /* queued in tcp_connect() */
1536 void tcp_free_fastopen_req(struct tcp_sock *tp);
1537 void tcp_fastopen_destroy_cipher(struct sock *sk);
1538 void tcp_fastopen_ctx_destroy(struct net *net);
1539 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1540 void *key, unsigned int len);
1541 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1542 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1543 struct request_sock *req,
1544 struct tcp_fastopen_cookie *foc,
1545 const struct dst_entry *dst);
1546 void tcp_fastopen_init_key_once(struct net *net);
1547 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1548 struct tcp_fastopen_cookie *cookie);
1549 bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1550 #define TCP_FASTOPEN_KEY_LENGTH 16
1552 /* Fastopen key context */
1553 struct tcp_fastopen_context {
1554 struct crypto_cipher *tfm;
1555 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1556 struct rcu_head rcu;
1559 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1560 void tcp_fastopen_active_disable(struct sock *sk);
1561 bool tcp_fastopen_active_should_disable(struct sock *sk);
1562 void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1563 void tcp_fastopen_active_timeout_reset(void);
1565 /* Latencies incurred by various limits for a sender. They are
1566 * chronograph-like stats that are mutually exclusive.
1570 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1571 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1572 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1576 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1577 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1579 /* This helper is needed, because skb->tcp_tsorted_anchor uses
1580 * the same memory storage than skb->destructor/_skb_refdst
1582 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1584 skb->destructor = NULL;
1585 skb->_skb_refdst = 0UL;
1588 #define tcp_skb_tsorted_save(skb) { \
1589 unsigned long _save = skb->_skb_refdst; \
1590 skb->_skb_refdst = 0UL;
1592 #define tcp_skb_tsorted_restore(skb) \
1593 skb->_skb_refdst = _save; \
1596 void tcp_write_queue_purge(struct sock *sk);
1598 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1600 return skb_rb_first(&sk->tcp_rtx_queue);
1603 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1605 return skb_peek(&sk->sk_write_queue);
1608 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1610 return skb_peek_tail(&sk->sk_write_queue);
1613 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1614 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1616 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1618 return skb_peek(&sk->sk_write_queue);
1621 static inline bool tcp_skb_is_last(const struct sock *sk,
1622 const struct sk_buff *skb)
1624 return skb_queue_is_last(&sk->sk_write_queue, skb);
1627 static inline bool tcp_write_queue_empty(const struct sock *sk)
1629 return skb_queue_empty(&sk->sk_write_queue);
1632 static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1634 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1637 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1639 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1642 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1644 if (tcp_write_queue_empty(sk))
1645 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1647 if (tcp_sk(sk)->highest_sack == skb_unlinked)
1648 tcp_sk(sk)->highest_sack = NULL;
1651 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1653 __skb_queue_tail(&sk->sk_write_queue, skb);
1656 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1658 __tcp_add_write_queue_tail(sk, skb);
1660 /* Queue it, remembering where we must start sending. */
1661 if (sk->sk_write_queue.next == skb) {
1662 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1664 if (tcp_sk(sk)->highest_sack == NULL)
1665 tcp_sk(sk)->highest_sack = skb;
1669 /* Insert new before skb on the write queue of sk. */
1670 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1671 struct sk_buff *skb,
1674 __skb_queue_before(&sk->sk_write_queue, skb, new);
1677 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1679 tcp_skb_tsorted_anchor_cleanup(skb);
1680 __skb_unlink(skb, &sk->sk_write_queue);
1683 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1685 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1687 tcp_skb_tsorted_anchor_cleanup(skb);
1688 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1691 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1693 list_del(&skb->tcp_tsorted_anchor);
1694 tcp_rtx_queue_unlink(skb, sk);
1695 sk_wmem_free_skb(sk, skb);
1698 static inline void tcp_push_pending_frames(struct sock *sk)
1700 if (tcp_send_head(sk)) {
1701 struct tcp_sock *tp = tcp_sk(sk);
1703 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1707 /* Start sequence of the skb just after the highest skb with SACKed
1708 * bit, valid only if sacked_out > 0 or when the caller has ensured
1709 * validity by itself.
1711 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1713 if (!tp->sacked_out)
1716 if (tp->highest_sack == NULL)
1719 return TCP_SKB_CB(tp->highest_sack)->seq;
1722 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1724 struct sk_buff *next = skb_rb_next(skb);
1726 tcp_sk(sk)->highest_sack = next ?: tcp_send_head(sk);
1729 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1731 return tcp_sk(sk)->highest_sack;
1734 static inline void tcp_highest_sack_reset(struct sock *sk)
1736 struct sk_buff *skb = tcp_rtx_queue_head(sk);
1738 tcp_sk(sk)->highest_sack = skb ?: tcp_send_head(sk);
1741 /* Called when old skb is about to be deleted and replaced by new skb */
1742 static inline void tcp_highest_sack_replace(struct sock *sk,
1743 struct sk_buff *old,
1744 struct sk_buff *new)
1746 if (old == tcp_highest_sack(sk))
1747 tcp_sk(sk)->highest_sack = new;
1750 /* This helper checks if socket has IP_TRANSPARENT set */
1751 static inline bool inet_sk_transparent(const struct sock *sk)
1753 switch (sk->sk_state) {
1755 return inet_twsk(sk)->tw_transparent;
1756 case TCP_NEW_SYN_RECV:
1757 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1759 return inet_sk(sk)->transparent;
1762 /* Determines whether this is a thin stream (which may suffer from
1763 * increased latency). Used to trigger latency-reducing mechanisms.
1765 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1767 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1771 enum tcp_seq_states {
1772 TCP_SEQ_STATE_LISTENING,
1773 TCP_SEQ_STATE_ESTABLISHED,
1776 int tcp_seq_open(struct inode *inode, struct file *file);
1778 struct tcp_seq_afinfo {
1781 const struct file_operations *seq_fops;
1782 struct seq_operations seq_ops;
1785 struct tcp_iter_state {
1786 struct seq_net_private p;
1788 enum tcp_seq_states state;
1789 struct sock *syn_wait_sk;
1790 int bucket, offset, sbucket, num;
1794 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1795 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1797 extern struct request_sock_ops tcp_request_sock_ops;
1798 extern struct request_sock_ops tcp6_request_sock_ops;
1800 void tcp_v4_destroy_sock(struct sock *sk);
1802 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1803 netdev_features_t features);
1804 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1805 int tcp_gro_complete(struct sk_buff *skb);
1807 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1809 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1811 struct net *net = sock_net((struct sock *)tp);
1812 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1815 static inline bool tcp_stream_memory_free(const struct sock *sk)
1817 const struct tcp_sock *tp = tcp_sk(sk);
1818 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1820 return notsent_bytes < tcp_notsent_lowat(tp);
1823 #ifdef CONFIG_PROC_FS
1824 int tcp4_proc_init(void);
1825 void tcp4_proc_exit(void);
1828 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1829 int tcp_conn_request(struct request_sock_ops *rsk_ops,
1830 const struct tcp_request_sock_ops *af_ops,
1831 struct sock *sk, struct sk_buff *skb);
1833 /* TCP af-specific functions */
1834 struct tcp_sock_af_ops {
1835 #ifdef CONFIG_TCP_MD5SIG
1836 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1837 const struct sock *addr_sk);
1838 int (*calc_md5_hash)(char *location,
1839 const struct tcp_md5sig_key *md5,
1840 const struct sock *sk,
1841 const struct sk_buff *skb);
1842 int (*md5_parse)(struct sock *sk,
1844 char __user *optval,
1849 struct tcp_request_sock_ops {
1851 #ifdef CONFIG_TCP_MD5SIG
1852 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1853 const struct sock *addr_sk);
1854 int (*calc_md5_hash) (char *location,
1855 const struct tcp_md5sig_key *md5,
1856 const struct sock *sk,
1857 const struct sk_buff *skb);
1859 void (*init_req)(struct request_sock *req,
1860 const struct sock *sk_listener,
1861 struct sk_buff *skb);
1862 #ifdef CONFIG_SYN_COOKIES
1863 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1866 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1867 const struct request_sock *req);
1868 u32 (*init_seq)(const struct sk_buff *skb);
1869 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1870 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1871 struct flowi *fl, struct request_sock *req,
1872 struct tcp_fastopen_cookie *foc,
1873 enum tcp_synack_type synack_type);
1876 #ifdef CONFIG_SYN_COOKIES
1877 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1878 const struct sock *sk, struct sk_buff *skb,
1881 tcp_synq_overflow(sk);
1882 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1883 return ops->cookie_init_seq(skb, mss);
1886 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1887 const struct sock *sk, struct sk_buff *skb,
1894 int tcpv4_offload_init(void);
1896 void tcp_v4_init(void);
1897 void tcp_init(void);
1899 /* tcp_recovery.c */
1900 extern void tcp_rack_mark_lost(struct sock *sk);
1901 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
1903 extern void tcp_rack_reo_timeout(struct sock *sk);
1905 /* At how many usecs into the future should the RTO fire? */
1906 static inline s64 tcp_rto_delta_us(const struct sock *sk)
1908 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
1909 u32 rto = inet_csk(sk)->icsk_rto;
1910 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto);
1912 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
1916 * Save and compile IPv4 options, return a pointer to it
1918 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
1919 struct sk_buff *skb)
1921 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1922 struct ip_options_rcu *dopt = NULL;
1925 int opt_size = sizeof(*dopt) + opt->optlen;
1927 dopt = kmalloc(opt_size, GFP_ATOMIC);
1928 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
1936 /* locally generated TCP pure ACKs have skb->truesize == 2
1937 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1938 * This is much faster than dissecting the packet to find out.
1939 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1941 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1943 return skb->truesize == 2;
1946 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1951 static inline int tcp_inq(struct sock *sk)
1953 struct tcp_sock *tp = tcp_sk(sk);
1956 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1958 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1960 before(tp->urg_seq, tp->copied_seq) ||
1961 !before(tp->urg_seq, tp->rcv_nxt)) {
1963 answ = tp->rcv_nxt - tp->copied_seq;
1965 /* Subtract 1, if FIN was received */
1966 if (answ && sock_flag(sk, SOCK_DONE))
1969 answ = tp->urg_seq - tp->copied_seq;
1975 int tcp_peek_len(struct socket *sock);
1977 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1981 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1982 tp->segs_in += segs_in;
1983 if (skb->len > tcp_hdrlen(skb))
1984 tp->data_segs_in += segs_in;
1988 * TCP listen path runs lockless.
1989 * We forced "struct sock" to be const qualified to make sure
1990 * we don't modify one of its field by mistake.
1991 * Here, we increment sk_drops which is an atomic_t, so we can safely
1992 * make sock writable again.
1994 static inline void tcp_listendrop(const struct sock *sk)
1996 atomic_inc(&((struct sock *)sk)->sk_drops);
1997 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2000 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2003 * Interface for adding Upper Level Protocols over TCP
2006 #define TCP_ULP_NAME_MAX 16
2007 #define TCP_ULP_MAX 128
2008 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2010 struct tcp_ulp_ops {
2011 struct list_head list;
2013 /* initialize ulp */
2014 int (*init)(struct sock *sk);
2016 void (*release)(struct sock *sk);
2018 char name[TCP_ULP_NAME_MAX];
2019 struct module *owner;
2021 int tcp_register_ulp(struct tcp_ulp_ops *type);
2022 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2023 int tcp_set_ulp(struct sock *sk, const char *name);
2024 void tcp_get_available_ulp(char *buf, size_t len);
2025 void tcp_cleanup_ulp(struct sock *sk);
2027 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2028 * is < 0, then the BPF op failed (for example if the loaded BPF
2029 * program does not support the chosen operation or there is no BPF
2033 static inline int tcp_call_bpf(struct sock *sk, int op)
2035 struct bpf_sock_ops_kern sock_ops;
2038 if (sk_fullsock(sk))
2039 sock_owned_by_me(sk);
2041 memset(&sock_ops, 0, sizeof(sock_ops));
2045 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2047 ret = sock_ops.reply;
2053 static inline int tcp_call_bpf(struct sock *sk, int op)
2059 static inline u32 tcp_timeout_init(struct sock *sk)
2063 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT);
2066 timeout = TCP_TIMEOUT_INIT;
2070 static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2074 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT);
2081 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2083 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1);
2086 #if IS_ENABLED(CONFIG_SMC)
2087 extern struct static_key_false tcp_have_smc;