1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
7 * Definitions for the TCP module.
9 * Version: @(#)tcp.h 1.0.5 05/23/93
12 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
17 #define FASTRETRANS_DEBUG 1
19 #include <linux/list.h>
20 #include <linux/tcp.h>
21 #include <linux/bug.h>
22 #include <linux/slab.h>
23 #include <linux/cache.h>
24 #include <linux/percpu.h>
25 #include <linux/skbuff.h>
26 #include <linux/kref.h>
27 #include <linux/ktime.h>
28 #include <linux/indirect_call_wrapper.h>
30 #include <net/inet_connection_sock.h>
31 #include <net/inet_timewait_sock.h>
32 #include <net/inet_hashtables.h>
33 #include <net/checksum.h>
34 #include <net/request_sock.h>
35 #include <net/sock_reuseport.h>
39 #include <net/tcp_states.h>
40 #include <net/inet_ecn.h>
42 #include <net/mptcp.h>
44 #include <linux/seq_file.h>
45 #include <linux/memcontrol.h>
46 #include <linux/bpf-cgroup.h>
47 #include <linux/siphash.h>
49 extern struct inet_hashinfo tcp_hashinfo;
51 extern struct percpu_counter tcp_orphan_count;
52 void tcp_time_wait(struct sock *sk, int state, int timeo);
54 #define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER)
55 #define MAX_TCP_OPTION_SPACE 40
56 #define TCP_MIN_SND_MSS 48
57 #define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
60 * Never offer a window over 32767 without using window scaling. Some
61 * poor stacks do signed 16bit maths!
63 #define MAX_TCP_WINDOW 32767U
65 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
66 #define TCP_MIN_MSS 88U
68 /* The initial MTU to use for probing */
69 #define TCP_BASE_MSS 1024
71 /* probing interval, default to 10 minutes as per RFC4821 */
72 #define TCP_PROBE_INTERVAL 600
74 /* Specify interval when tcp mtu probing will stop */
75 #define TCP_PROBE_THRESHOLD 8
77 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
78 #define TCP_FASTRETRANS_THRESH 3
80 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
81 #define TCP_MAX_QUICKACKS 16U
83 /* Maximal number of window scale according to RFC1323 */
84 #define TCP_MAX_WSCALE 14U
87 #define TCP_URG_VALID 0x0100
88 #define TCP_URG_NOTYET 0x0200
89 #define TCP_URG_READ 0x0400
91 #define TCP_RETR1 3 /*
92 * This is how many retries it does before it
93 * tries to figure out if the gateway is
94 * down. Minimal RFC value is 3; it corresponds
95 * to ~3sec-8min depending on RTO.
98 #define TCP_RETR2 15 /*
99 * This should take at least
100 * 90 minutes to time out.
101 * RFC1122 says that the limit is 100 sec.
102 * 15 is ~13-30min depending on RTO.
105 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
106 * when active opening a connection.
107 * RFC1122 says the minimum retry MUST
108 * be at least 180secs. Nevertheless
109 * this value is corresponding to
110 * 63secs of retransmission with the
111 * current initial RTO.
114 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
115 * when passive opening a connection.
116 * This is corresponding to 31secs of
117 * retransmission with the current
121 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
122 * state, about 60 seconds */
123 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
124 /* BSD style FIN_WAIT2 deadlock breaker.
125 * It used to be 3min, new value is 60sec,
126 * to combine FIN-WAIT-2 timeout with
129 #define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
131 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
133 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
134 #define TCP_ATO_MIN ((unsigned)(HZ/25))
136 #define TCP_DELACK_MIN 4U
137 #define TCP_ATO_MIN 4U
139 #define TCP_RTO_MAX ((unsigned)(120*HZ))
140 #define TCP_RTO_MIN ((unsigned)(HZ/5))
141 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
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_KEEPALIVE_TIME (120*60*HZ) /* two hours */
154 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
155 #define TCP_KEEPALIVE_INTVL (75*HZ)
157 #define MAX_TCP_KEEPIDLE 32767
158 #define MAX_TCP_KEEPINTVL 32767
159 #define MAX_TCP_KEEPCNT 127
160 #define MAX_TCP_SYNCNT 127
162 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
164 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
165 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
166 * after this time. It should be equal
167 * (or greater than) TCP_TIMEWAIT_LEN
168 * to provide reliability equal to one
169 * provided by timewait state.
171 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
172 * timestamps. It must be less than
173 * minimal timewait lifetime.
179 #define TCPOPT_NOP 1 /* Padding */
180 #define TCPOPT_EOL 0 /* End of options */
181 #define TCPOPT_MSS 2 /* Segment size negotiating */
182 #define TCPOPT_WINDOW 3 /* Window scaling */
183 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
184 #define TCPOPT_SACK 5 /* SACK Block */
185 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
186 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
187 #define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */
188 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
189 #define TCPOPT_EXP 254 /* Experimental */
190 /* Magic number to be after the option value for sharing TCP
191 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
193 #define TCPOPT_FASTOPEN_MAGIC 0xF989
194 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9
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
207 #define TCPOLEN_EXP_SMC_BASE 6
209 /* But this is what stacks really send out. */
210 #define TCPOLEN_TSTAMP_ALIGNED 12
211 #define TCPOLEN_WSCALE_ALIGNED 4
212 #define TCPOLEN_SACKPERM_ALIGNED 4
213 #define TCPOLEN_SACK_BASE 2
214 #define TCPOLEN_SACK_BASE_ALIGNED 4
215 #define TCPOLEN_SACK_PERBLOCK 8
216 #define TCPOLEN_MD5SIG_ALIGNED 20
217 #define TCPOLEN_MSS_ALIGNED 4
218 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
220 /* Flags in tp->nonagle */
221 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
222 #define TCP_NAGLE_CORK 2 /* Socket is corked */
223 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
225 /* TCP thin-stream limits */
226 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
228 /* TCP initial congestion window as per rfc6928 */
229 #define TCP_INIT_CWND 10
231 /* Bit Flags for sysctl_tcp_fastopen */
232 #define TFO_CLIENT_ENABLE 1
233 #define TFO_SERVER_ENABLE 2
234 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
236 /* Accept SYN data w/o any cookie option */
237 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
239 /* Force enable TFO on all listeners, i.e., not requiring the
240 * TCP_FASTOPEN socket option.
242 #define TFO_SERVER_WO_SOCKOPT1 0x400
245 /* sysctl variables for tcp */
246 extern int sysctl_tcp_max_orphans;
247 extern long sysctl_tcp_mem[3];
249 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
250 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
251 #define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
253 extern atomic_long_t tcp_memory_allocated;
254 extern struct percpu_counter tcp_sockets_allocated;
255 extern unsigned long tcp_memory_pressure;
257 /* optimized version of sk_under_memory_pressure() for TCP sockets */
258 static inline bool tcp_under_memory_pressure(const struct sock *sk)
260 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
261 mem_cgroup_under_socket_pressure(sk->sk_memcg))
264 return READ_ONCE(tcp_memory_pressure);
267 * The next routines deal with comparing 32 bit unsigned ints
268 * and worry about wraparound (automatic with unsigned arithmetic).
271 static inline bool before(__u32 seq1, __u32 seq2)
273 return (__s32)(seq1-seq2) < 0;
275 #define after(seq2, seq1) before(seq1, seq2)
277 /* is s2<=s1<=s3 ? */
278 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
280 return seq3 - seq2 >= seq1 - seq2;
283 static inline bool tcp_out_of_memory(struct sock *sk)
285 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
286 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
291 void sk_forced_mem_schedule(struct sock *sk, int size);
293 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
295 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
296 int orphans = percpu_counter_read_positive(ocp);
298 if (orphans << shift > sysctl_tcp_max_orphans) {
299 orphans = percpu_counter_sum_positive(ocp);
300 if (orphans << shift > sysctl_tcp_max_orphans)
306 bool tcp_check_oom(struct sock *sk, int shift);
309 extern struct proto tcp_prot;
311 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
312 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
313 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
314 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
316 void tcp_tasklet_init(void);
318 int tcp_v4_err(struct sk_buff *skb, u32);
320 void tcp_shutdown(struct sock *sk, int how);
322 int tcp_v4_early_demux(struct sk_buff *skb);
323 int tcp_v4_rcv(struct sk_buff *skb);
325 void tcp_remove_empty_skb(struct sock *sk, struct sk_buff *skb);
326 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
327 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
328 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
329 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
331 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
332 size_t size, int flags);
333 struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
334 struct page *page, int offset, size_t *size);
335 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
336 size_t size, int flags);
337 int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
338 void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
340 void tcp_release_cb(struct sock *sk);
341 void tcp_wfree(struct sk_buff *skb);
342 void tcp_write_timer_handler(struct sock *sk);
343 void tcp_delack_timer_handler(struct sock *sk);
344 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
345 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
346 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
347 void tcp_rcv_space_adjust(struct sock *sk);
348 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
349 void tcp_twsk_destructor(struct sock *sk);
350 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
351 struct pipe_inode_info *pipe, size_t len,
354 void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
355 static inline void tcp_dec_quickack_mode(struct sock *sk,
356 const unsigned int pkts)
358 struct inet_connection_sock *icsk = inet_csk(sk);
360 if (icsk->icsk_ack.quick) {
361 if (pkts >= icsk->icsk_ack.quick) {
362 icsk->icsk_ack.quick = 0;
363 /* Leaving quickack mode we deflate ATO. */
364 icsk->icsk_ack.ato = TCP_ATO_MIN;
366 icsk->icsk_ack.quick -= pkts;
371 #define TCP_ECN_QUEUE_CWR 2
372 #define TCP_ECN_DEMAND_CWR 4
373 #define TCP_ECN_SEEN 8
383 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
385 const struct tcphdr *th);
386 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
387 struct request_sock *req, bool fastopen,
389 int tcp_child_process(struct sock *parent, struct sock *child,
390 struct sk_buff *skb);
391 void tcp_enter_loss(struct sock *sk);
392 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
393 void tcp_clear_retrans(struct tcp_sock *tp);
394 void tcp_update_metrics(struct sock *sk);
395 void tcp_init_metrics(struct sock *sk);
396 void tcp_metrics_init(void);
397 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
398 void __tcp_close(struct sock *sk, long timeout);
399 void tcp_close(struct sock *sk, long timeout);
400 void tcp_init_sock(struct sock *sk);
401 void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb);
402 __poll_t tcp_poll(struct file *file, struct socket *sock,
403 struct poll_table_struct *wait);
404 int tcp_getsockopt(struct sock *sk, int level, int optname,
405 char __user *optval, int __user *optlen);
406 int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
407 unsigned int optlen);
408 void tcp_set_keepalive(struct sock *sk, int val);
409 void tcp_syn_ack_timeout(const struct request_sock *req);
410 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
411 int flags, int *addr_len);
412 int tcp_set_rcvlowat(struct sock *sk, int val);
413 int tcp_set_window_clamp(struct sock *sk, int val);
414 void tcp_data_ready(struct sock *sk);
416 int tcp_mmap(struct file *file, struct socket *sock,
417 struct vm_area_struct *vma);
419 void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
420 struct tcp_options_received *opt_rx,
421 int estab, struct tcp_fastopen_cookie *foc);
422 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
425 * BPF SKB-less helpers
427 u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
428 struct tcphdr *th, u32 *cookie);
429 u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
430 struct tcphdr *th, u32 *cookie);
431 u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
432 const struct tcp_request_sock_ops *af_ops,
433 struct sock *sk, struct tcphdr *th);
435 * TCP v4 functions exported for the inet6 API
438 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
439 void tcp_v4_mtu_reduced(struct sock *sk);
440 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
441 void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
442 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
443 struct sock *tcp_create_openreq_child(const struct sock *sk,
444 struct request_sock *req,
445 struct sk_buff *skb);
446 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
447 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
448 struct request_sock *req,
449 struct dst_entry *dst,
450 struct request_sock *req_unhash,
452 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
453 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
454 int tcp_connect(struct sock *sk);
455 enum tcp_synack_type {
460 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
461 struct request_sock *req,
462 struct tcp_fastopen_cookie *foc,
463 enum tcp_synack_type synack_type,
464 struct sk_buff *syn_skb);
465 int tcp_disconnect(struct sock *sk, int flags);
467 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
468 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
469 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
471 /* From syncookies.c */
472 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
473 struct request_sock *req,
474 struct dst_entry *dst, u32 tsoff);
475 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
477 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
478 struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
479 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 int last_overflow;
500 unsigned int now = jiffies;
502 if (sk->sk_reuseport) {
503 struct sock_reuseport *reuse;
505 reuse = rcu_dereference(sk->sk_reuseport_cb);
507 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
508 if (!time_between32(now, last_overflow,
510 WRITE_ONCE(reuse->synq_overflow_ts, now);
515 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
516 if (!time_between32(now, last_overflow, last_overflow + HZ))
517 WRITE_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp, now);
520 /* syncookies: no recent synqueue overflow on this listening socket? */
521 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
523 unsigned int last_overflow;
524 unsigned int now = jiffies;
526 if (sk->sk_reuseport) {
527 struct sock_reuseport *reuse;
529 reuse = rcu_dereference(sk->sk_reuseport_cb);
531 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
532 return !time_between32(now, last_overflow - HZ,
534 TCP_SYNCOOKIE_VALID);
538 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
540 /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
541 * then we're under synflood. However, we have to use
542 * 'last_overflow - HZ' as lower bound. That's because a concurrent
543 * tcp_synq_overflow() could update .ts_recent_stamp after we read
544 * jiffies but before we store .ts_recent_stamp into last_overflow,
545 * which could lead to rejecting a valid syncookie.
547 return !time_between32(now, last_overflow - HZ,
548 last_overflow + TCP_SYNCOOKIE_VALID);
551 static inline u32 tcp_cookie_time(void)
553 u64 val = get_jiffies_64();
555 do_div(val, TCP_SYNCOOKIE_PERIOD);
559 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
561 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
562 u64 cookie_init_timestamp(struct request_sock *req, u64 now);
563 bool cookie_timestamp_decode(const struct net *net,
564 struct tcp_options_received *opt);
565 bool cookie_ecn_ok(const struct tcp_options_received *opt,
566 const struct net *net, const struct dst_entry *dst);
568 /* From net/ipv6/syncookies.c */
569 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
571 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
573 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
574 const struct tcphdr *th, u16 *mssp);
575 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
579 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
581 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
582 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
583 void tcp_retransmit_timer(struct sock *sk);
584 void tcp_xmit_retransmit_queue(struct sock *);
585 void tcp_simple_retransmit(struct sock *);
586 void tcp_enter_recovery(struct sock *sk, bool ece_ack);
587 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
589 TCP_FRAG_IN_WRITE_QUEUE,
590 TCP_FRAG_IN_RTX_QUEUE,
592 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
593 struct sk_buff *skb, u32 len,
594 unsigned int mss_now, gfp_t gfp);
596 void tcp_send_probe0(struct sock *);
597 void tcp_send_partial(struct sock *);
598 int tcp_write_wakeup(struct sock *, int mib);
599 void tcp_send_fin(struct sock *sk);
600 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
601 int tcp_send_synack(struct sock *);
602 void tcp_push_one(struct sock *, unsigned int mss_now);
603 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
604 void tcp_send_ack(struct sock *sk);
605 void tcp_send_delayed_ack(struct sock *sk);
606 void tcp_send_loss_probe(struct sock *sk);
607 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
608 void tcp_skb_collapse_tstamp(struct sk_buff *skb,
609 const struct sk_buff *next_skb);
612 void tcp_rearm_rto(struct sock *sk);
613 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
614 void tcp_reset(struct sock *sk, struct sk_buff *skb);
615 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
616 void tcp_fin(struct sock *sk);
619 void tcp_init_xmit_timers(struct sock *);
620 static inline void tcp_clear_xmit_timers(struct sock *sk)
622 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
625 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
628 inet_csk_clear_xmit_timers(sk);
631 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
632 unsigned int tcp_current_mss(struct sock *sk);
634 /* Bound MSS / TSO packet size with the half of the window */
635 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
639 /* When peer uses tiny windows, there is no use in packetizing
640 * to sub-MSS pieces for the sake of SWS or making sure there
641 * are enough packets in the pipe for fast recovery.
643 * On the other hand, for extremely large MSS devices, handling
644 * smaller than MSS windows in this way does make sense.
646 if (tp->max_window > TCP_MSS_DEFAULT)
647 cutoff = (tp->max_window >> 1);
649 cutoff = tp->max_window;
651 if (cutoff && pktsize > cutoff)
652 return max_t(int, cutoff, 68U - tp->tcp_header_len);
658 void tcp_get_info(struct sock *, struct tcp_info *);
660 /* Read 'sendfile()'-style from a TCP socket */
661 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
662 sk_read_actor_t recv_actor);
664 void tcp_initialize_rcv_mss(struct sock *sk);
666 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
667 int tcp_mss_to_mtu(struct sock *sk, int mss);
668 void tcp_mtup_init(struct sock *sk);
670 static inline void tcp_bound_rto(const struct sock *sk)
672 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
673 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
676 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
678 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
681 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
683 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
684 ntohl(TCP_FLAG_ACK) |
688 static inline void tcp_fast_path_on(struct tcp_sock *tp)
690 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
693 static inline void tcp_fast_path_check(struct sock *sk)
695 struct tcp_sock *tp = tcp_sk(sk);
697 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
699 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
701 tcp_fast_path_on(tp);
704 /* Compute the actual rto_min value */
705 static inline u32 tcp_rto_min(struct sock *sk)
707 const struct dst_entry *dst = __sk_dst_get(sk);
708 u32 rto_min = inet_csk(sk)->icsk_rto_min;
710 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
711 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
715 static inline u32 tcp_rto_min_us(struct sock *sk)
717 return jiffies_to_usecs(tcp_rto_min(sk));
720 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
722 return dst_metric_locked(dst, RTAX_CC_ALGO);
725 /* Minimum RTT in usec. ~0 means not available. */
726 static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
728 return minmax_get(&tp->rtt_min);
731 /* Compute the actual receive window we are currently advertising.
732 * Rcv_nxt can be after the window if our peer push more data
733 * than the offered window.
735 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
737 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
744 /* Choose a new window, without checks for shrinking, and without
745 * scaling applied to the result. The caller does these things
746 * if necessary. This is a "raw" window selection.
748 u32 __tcp_select_window(struct sock *sk);
750 void tcp_send_window_probe(struct sock *sk);
752 /* TCP uses 32bit jiffies to save some space.
753 * Note that this is different from tcp_time_stamp, which
754 * historically has been the same until linux-4.13.
756 #define tcp_jiffies32 ((u32)jiffies)
759 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
760 * It is no longer tied to jiffies, but to 1 ms clock.
761 * Note: double check if you want to use tcp_jiffies32 instead of this.
763 #define TCP_TS_HZ 1000
765 static inline u64 tcp_clock_ns(void)
767 return ktime_get_ns();
770 static inline u64 tcp_clock_us(void)
772 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
775 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
776 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
778 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
781 /* Convert a nsec timestamp into TCP TSval timestamp (ms based currently) */
782 static inline u32 tcp_ns_to_ts(u64 ns)
784 return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ);
787 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
788 static inline u32 tcp_time_stamp_raw(void)
790 return tcp_ns_to_ts(tcp_clock_ns());
793 void tcp_mstamp_refresh(struct tcp_sock *tp);
795 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
797 return max_t(s64, t1 - t0, 0);
800 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
802 return tcp_ns_to_ts(skb->skb_mstamp_ns);
805 /* provide the departure time in us unit */
806 static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
808 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
812 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
814 #define TCPHDR_FIN 0x01
815 #define TCPHDR_SYN 0x02
816 #define TCPHDR_RST 0x04
817 #define TCPHDR_PSH 0x08
818 #define TCPHDR_ACK 0x10
819 #define TCPHDR_URG 0x20
820 #define TCPHDR_ECE 0x40
821 #define TCPHDR_CWR 0x80
823 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
825 /* This is what the send packet queuing engine uses to pass
826 * TCP per-packet control information to the transmission code.
827 * We also store the host-order sequence numbers in here too.
828 * This is 44 bytes if IPV6 is enabled.
829 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
832 __u32 seq; /* Starting sequence number */
833 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
835 /* Note : tcp_tw_isn is used in input path only
836 * (isn chosen by tcp_timewait_state_process())
838 * tcp_gso_segs/size are used in write queue only,
839 * cf tcp_skb_pcount()/tcp_skb_mss()
847 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
849 __u8 sacked; /* State flags for SACK. */
850 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
851 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
852 #define TCPCB_LOST 0x04 /* SKB is lost */
853 #define TCPCB_TAGBITS 0x07 /* All tag bits */
854 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */
855 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
856 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
859 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
860 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
861 eor:1, /* Is skb MSG_EOR marked? */
862 has_rxtstamp:1, /* SKB has a RX timestamp */
864 __u32 ack_seq; /* Sequence number ACK'd */
867 /* There is space for up to 24 bytes */
868 __u32 in_flight:30,/* Bytes in flight at transmit */
869 is_app_limited:1, /* cwnd not fully used? */
871 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
873 /* start of send pipeline phase */
875 /* when we reached the "delivered" count */
876 u64 delivered_mstamp;
877 } tx; /* only used for outgoing skbs */
879 struct inet_skb_parm h4;
880 #if IS_ENABLED(CONFIG_IPV6)
881 struct inet6_skb_parm h6;
883 } header; /* For incoming skbs */
886 struct sock *sk_redir;
892 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
894 static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
896 TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
899 static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb)
901 return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS;
904 static inline struct sock *tcp_skb_bpf_redirect_fetch(struct sk_buff *skb)
906 return TCP_SKB_CB(skb)->bpf.sk_redir;
909 static inline void tcp_skb_bpf_redirect_clear(struct sk_buff *skb)
911 TCP_SKB_CB(skb)->bpf.sk_redir = NULL;
914 extern const struct inet_connection_sock_af_ops ipv4_specific;
916 #if IS_ENABLED(CONFIG_IPV6)
917 /* This is the variant of inet6_iif() that must be used by TCP,
918 * as TCP moves IP6CB into a different location in skb->cb[]
920 static inline int tcp_v6_iif(const struct sk_buff *skb)
922 return TCP_SKB_CB(skb)->header.h6.iif;
925 static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
927 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
929 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
932 /* TCP_SKB_CB reference means this can not be used from early demux */
933 static inline int tcp_v6_sdif(const struct sk_buff *skb)
935 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
936 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
937 return TCP_SKB_CB(skb)->header.h6.iif;
942 extern const struct inet_connection_sock_af_ops ipv6_specific;
944 INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
945 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
946 INDIRECT_CALLABLE_DECLARE(void tcp_v6_early_demux(struct sk_buff *skb));
950 /* TCP_SKB_CB reference means this can not be used from early demux */
951 static inline int tcp_v4_sdif(struct sk_buff *skb)
953 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
954 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
955 return TCP_SKB_CB(skb)->header.h4.iif;
960 /* Due to TSO, an SKB can be composed of multiple actual
961 * packets. To keep these tracked properly, we use this.
963 static inline int tcp_skb_pcount(const struct sk_buff *skb)
965 return TCP_SKB_CB(skb)->tcp_gso_segs;
968 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
970 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
973 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
975 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
978 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
979 static inline int tcp_skb_mss(const struct sk_buff *skb)
981 return TCP_SKB_CB(skb)->tcp_gso_size;
984 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
986 return likely(!TCP_SKB_CB(skb)->eor);
989 static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
990 const struct sk_buff *from)
992 return likely(tcp_skb_can_collapse_to(to) &&
993 mptcp_skb_can_collapse(to, from));
996 /* Events passed to congestion control interface */
998 CA_EVENT_TX_START, /* first transmit when no packets in flight */
999 CA_EVENT_CWND_RESTART, /* congestion window restart */
1000 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
1001 CA_EVENT_LOSS, /* loss timeout */
1002 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
1003 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
1006 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1007 enum tcp_ca_ack_event_flags {
1008 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
1009 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
1010 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
1014 * Interface for adding new TCP congestion control handlers
1016 #define TCP_CA_NAME_MAX 16
1017 #define TCP_CA_MAX 128
1018 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
1020 #define TCP_CA_UNSPEC 0
1022 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1023 #define TCP_CONG_NON_RESTRICTED 0x1
1024 /* Requires ECN/ECT set on all packets */
1025 #define TCP_CONG_NEEDS_ECN 0x2
1026 #define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
1036 /* A rate sample measures the number of (original/retransmitted) data
1037 * packets delivered "delivered" over an interval of time "interval_us".
1038 * The tcp_rate.c code fills in the rate sample, and congestion
1039 * control modules that define a cong_control function to run at the end
1040 * of ACK processing can optionally chose to consult this sample when
1041 * setting cwnd and pacing rate.
1042 * A sample is invalid if "delivered" or "interval_us" is negative.
1044 struct rate_sample {
1045 u64 prior_mstamp; /* starting timestamp for interval */
1046 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1047 s32 delivered; /* number of packets delivered over interval */
1048 long interval_us; /* time for tp->delivered to incr "delivered" */
1049 u32 snd_interval_us; /* snd interval for delivered packets */
1050 u32 rcv_interval_us; /* rcv interval for delivered packets */
1051 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1052 int losses; /* number of packets marked lost upon ACK */
1053 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1054 u32 prior_in_flight; /* in flight before this ACK */
1055 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1056 bool is_retrans; /* is sample from retransmission? */
1057 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1060 struct tcp_congestion_ops {
1061 struct list_head list;
1065 /* initialize private data (optional) */
1066 void (*init)(struct sock *sk);
1067 /* cleanup private data (optional) */
1068 void (*release)(struct sock *sk);
1070 /* return slow start threshold (required) */
1071 u32 (*ssthresh)(struct sock *sk);
1072 /* do new cwnd calculation (required) */
1073 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1074 /* call before changing ca_state (optional) */
1075 void (*set_state)(struct sock *sk, u8 new_state);
1076 /* call when cwnd event occurs (optional) */
1077 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1078 /* call when ack arrives (optional) */
1079 void (*in_ack_event)(struct sock *sk, u32 flags);
1080 /* new value of cwnd after loss (required) */
1081 u32 (*undo_cwnd)(struct sock *sk);
1082 /* hook for packet ack accounting (optional) */
1083 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1084 /* override sysctl_tcp_min_tso_segs */
1085 u32 (*min_tso_segs)(struct sock *sk);
1086 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1087 u32 (*sndbuf_expand)(struct sock *sk);
1088 /* call when packets are delivered to update cwnd and pacing rate,
1089 * after all the ca_state processing. (optional)
1091 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1092 /* get info for inet_diag (optional) */
1093 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1094 union tcp_cc_info *info);
1096 char name[TCP_CA_NAME_MAX];
1097 struct module *owner;
1100 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1101 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1103 void tcp_assign_congestion_control(struct sock *sk);
1104 void tcp_init_congestion_control(struct sock *sk);
1105 void tcp_cleanup_congestion_control(struct sock *sk);
1106 int tcp_set_default_congestion_control(struct net *net, const char *name);
1107 void tcp_get_default_congestion_control(struct net *net, char *name);
1108 void tcp_get_available_congestion_control(char *buf, size_t len);
1109 void tcp_get_allowed_congestion_control(char *buf, size_t len);
1110 int tcp_set_allowed_congestion_control(char *allowed);
1111 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1112 bool cap_net_admin);
1113 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1114 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1116 u32 tcp_reno_ssthresh(struct sock *sk);
1117 u32 tcp_reno_undo_cwnd(struct sock *sk);
1118 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1119 extern struct tcp_congestion_ops tcp_reno;
1121 struct tcp_congestion_ops *tcp_ca_find(const char *name);
1122 struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1123 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1125 char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1127 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1133 static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1135 const struct inet_connection_sock *icsk = inet_csk(sk);
1137 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1140 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1142 struct inet_connection_sock *icsk = inet_csk(sk);
1144 if (icsk->icsk_ca_ops->set_state)
1145 icsk->icsk_ca_ops->set_state(sk, ca_state);
1146 icsk->icsk_ca_state = ca_state;
1149 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1151 const struct inet_connection_sock *icsk = inet_csk(sk);
1153 if (icsk->icsk_ca_ops->cwnd_event)
1154 icsk->icsk_ca_ops->cwnd_event(sk, event);
1157 /* From tcp_rate.c */
1158 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1159 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1160 struct rate_sample *rs);
1161 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1162 bool is_sack_reneg, struct rate_sample *rs);
1163 void tcp_rate_check_app_limited(struct sock *sk);
1165 /* These functions determine how the current flow behaves in respect of SACK
1166 * handling. SACK is negotiated with the peer, and therefore it can vary
1167 * between different flows.
1169 * tcp_is_sack - SACK enabled
1170 * tcp_is_reno - No SACK
1172 static inline int tcp_is_sack(const struct tcp_sock *tp)
1174 return likely(tp->rx_opt.sack_ok);
1177 static inline bool tcp_is_reno(const struct tcp_sock *tp)
1179 return !tcp_is_sack(tp);
1182 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1184 return tp->sacked_out + tp->lost_out;
1187 /* This determines how many packets are "in the network" to the best
1188 * of our knowledge. In many cases it is conservative, but where
1189 * detailed information is available from the receiver (via SACK
1190 * blocks etc.) we can make more aggressive calculations.
1192 * Use this for decisions involving congestion control, use just
1193 * tp->packets_out to determine if the send queue is empty or not.
1195 * Read this equation as:
1197 * "Packets sent once on transmission queue" MINUS
1198 * "Packets left network, but not honestly ACKed yet" PLUS
1199 * "Packets fast retransmitted"
1201 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1203 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1206 #define TCP_INFINITE_SSTHRESH 0x7fffffff
1208 static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1210 return tp->snd_cwnd < tp->snd_ssthresh;
1213 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1215 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1218 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1220 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1221 (1 << inet_csk(sk)->icsk_ca_state);
1224 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1225 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1228 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1230 const struct tcp_sock *tp = tcp_sk(sk);
1232 if (tcp_in_cwnd_reduction(sk))
1233 return tp->snd_ssthresh;
1235 return max(tp->snd_ssthresh,
1236 ((tp->snd_cwnd >> 1) +
1237 (tp->snd_cwnd >> 2)));
1240 /* Use define here intentionally to get WARN_ON location shown at the caller */
1241 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1243 void tcp_enter_cwr(struct sock *sk);
1244 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1246 /* The maximum number of MSS of available cwnd for which TSO defers
1247 * sending if not using sysctl_tcp_tso_win_divisor.
1249 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1254 /* Returns end sequence number of the receiver's advertised window */
1255 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1257 return tp->snd_una + tp->snd_wnd;
1260 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1261 * flexible approach. The RFC suggests cwnd should not be raised unless
1262 * it was fully used previously. And that's exactly what we do in
1263 * congestion avoidance mode. But in slow start we allow cwnd to grow
1264 * as long as the application has used half the cwnd.
1266 * cwnd is 10 (IW10), but application sends 9 frames.
1267 * We allow cwnd to reach 18 when all frames are ACKed.
1268 * This check is safe because it's as aggressive as slow start which already
1269 * risks 100% overshoot. The advantage is that we discourage application to
1270 * either send more filler packets or data to artificially blow up the cwnd
1271 * usage, and allow application-limited process to probe bw more aggressively.
1273 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1275 const struct tcp_sock *tp = tcp_sk(sk);
1277 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1278 if (tcp_in_slow_start(tp))
1279 return tp->snd_cwnd < 2 * tp->max_packets_out;
1281 return tp->is_cwnd_limited;
1284 /* BBR congestion control needs pacing.
1285 * Same remark for SO_MAX_PACING_RATE.
1286 * sch_fq packet scheduler is efficiently handling pacing,
1287 * but is not always installed/used.
1288 * Return true if TCP stack should pace packets itself.
1290 static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1292 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1295 /* Estimates in how many jiffies next packet for this flow can be sent.
1296 * Scheduling a retransmit timer too early would be silly.
1298 static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1300 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1302 return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1305 static inline void tcp_reset_xmit_timer(struct sock *sk,
1308 const unsigned long max_when)
1310 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1314 /* Something is really bad, we could not queue an additional packet,
1315 * because qdisc is full or receiver sent a 0 window, or we are paced.
1316 * We do not want to add fuel to the fire, or abort too early,
1317 * so make sure the timer we arm now is at least 200ms in the future,
1318 * regardless of current icsk_rto value (as it could be ~2ms)
1320 static inline unsigned long tcp_probe0_base(const struct sock *sk)
1322 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1325 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1326 static inline unsigned long tcp_probe0_when(const struct sock *sk,
1327 unsigned long max_when)
1329 u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1,
1330 inet_csk(sk)->icsk_backoff);
1331 u64 when = (u64)tcp_probe0_base(sk) << backoff;
1333 return (unsigned long)min_t(u64, when, max_when);
1336 static inline void tcp_check_probe_timer(struct sock *sk)
1338 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1339 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1340 tcp_probe0_base(sk), TCP_RTO_MAX);
1343 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1348 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1354 * Calculate(/check) TCP checksum
1356 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1357 __be32 daddr, __wsum base)
1359 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1362 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1364 return !skb_csum_unnecessary(skb) &&
1365 __skb_checksum_complete(skb);
1368 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1369 int tcp_filter(struct sock *sk, struct sk_buff *skb);
1370 void tcp_set_state(struct sock *sk, int state);
1371 void tcp_done(struct sock *sk);
1372 int tcp_abort(struct sock *sk, int err);
1374 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1377 rx_opt->num_sacks = 0;
1380 void tcp_cwnd_restart(struct sock *sk, s32 delta);
1382 static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1384 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1385 struct tcp_sock *tp = tcp_sk(sk);
1388 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1389 ca_ops->cong_control)
1391 delta = tcp_jiffies32 - tp->lsndtime;
1392 if (delta > inet_csk(sk)->icsk_rto)
1393 tcp_cwnd_restart(sk, delta);
1396 /* Determine a window scaling and initial window to offer. */
1397 void tcp_select_initial_window(const struct sock *sk, int __space,
1398 __u32 mss, __u32 *rcv_wnd,
1399 __u32 *window_clamp, int wscale_ok,
1400 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1402 static inline int tcp_win_from_space(const struct sock *sk, int space)
1404 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1406 return tcp_adv_win_scale <= 0 ?
1407 (space>>(-tcp_adv_win_scale)) :
1408 space - (space>>tcp_adv_win_scale);
1411 /* Note: caller must be prepared to deal with negative returns */
1412 static inline int tcp_space(const struct sock *sk)
1414 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1415 READ_ONCE(sk->sk_backlog.len) -
1416 atomic_read(&sk->sk_rmem_alloc));
1419 static inline int tcp_full_space(const struct sock *sk)
1421 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1424 void tcp_cleanup_rbuf(struct sock *sk, int copied);
1426 /* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1427 * If 87.5 % (7/8) of the space has been consumed, we want to override
1428 * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1429 * len/truesize ratio.
1431 static inline bool tcp_rmem_pressure(const struct sock *sk)
1433 int rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1434 int threshold = rcvbuf - (rcvbuf >> 3);
1436 return atomic_read(&sk->sk_rmem_alloc) > threshold;
1439 extern void tcp_openreq_init_rwin(struct request_sock *req,
1440 const struct sock *sk_listener,
1441 const struct dst_entry *dst);
1443 void tcp_enter_memory_pressure(struct sock *sk);
1444 void tcp_leave_memory_pressure(struct sock *sk);
1446 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1448 struct net *net = sock_net((struct sock *)tp);
1450 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1453 static inline int keepalive_time_when(const struct tcp_sock *tp)
1455 struct net *net = sock_net((struct sock *)tp);
1457 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1460 static inline int keepalive_probes(const struct tcp_sock *tp)
1462 struct net *net = sock_net((struct sock *)tp);
1464 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1467 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1469 const struct inet_connection_sock *icsk = &tp->inet_conn;
1471 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1472 tcp_jiffies32 - tp->rcv_tstamp);
1475 static inline int tcp_fin_time(const struct sock *sk)
1477 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1478 const int rto = inet_csk(sk)->icsk_rto;
1480 if (fin_timeout < (rto << 2) - (rto >> 1))
1481 fin_timeout = (rto << 2) - (rto >> 1);
1486 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1489 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1491 if (unlikely(!time_before32(ktime_get_seconds(),
1492 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1495 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1496 * then following tcp messages have valid values. Ignore 0 value,
1497 * or else 'negative' tsval might forbid us to accept their packets.
1499 if (!rx_opt->ts_recent)
1504 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1507 if (tcp_paws_check(rx_opt, 0))
1510 /* RST segments are not recommended to carry timestamp,
1511 and, if they do, it is recommended to ignore PAWS because
1512 "their cleanup function should take precedence over timestamps."
1513 Certainly, it is mistake. It is necessary to understand the reasons
1514 of this constraint to relax it: if peer reboots, clock may go
1515 out-of-sync and half-open connections will not be reset.
1516 Actually, the problem would be not existing if all
1517 the implementations followed draft about maintaining clock
1518 via reboots. Linux-2.2 DOES NOT!
1520 However, we can relax time bounds for RST segments to MSL.
1522 if (rst && !time_before32(ktime_get_seconds(),
1523 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1528 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1529 int mib_idx, u32 *last_oow_ack_time);
1531 static inline void tcp_mib_init(struct net *net)
1534 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1535 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1536 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1537 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1541 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1543 tp->lost_skb_hint = NULL;
1546 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1548 tcp_clear_retrans_hints_partial(tp);
1549 tp->retransmit_skb_hint = NULL;
1552 union tcp_md5_addr {
1554 #if IS_ENABLED(CONFIG_IPV6)
1559 /* - key database */
1560 struct tcp_md5sig_key {
1561 struct hlist_node node;
1563 u8 family; /* AF_INET or AF_INET6 */
1565 union tcp_md5_addr addr;
1566 int l3index; /* set if key added with L3 scope */
1567 u8 key[TCP_MD5SIG_MAXKEYLEN];
1568 struct rcu_head rcu;
1572 struct tcp_md5sig_info {
1573 struct hlist_head head;
1574 struct rcu_head rcu;
1577 /* - pseudo header */
1578 struct tcp4_pseudohdr {
1586 struct tcp6_pseudohdr {
1587 struct in6_addr saddr;
1588 struct in6_addr daddr;
1590 __be32 protocol; /* including padding */
1593 union tcp_md5sum_block {
1594 struct tcp4_pseudohdr ip4;
1595 #if IS_ENABLED(CONFIG_IPV6)
1596 struct tcp6_pseudohdr ip6;
1600 /* - pool: digest algorithm, hash description and scratch buffer */
1601 struct tcp_md5sig_pool {
1602 struct ahash_request *md5_req;
1607 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1608 const struct sock *sk, const struct sk_buff *skb);
1609 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1610 int family, u8 prefixlen, int l3index,
1611 const u8 *newkey, u8 newkeylen, gfp_t gfp);
1612 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1613 int family, u8 prefixlen, int l3index);
1614 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1615 const struct sock *addr_sk);
1617 #ifdef CONFIG_TCP_MD5SIG
1618 #include <linux/jump_label.h>
1619 extern struct static_key_false tcp_md5_needed;
1620 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1621 const union tcp_md5_addr *addr,
1623 static inline struct tcp_md5sig_key *
1624 tcp_md5_do_lookup(const struct sock *sk, int l3index,
1625 const union tcp_md5_addr *addr, int family)
1627 if (!static_branch_unlikely(&tcp_md5_needed))
1629 return __tcp_md5_do_lookup(sk, l3index, addr, family);
1632 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1634 static inline struct tcp_md5sig_key *
1635 tcp_md5_do_lookup(const struct sock *sk, int l3index,
1636 const union tcp_md5_addr *addr, int family)
1640 #define tcp_twsk_md5_key(twsk) NULL
1643 bool tcp_alloc_md5sig_pool(void);
1645 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1646 static inline void tcp_put_md5sig_pool(void)
1651 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1652 unsigned int header_len);
1653 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1654 const struct tcp_md5sig_key *key);
1656 /* From tcp_fastopen.c */
1657 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1658 struct tcp_fastopen_cookie *cookie);
1659 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1660 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1662 struct tcp_fastopen_request {
1663 /* Fast Open cookie. Size 0 means a cookie request */
1664 struct tcp_fastopen_cookie cookie;
1665 struct msghdr *data; /* data in MSG_FASTOPEN */
1667 int copied; /* queued in tcp_connect() */
1668 struct ubuf_info *uarg;
1670 void tcp_free_fastopen_req(struct tcp_sock *tp);
1671 void tcp_fastopen_destroy_cipher(struct sock *sk);
1672 void tcp_fastopen_ctx_destroy(struct net *net);
1673 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1674 void *primary_key, void *backup_key);
1675 int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1677 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1678 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1679 struct request_sock *req,
1680 struct tcp_fastopen_cookie *foc,
1681 const struct dst_entry *dst);
1682 void tcp_fastopen_init_key_once(struct net *net);
1683 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1684 struct tcp_fastopen_cookie *cookie);
1685 bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1686 #define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1687 #define TCP_FASTOPEN_KEY_MAX 2
1688 #define TCP_FASTOPEN_KEY_BUF_LENGTH \
1689 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1691 /* Fastopen key context */
1692 struct tcp_fastopen_context {
1693 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1695 struct rcu_head rcu;
1698 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1699 void tcp_fastopen_active_disable(struct sock *sk);
1700 bool tcp_fastopen_active_should_disable(struct sock *sk);
1701 void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1702 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1704 /* Caller needs to wrap with rcu_read_(un)lock() */
1706 struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1708 struct tcp_fastopen_context *ctx;
1710 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1712 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1717 bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1718 const struct tcp_fastopen_cookie *orig)
1720 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1721 orig->len == foc->len &&
1722 !memcmp(orig->val, foc->val, foc->len))
1728 int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1733 /* Latencies incurred by various limits for a sender. They are
1734 * chronograph-like stats that are mutually exclusive.
1738 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1739 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1740 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1744 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1745 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1747 /* This helper is needed, because skb->tcp_tsorted_anchor uses
1748 * the same memory storage than skb->destructor/_skb_refdst
1750 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1752 skb->destructor = NULL;
1753 skb->_skb_refdst = 0UL;
1756 #define tcp_skb_tsorted_save(skb) { \
1757 unsigned long _save = skb->_skb_refdst; \
1758 skb->_skb_refdst = 0UL;
1760 #define tcp_skb_tsorted_restore(skb) \
1761 skb->_skb_refdst = _save; \
1764 void tcp_write_queue_purge(struct sock *sk);
1766 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1768 return skb_rb_first(&sk->tcp_rtx_queue);
1771 static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1773 return skb_rb_last(&sk->tcp_rtx_queue);
1776 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1778 return skb_peek(&sk->sk_write_queue);
1781 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1783 return skb_peek_tail(&sk->sk_write_queue);
1786 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1787 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1789 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1791 return skb_peek(&sk->sk_write_queue);
1794 static inline bool tcp_skb_is_last(const struct sock *sk,
1795 const struct sk_buff *skb)
1797 return skb_queue_is_last(&sk->sk_write_queue, skb);
1801 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
1804 * Since the write queue can have a temporary empty skb in it,
1805 * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
1807 static inline bool tcp_write_queue_empty(const struct sock *sk)
1809 const struct tcp_sock *tp = tcp_sk(sk);
1811 return tp->write_seq == tp->snd_nxt;
1814 static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1816 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1819 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1821 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1824 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1826 __skb_queue_tail(&sk->sk_write_queue, skb);
1828 /* Queue it, remembering where we must start sending. */
1829 if (sk->sk_write_queue.next == skb)
1830 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1833 /* Insert new before skb on the write queue of sk. */
1834 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1835 struct sk_buff *skb,
1838 __skb_queue_before(&sk->sk_write_queue, skb, new);
1841 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1843 tcp_skb_tsorted_anchor_cleanup(skb);
1844 __skb_unlink(skb, &sk->sk_write_queue);
1847 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1849 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1851 tcp_skb_tsorted_anchor_cleanup(skb);
1852 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1855 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1857 list_del(&skb->tcp_tsorted_anchor);
1858 tcp_rtx_queue_unlink(skb, sk);
1859 sk_wmem_free_skb(sk, skb);
1862 static inline void tcp_push_pending_frames(struct sock *sk)
1864 if (tcp_send_head(sk)) {
1865 struct tcp_sock *tp = tcp_sk(sk);
1867 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1871 /* Start sequence of the skb just after the highest skb with SACKed
1872 * bit, valid only if sacked_out > 0 or when the caller has ensured
1873 * validity by itself.
1875 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1877 if (!tp->sacked_out)
1880 if (tp->highest_sack == NULL)
1883 return TCP_SKB_CB(tp->highest_sack)->seq;
1886 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1888 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1891 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1893 return tcp_sk(sk)->highest_sack;
1896 static inline void tcp_highest_sack_reset(struct sock *sk)
1898 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1901 /* Called when old skb is about to be deleted and replaced by new skb */
1902 static inline void tcp_highest_sack_replace(struct sock *sk,
1903 struct sk_buff *old,
1904 struct sk_buff *new)
1906 if (old == tcp_highest_sack(sk))
1907 tcp_sk(sk)->highest_sack = new;
1910 /* This helper checks if socket has IP_TRANSPARENT set */
1911 static inline bool inet_sk_transparent(const struct sock *sk)
1913 switch (sk->sk_state) {
1915 return inet_twsk(sk)->tw_transparent;
1916 case TCP_NEW_SYN_RECV:
1917 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1919 return inet_sk(sk)->transparent;
1922 /* Determines whether this is a thin stream (which may suffer from
1923 * increased latency). Used to trigger latency-reducing mechanisms.
1925 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1927 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1931 enum tcp_seq_states {
1932 TCP_SEQ_STATE_LISTENING,
1933 TCP_SEQ_STATE_ESTABLISHED,
1936 void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
1937 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
1938 void tcp_seq_stop(struct seq_file *seq, void *v);
1940 struct tcp_seq_afinfo {
1944 struct tcp_iter_state {
1945 struct seq_net_private p;
1946 enum tcp_seq_states state;
1947 struct sock *syn_wait_sk;
1948 struct tcp_seq_afinfo *bpf_seq_afinfo;
1949 int bucket, offset, sbucket, num;
1953 extern struct request_sock_ops tcp_request_sock_ops;
1954 extern struct request_sock_ops tcp6_request_sock_ops;
1956 void tcp_v4_destroy_sock(struct sock *sk);
1958 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1959 netdev_features_t features);
1960 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
1961 INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
1962 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
1963 INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
1964 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
1965 int tcp_gro_complete(struct sk_buff *skb);
1967 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1969 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1971 struct net *net = sock_net((struct sock *)tp);
1972 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1975 bool tcp_stream_memory_free(const struct sock *sk, int wake);
1977 #ifdef CONFIG_PROC_FS
1978 int tcp4_proc_init(void);
1979 void tcp4_proc_exit(void);
1982 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1983 int tcp_conn_request(struct request_sock_ops *rsk_ops,
1984 const struct tcp_request_sock_ops *af_ops,
1985 struct sock *sk, struct sk_buff *skb);
1987 /* TCP af-specific functions */
1988 struct tcp_sock_af_ops {
1989 #ifdef CONFIG_TCP_MD5SIG
1990 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1991 const struct sock *addr_sk);
1992 int (*calc_md5_hash)(char *location,
1993 const struct tcp_md5sig_key *md5,
1994 const struct sock *sk,
1995 const struct sk_buff *skb);
1996 int (*md5_parse)(struct sock *sk,
2003 struct tcp_request_sock_ops {
2005 #ifdef CONFIG_TCP_MD5SIG
2006 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2007 const struct sock *addr_sk);
2008 int (*calc_md5_hash) (char *location,
2009 const struct tcp_md5sig_key *md5,
2010 const struct sock *sk,
2011 const struct sk_buff *skb);
2013 #ifdef CONFIG_SYN_COOKIES
2014 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
2017 struct dst_entry *(*route_req)(const struct sock *sk,
2018 struct sk_buff *skb,
2020 struct request_sock *req);
2021 u32 (*init_seq)(const struct sk_buff *skb);
2022 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2023 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2024 struct flowi *fl, struct request_sock *req,
2025 struct tcp_fastopen_cookie *foc,
2026 enum tcp_synack_type synack_type,
2027 struct sk_buff *syn_skb);
2030 extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2031 #if IS_ENABLED(CONFIG_IPV6)
2032 extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2035 #ifdef CONFIG_SYN_COOKIES
2036 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2037 const struct sock *sk, struct sk_buff *skb,
2040 tcp_synq_overflow(sk);
2041 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2042 return ops->cookie_init_seq(skb, mss);
2045 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2046 const struct sock *sk, struct sk_buff *skb,
2053 int tcpv4_offload_init(void);
2055 void tcp_v4_init(void);
2056 void tcp_init(void);
2058 /* tcp_recovery.c */
2059 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2060 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2061 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2063 extern void tcp_rack_mark_lost(struct sock *sk);
2064 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2066 extern void tcp_rack_reo_timeout(struct sock *sk);
2067 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2069 /* At how many usecs into the future should the RTO fire? */
2070 static inline s64 tcp_rto_delta_us(const struct sock *sk)
2072 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2073 u32 rto = inet_csk(sk)->icsk_rto;
2074 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2076 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2080 * Save and compile IPv4 options, return a pointer to it
2082 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2083 struct sk_buff *skb)
2085 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2086 struct ip_options_rcu *dopt = NULL;
2089 int opt_size = sizeof(*dopt) + opt->optlen;
2091 dopt = kmalloc(opt_size, GFP_ATOMIC);
2092 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2100 /* locally generated TCP pure ACKs have skb->truesize == 2
2101 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2102 * This is much faster than dissecting the packet to find out.
2103 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2105 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2107 return skb->truesize == 2;
2110 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2115 static inline int tcp_inq(struct sock *sk)
2117 struct tcp_sock *tp = tcp_sk(sk);
2120 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2122 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2124 before(tp->urg_seq, tp->copied_seq) ||
2125 !before(tp->urg_seq, tp->rcv_nxt)) {
2127 answ = tp->rcv_nxt - tp->copied_seq;
2129 /* Subtract 1, if FIN was received */
2130 if (answ && sock_flag(sk, SOCK_DONE))
2133 answ = tp->urg_seq - tp->copied_seq;
2139 int tcp_peek_len(struct socket *sock);
2141 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2145 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2146 tp->segs_in += segs_in;
2147 if (skb->len > tcp_hdrlen(skb))
2148 tp->data_segs_in += segs_in;
2152 * TCP listen path runs lockless.
2153 * We forced "struct sock" to be const qualified to make sure
2154 * we don't modify one of its field by mistake.
2155 * Here, we increment sk_drops which is an atomic_t, so we can safely
2156 * make sock writable again.
2158 static inline void tcp_listendrop(const struct sock *sk)
2160 atomic_inc(&((struct sock *)sk)->sk_drops);
2161 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2164 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2167 * Interface for adding Upper Level Protocols over TCP
2170 #define TCP_ULP_NAME_MAX 16
2171 #define TCP_ULP_MAX 128
2172 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2174 struct tcp_ulp_ops {
2175 struct list_head list;
2177 /* initialize ulp */
2178 int (*init)(struct sock *sk);
2180 void (*update)(struct sock *sk, struct proto *p,
2181 void (*write_space)(struct sock *sk));
2183 void (*release)(struct sock *sk);
2185 int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2186 size_t (*get_info_size)(const struct sock *sk);
2188 void (*clone)(const struct request_sock *req, struct sock *newsk,
2189 const gfp_t priority);
2191 char name[TCP_ULP_NAME_MAX];
2192 struct module *owner;
2194 int tcp_register_ulp(struct tcp_ulp_ops *type);
2195 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2196 int tcp_set_ulp(struct sock *sk, const char *name);
2197 void tcp_get_available_ulp(char *buf, size_t len);
2198 void tcp_cleanup_ulp(struct sock *sk);
2199 void tcp_update_ulp(struct sock *sk, struct proto *p,
2200 void (*write_space)(struct sock *sk));
2202 #define MODULE_ALIAS_TCP_ULP(name) \
2203 __MODULE_INFO(alias, alias_userspace, name); \
2204 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2209 #ifdef CONFIG_BPF_STREAM_PARSER
2210 struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
2211 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2213 static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2216 #endif /* CONFIG_BPF_STREAM_PARSER */
2218 #ifdef CONFIG_NET_SOCK_MSG
2219 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
2221 int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
2222 struct msghdr *msg, int len, int flags);
2223 #endif /* CONFIG_NET_SOCK_MSG */
2225 #ifdef CONFIG_CGROUP_BPF
2226 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2227 struct sk_buff *skb,
2228 unsigned int end_offset)
2231 skops->skb_data_end = skb->data + end_offset;
2234 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2235 struct sk_buff *skb,
2236 unsigned int end_offset)
2241 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2242 * is < 0, then the BPF op failed (for example if the loaded BPF
2243 * program does not support the chosen operation or there is no BPF
2247 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2249 struct bpf_sock_ops_kern sock_ops;
2252 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2253 if (sk_fullsock(sk)) {
2254 sock_ops.is_fullsock = 1;
2255 sock_owned_by_me(sk);
2261 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2263 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2265 ret = sock_ops.reply;
2271 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2273 u32 args[2] = {arg1, arg2};
2275 return tcp_call_bpf(sk, op, 2, args);
2278 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2281 u32 args[3] = {arg1, arg2, arg3};
2283 return tcp_call_bpf(sk, op, 3, args);
2287 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2292 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2297 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2305 static inline u32 tcp_timeout_init(struct sock *sk)
2309 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2312 timeout = TCP_TIMEOUT_INIT;
2316 static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2320 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2327 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2329 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2332 static inline void tcp_bpf_rtt(struct sock *sk)
2334 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2335 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2338 #if IS_ENABLED(CONFIG_SMC)
2339 extern struct static_key_false tcp_have_smc;
2342 #if IS_ENABLED(CONFIG_TLS_DEVICE)
2343 void clean_acked_data_enable(struct inet_connection_sock *icsk,
2344 void (*cad)(struct sock *sk, u32 ack_seq));
2345 void clean_acked_data_disable(struct inet_connection_sock *icsk);
2346 void clean_acked_data_flush(void);
2349 DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2350 static inline void tcp_add_tx_delay(struct sk_buff *skb,
2351 const struct tcp_sock *tp)
2353 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2354 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2357 /* Compute Earliest Departure Time for some control packets
2358 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2360 static inline u64 tcp_transmit_time(const struct sock *sk)
2362 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2363 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2364 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2366 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;