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/cryptohash.h>
27 #include <linux/kref.h>
28 #include <linux/ktime.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>
43 #include <linux/seq_file.h>
44 #include <linux/memcontrol.h>
45 #include <linux/bpf-cgroup.h>
46 #include <linux/siphash.h>
48 extern struct inet_hashinfo tcp_hashinfo;
50 extern struct percpu_counter tcp_orphan_count;
51 void tcp_time_wait(struct sock *sk, int state, int timeo);
53 #define MAX_TCP_HEADER (128 + MAX_HEADER)
54 #define MAX_TCP_OPTION_SPACE 40
55 #define TCP_MIN_SND_MSS 48
56 #define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
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 initial 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];
246 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
247 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
248 #define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
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 READ_ONCE(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 int 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 void tcp_rcv_space_adjust(struct sock *sk);
339 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
340 void tcp_twsk_destructor(struct sock *sk);
341 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
342 struct pipe_inode_info *pipe, size_t len,
345 void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
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,
380 int tcp_child_process(struct sock *parent, struct sock *child,
381 struct sk_buff *skb);
382 void tcp_enter_loss(struct sock *sk);
383 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
384 void tcp_clear_retrans(struct tcp_sock *tp);
385 void tcp_update_metrics(struct sock *sk);
386 void tcp_init_metrics(struct sock *sk);
387 void tcp_metrics_init(void);
388 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
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 __poll_t 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 int tcp_set_rcvlowat(struct sock *sk, int val);
407 void tcp_data_ready(struct sock *sk);
409 int tcp_mmap(struct file *file, struct socket *sock,
410 struct vm_area_struct *vma);
412 void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
413 struct tcp_options_received *opt_rx,
414 int estab, struct tcp_fastopen_cookie *foc);
415 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
418 * BPF SKB-less helpers
420 u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
421 struct tcphdr *th, u32 *cookie);
422 u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
423 struct tcphdr *th, u32 *cookie);
424 u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
425 const struct tcp_request_sock_ops *af_ops,
426 struct sock *sk, struct tcphdr *th);
428 * TCP v4 functions exported for the inet6 API
431 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
432 void tcp_v4_mtu_reduced(struct sock *sk);
433 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
434 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
435 struct sock *tcp_create_openreq_child(const struct sock *sk,
436 struct request_sock *req,
437 struct sk_buff *skb);
438 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
439 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
440 struct request_sock *req,
441 struct dst_entry *dst,
442 struct request_sock *req_unhash,
444 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
445 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
446 int tcp_connect(struct sock *sk);
447 enum tcp_synack_type {
452 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
453 struct request_sock *req,
454 struct tcp_fastopen_cookie *foc,
455 enum tcp_synack_type synack_type);
456 int tcp_disconnect(struct sock *sk, int flags);
458 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
459 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
460 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
462 /* From syncookies.c */
463 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
464 struct request_sock *req,
465 struct dst_entry *dst, u32 tsoff);
466 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
468 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
469 #ifdef CONFIG_SYN_COOKIES
471 /* Syncookies use a monotonic timer which increments every 60 seconds.
472 * This counter is used both as a hash input and partially encoded into
473 * the cookie value. A cookie is only validated further if the delta
474 * between the current counter value and the encoded one is less than this,
475 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
476 * the counter advances immediately after a cookie is generated).
478 #define MAX_SYNCOOKIE_AGE 2
479 #define TCP_SYNCOOKIE_PERIOD (60 * HZ)
480 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
482 /* syncookies: remember time of last synqueue overflow
483 * But do not dirty this field too often (once per second is enough)
484 * It is racy as we do not hold a lock, but race is very minor.
486 static inline void tcp_synq_overflow(const struct sock *sk)
488 unsigned int last_overflow;
489 unsigned int now = jiffies;
491 if (sk->sk_reuseport) {
492 struct sock_reuseport *reuse;
494 reuse = rcu_dereference(sk->sk_reuseport_cb);
496 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
497 if (time_after32(now, last_overflow + HZ))
498 WRITE_ONCE(reuse->synq_overflow_ts, now);
503 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
504 if (time_after32(now, last_overflow + HZ))
505 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
508 /* syncookies: no recent synqueue overflow on this listening socket? */
509 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
511 unsigned int last_overflow;
512 unsigned int now = jiffies;
514 if (sk->sk_reuseport) {
515 struct sock_reuseport *reuse;
517 reuse = rcu_dereference(sk->sk_reuseport_cb);
519 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
520 return time_after32(now, last_overflow +
521 TCP_SYNCOOKIE_VALID);
525 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
526 return time_after32(now, last_overflow + TCP_SYNCOOKIE_VALID);
529 static inline u32 tcp_cookie_time(void)
531 u64 val = get_jiffies_64();
533 do_div(val, TCP_SYNCOOKIE_PERIOD);
537 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
539 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
540 u64 cookie_init_timestamp(struct request_sock *req);
541 bool cookie_timestamp_decode(const struct net *net,
542 struct tcp_options_received *opt);
543 bool cookie_ecn_ok(const struct tcp_options_received *opt,
544 const struct net *net, const struct dst_entry *dst);
546 /* From net/ipv6/syncookies.c */
547 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
549 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
551 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
552 const struct tcphdr *th, u16 *mssp);
553 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
557 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
559 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
560 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
561 void tcp_retransmit_timer(struct sock *sk);
562 void tcp_xmit_retransmit_queue(struct sock *);
563 void tcp_simple_retransmit(struct sock *);
564 void tcp_enter_recovery(struct sock *sk, bool ece_ack);
565 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
567 TCP_FRAG_IN_WRITE_QUEUE,
568 TCP_FRAG_IN_RTX_QUEUE,
570 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
571 struct sk_buff *skb, u32 len,
572 unsigned int mss_now, gfp_t gfp);
574 void tcp_send_probe0(struct sock *);
575 void tcp_send_partial(struct sock *);
576 int tcp_write_wakeup(struct sock *, int mib);
577 void tcp_send_fin(struct sock *sk);
578 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
579 int tcp_send_synack(struct sock *);
580 void tcp_push_one(struct sock *, unsigned int mss_now);
581 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
582 void tcp_send_ack(struct sock *sk);
583 void tcp_send_delayed_ack(struct sock *sk);
584 void tcp_send_loss_probe(struct sock *sk);
585 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
586 void tcp_skb_collapse_tstamp(struct sk_buff *skb,
587 const struct sk_buff *next_skb);
590 void tcp_rearm_rto(struct sock *sk);
591 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
592 void tcp_reset(struct sock *sk);
593 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
594 void tcp_fin(struct sock *sk);
597 void tcp_init_xmit_timers(struct sock *);
598 static inline void tcp_clear_xmit_timers(struct sock *sk)
600 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
603 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
606 inet_csk_clear_xmit_timers(sk);
609 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
610 unsigned int tcp_current_mss(struct sock *sk);
612 /* Bound MSS / TSO packet size with the half of the window */
613 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
617 /* When peer uses tiny windows, there is no use in packetizing
618 * to sub-MSS pieces for the sake of SWS or making sure there
619 * are enough packets in the pipe for fast recovery.
621 * On the other hand, for extremely large MSS devices, handling
622 * smaller than MSS windows in this way does make sense.
624 if (tp->max_window > TCP_MSS_DEFAULT)
625 cutoff = (tp->max_window >> 1);
627 cutoff = tp->max_window;
629 if (cutoff && pktsize > cutoff)
630 return max_t(int, cutoff, 68U - tp->tcp_header_len);
636 void tcp_get_info(struct sock *, struct tcp_info *);
638 /* Read 'sendfile()'-style from a TCP socket */
639 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
640 sk_read_actor_t recv_actor);
642 void tcp_initialize_rcv_mss(struct sock *sk);
644 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
645 int tcp_mss_to_mtu(struct sock *sk, int mss);
646 void tcp_mtup_init(struct sock *sk);
647 void tcp_init_buffer_space(struct sock *sk);
649 static inline void tcp_bound_rto(const struct sock *sk)
651 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
652 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
655 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
657 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
660 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
662 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
663 ntohl(TCP_FLAG_ACK) |
667 static inline void tcp_fast_path_on(struct tcp_sock *tp)
669 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
672 static inline void tcp_fast_path_check(struct sock *sk)
674 struct tcp_sock *tp = tcp_sk(sk);
676 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
678 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
680 tcp_fast_path_on(tp);
683 /* Compute the actual rto_min value */
684 static inline u32 tcp_rto_min(struct sock *sk)
686 const struct dst_entry *dst = __sk_dst_get(sk);
687 u32 rto_min = TCP_RTO_MIN;
689 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
690 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
694 static inline u32 tcp_rto_min_us(struct sock *sk)
696 return jiffies_to_usecs(tcp_rto_min(sk));
699 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
701 return dst_metric_locked(dst, RTAX_CC_ALGO);
704 /* Minimum RTT in usec. ~0 means not available. */
705 static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
707 return minmax_get(&tp->rtt_min);
710 /* Compute the actual receive window we are currently advertising.
711 * Rcv_nxt can be after the window if our peer push more data
712 * than the offered window.
714 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
716 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
723 /* Choose a new window, without checks for shrinking, and without
724 * scaling applied to the result. The caller does these things
725 * if necessary. This is a "raw" window selection.
727 u32 __tcp_select_window(struct sock *sk);
729 void tcp_send_window_probe(struct sock *sk);
731 /* TCP uses 32bit jiffies to save some space.
732 * Note that this is different from tcp_time_stamp, which
733 * historically has been the same until linux-4.13.
735 #define tcp_jiffies32 ((u32)jiffies)
738 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
739 * It is no longer tied to jiffies, but to 1 ms clock.
740 * Note: double check if you want to use tcp_jiffies32 instead of this.
742 #define TCP_TS_HZ 1000
744 static inline u64 tcp_clock_ns(void)
746 return ktime_get_ns();
749 static inline u64 tcp_clock_us(void)
751 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
754 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
755 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
757 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
760 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
761 static inline u32 tcp_time_stamp_raw(void)
763 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
766 void tcp_mstamp_refresh(struct tcp_sock *tp);
768 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
770 return max_t(s64, t1 - t0, 0);
773 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
775 return div_u64(skb->skb_mstamp_ns, NSEC_PER_SEC / TCP_TS_HZ);
778 /* provide the departure time in us unit */
779 static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
781 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
785 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
787 #define TCPHDR_FIN 0x01
788 #define TCPHDR_SYN 0x02
789 #define TCPHDR_RST 0x04
790 #define TCPHDR_PSH 0x08
791 #define TCPHDR_ACK 0x10
792 #define TCPHDR_URG 0x20
793 #define TCPHDR_ECE 0x40
794 #define TCPHDR_CWR 0x80
796 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
798 /* This is what the send packet queuing engine uses to pass
799 * TCP per-packet control information to the transmission code.
800 * We also store the host-order sequence numbers in here too.
801 * This is 44 bytes if IPV6 is enabled.
802 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
805 __u32 seq; /* Starting sequence number */
806 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
808 /* Note : tcp_tw_isn is used in input path only
809 * (isn chosen by tcp_timewait_state_process())
811 * tcp_gso_segs/size are used in write queue only,
812 * cf tcp_skb_pcount()/tcp_skb_mss()
820 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
822 __u8 sacked; /* State flags for SACK. */
823 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
824 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
825 #define TCPCB_LOST 0x04 /* SKB is lost */
826 #define TCPCB_TAGBITS 0x07 /* All tag bits */
827 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */
828 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
829 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
832 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
833 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
834 eor:1, /* Is skb MSG_EOR marked? */
835 has_rxtstamp:1, /* SKB has a RX timestamp */
837 __u32 ack_seq; /* Sequence number ACK'd */
840 /* There is space for up to 24 bytes */
841 __u32 in_flight:30,/* Bytes in flight at transmit */
842 is_app_limited:1, /* cwnd not fully used? */
844 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
846 /* start of send pipeline phase */
848 /* when we reached the "delivered" count */
849 u64 delivered_mstamp;
850 } tx; /* only used for outgoing skbs */
852 struct inet_skb_parm h4;
853 #if IS_ENABLED(CONFIG_IPV6)
854 struct inet6_skb_parm h6;
856 } header; /* For incoming skbs */
859 struct sock *sk_redir;
865 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
867 static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
869 TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
872 static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb)
874 return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS;
877 static inline struct sock *tcp_skb_bpf_redirect_fetch(struct sk_buff *skb)
879 return TCP_SKB_CB(skb)->bpf.sk_redir;
882 static inline void tcp_skb_bpf_redirect_clear(struct sk_buff *skb)
884 TCP_SKB_CB(skb)->bpf.sk_redir = NULL;
887 #if IS_ENABLED(CONFIG_IPV6)
888 /* This is the variant of inet6_iif() that must be used by TCP,
889 * as TCP moves IP6CB into a different location in skb->cb[]
891 static inline int tcp_v6_iif(const struct sk_buff *skb)
893 return TCP_SKB_CB(skb)->header.h6.iif;
896 static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
898 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
900 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
903 /* TCP_SKB_CB reference means this can not be used from early demux */
904 static inline int tcp_v6_sdif(const struct sk_buff *skb)
906 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
907 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
908 return TCP_SKB_CB(skb)->header.h6.iif;
914 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
916 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
917 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
918 skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
924 /* TCP_SKB_CB reference means this can not be used from early demux */
925 static inline int tcp_v4_sdif(struct sk_buff *skb)
927 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
928 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
929 return TCP_SKB_CB(skb)->header.h4.iif;
934 /* Due to TSO, an SKB can be composed of multiple actual
935 * packets. To keep these tracked properly, we use this.
937 static inline int tcp_skb_pcount(const struct sk_buff *skb)
939 return TCP_SKB_CB(skb)->tcp_gso_segs;
942 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
944 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
947 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
949 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
952 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
953 static inline int tcp_skb_mss(const struct sk_buff *skb)
955 return TCP_SKB_CB(skb)->tcp_gso_size;
958 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
960 return likely(!TCP_SKB_CB(skb)->eor);
963 /* Events passed to congestion control interface */
965 CA_EVENT_TX_START, /* first transmit when no packets in flight */
966 CA_EVENT_CWND_RESTART, /* congestion window restart */
967 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
968 CA_EVENT_LOSS, /* loss timeout */
969 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
970 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
973 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
974 enum tcp_ca_ack_event_flags {
975 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
976 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
977 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
981 * Interface for adding new TCP congestion control handlers
983 #define TCP_CA_NAME_MAX 16
984 #define TCP_CA_MAX 128
985 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
987 #define TCP_CA_UNSPEC 0
989 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
990 #define TCP_CONG_NON_RESTRICTED 0x1
991 /* Requires ECN/ECT set on all packets */
992 #define TCP_CONG_NEEDS_ECN 0x2
1002 /* A rate sample measures the number of (original/retransmitted) data
1003 * packets delivered "delivered" over an interval of time "interval_us".
1004 * The tcp_rate.c code fills in the rate sample, and congestion
1005 * control modules that define a cong_control function to run at the end
1006 * of ACK processing can optionally chose to consult this sample when
1007 * setting cwnd and pacing rate.
1008 * A sample is invalid if "delivered" or "interval_us" is negative.
1010 struct rate_sample {
1011 u64 prior_mstamp; /* starting timestamp for interval */
1012 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1013 s32 delivered; /* number of packets delivered over interval */
1014 long interval_us; /* time for tp->delivered to incr "delivered" */
1015 u32 snd_interval_us; /* snd interval for delivered packets */
1016 u32 rcv_interval_us; /* rcv interval for delivered packets */
1017 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1018 int losses; /* number of packets marked lost upon ACK */
1019 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1020 u32 prior_in_flight; /* in flight before this ACK */
1021 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1022 bool is_retrans; /* is sample from retransmission? */
1023 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1026 struct tcp_congestion_ops {
1027 struct list_head list;
1031 /* initialize private data (optional) */
1032 void (*init)(struct sock *sk);
1033 /* cleanup private data (optional) */
1034 void (*release)(struct sock *sk);
1036 /* return slow start threshold (required) */
1037 u32 (*ssthresh)(struct sock *sk);
1038 /* do new cwnd calculation (required) */
1039 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1040 /* call before changing ca_state (optional) */
1041 void (*set_state)(struct sock *sk, u8 new_state);
1042 /* call when cwnd event occurs (optional) */
1043 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1044 /* call when ack arrives (optional) */
1045 void (*in_ack_event)(struct sock *sk, u32 flags);
1046 /* new value of cwnd after loss (required) */
1047 u32 (*undo_cwnd)(struct sock *sk);
1048 /* hook for packet ack accounting (optional) */
1049 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1050 /* override sysctl_tcp_min_tso_segs */
1051 u32 (*min_tso_segs)(struct sock *sk);
1052 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1053 u32 (*sndbuf_expand)(struct sock *sk);
1054 /* call when packets are delivered to update cwnd and pacing rate,
1055 * after all the ca_state processing. (optional)
1057 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1058 /* get info for inet_diag (optional) */
1059 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1060 union tcp_cc_info *info);
1062 char name[TCP_CA_NAME_MAX];
1063 struct module *owner;
1066 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1067 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1069 void tcp_assign_congestion_control(struct sock *sk);
1070 void tcp_init_congestion_control(struct sock *sk);
1071 void tcp_cleanup_congestion_control(struct sock *sk);
1072 int tcp_set_default_congestion_control(struct net *net, const char *name);
1073 void tcp_get_default_congestion_control(struct net *net, char *name);
1074 void tcp_get_available_congestion_control(char *buf, size_t len);
1075 void tcp_get_allowed_congestion_control(char *buf, size_t len);
1076 int tcp_set_allowed_congestion_control(char *allowed);
1077 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1078 bool reinit, bool cap_net_admin);
1079 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1080 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1082 u32 tcp_reno_ssthresh(struct sock *sk);
1083 u32 tcp_reno_undo_cwnd(struct sock *sk);
1084 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1085 extern struct tcp_congestion_ops tcp_reno;
1087 struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1088 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1090 char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1092 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1098 static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1100 const struct inet_connection_sock *icsk = inet_csk(sk);
1102 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1105 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1107 struct inet_connection_sock *icsk = inet_csk(sk);
1109 if (icsk->icsk_ca_ops->set_state)
1110 icsk->icsk_ca_ops->set_state(sk, ca_state);
1111 icsk->icsk_ca_state = ca_state;
1114 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1116 const struct inet_connection_sock *icsk = inet_csk(sk);
1118 if (icsk->icsk_ca_ops->cwnd_event)
1119 icsk->icsk_ca_ops->cwnd_event(sk, event);
1122 /* From tcp_rate.c */
1123 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1124 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1125 struct rate_sample *rs);
1126 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1127 bool is_sack_reneg, struct rate_sample *rs);
1128 void tcp_rate_check_app_limited(struct sock *sk);
1130 /* These functions determine how the current flow behaves in respect of SACK
1131 * handling. SACK is negotiated with the peer, and therefore it can vary
1132 * between different flows.
1134 * tcp_is_sack - SACK enabled
1135 * tcp_is_reno - No SACK
1137 static inline int tcp_is_sack(const struct tcp_sock *tp)
1139 return likely(tp->rx_opt.sack_ok);
1142 static inline bool tcp_is_reno(const struct tcp_sock *tp)
1144 return !tcp_is_sack(tp);
1147 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1149 return tp->sacked_out + tp->lost_out;
1152 /* This determines how many packets are "in the network" to the best
1153 * of our knowledge. In many cases it is conservative, but where
1154 * detailed information is available from the receiver (via SACK
1155 * blocks etc.) we can make more aggressive calculations.
1157 * Use this for decisions involving congestion control, use just
1158 * tp->packets_out to determine if the send queue is empty or not.
1160 * Read this equation as:
1162 * "Packets sent once on transmission queue" MINUS
1163 * "Packets left network, but not honestly ACKed yet" PLUS
1164 * "Packets fast retransmitted"
1166 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1168 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1171 #define TCP_INFINITE_SSTHRESH 0x7fffffff
1173 static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1175 return tp->snd_cwnd < tp->snd_ssthresh;
1178 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1180 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1183 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1185 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1186 (1 << inet_csk(sk)->icsk_ca_state);
1189 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1190 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1193 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1195 const struct tcp_sock *tp = tcp_sk(sk);
1197 if (tcp_in_cwnd_reduction(sk))
1198 return tp->snd_ssthresh;
1200 return max(tp->snd_ssthresh,
1201 ((tp->snd_cwnd >> 1) +
1202 (tp->snd_cwnd >> 2)));
1205 /* Use define here intentionally to get WARN_ON location shown at the caller */
1206 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1208 void tcp_enter_cwr(struct sock *sk);
1209 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1211 /* The maximum number of MSS of available cwnd for which TSO defers
1212 * sending if not using sysctl_tcp_tso_win_divisor.
1214 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1219 /* Returns end sequence number of the receiver's advertised window */
1220 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1222 return tp->snd_una + tp->snd_wnd;
1225 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1226 * flexible approach. The RFC suggests cwnd should not be raised unless
1227 * it was fully used previously. And that's exactly what we do in
1228 * congestion avoidance mode. But in slow start we allow cwnd to grow
1229 * as long as the application has used half the cwnd.
1231 * cwnd is 10 (IW10), but application sends 9 frames.
1232 * We allow cwnd to reach 18 when all frames are ACKed.
1233 * This check is safe because it's as aggressive as slow start which already
1234 * risks 100% overshoot. The advantage is that we discourage application to
1235 * either send more filler packets or data to artificially blow up the cwnd
1236 * usage, and allow application-limited process to probe bw more aggressively.
1238 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1240 const struct tcp_sock *tp = tcp_sk(sk);
1242 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1243 if (tcp_in_slow_start(tp))
1244 return tp->snd_cwnd < 2 * tp->max_packets_out;
1246 return tp->is_cwnd_limited;
1249 /* BBR congestion control needs pacing.
1250 * Same remark for SO_MAX_PACING_RATE.
1251 * sch_fq packet scheduler is efficiently handling pacing,
1252 * but is not always installed/used.
1253 * Return true if TCP stack should pace packets itself.
1255 static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1257 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1260 /* Return in jiffies the delay before one skb is sent.
1261 * If @skb is NULL, we look at EDT for next packet being sent on the socket.
1263 static inline unsigned long tcp_pacing_delay(const struct sock *sk,
1264 const struct sk_buff *skb)
1266 s64 pacing_delay = skb ? skb->tstamp : tcp_sk(sk)->tcp_wstamp_ns;
1268 pacing_delay -= tcp_sk(sk)->tcp_clock_cache;
1270 return pacing_delay > 0 ? nsecs_to_jiffies(pacing_delay) : 0;
1273 static inline void tcp_reset_xmit_timer(struct sock *sk,
1276 const unsigned long max_when,
1277 const struct sk_buff *skb)
1279 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk, skb),
1283 /* Something is really bad, we could not queue an additional packet,
1284 * because qdisc is full or receiver sent a 0 window, or we are paced.
1285 * We do not want to add fuel to the fire, or abort too early,
1286 * so make sure the timer we arm now is at least 200ms in the future,
1287 * regardless of current icsk_rto value (as it could be ~2ms)
1289 static inline unsigned long tcp_probe0_base(const struct sock *sk)
1291 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1294 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1295 static inline unsigned long tcp_probe0_when(const struct sock *sk,
1296 unsigned long max_when)
1298 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1300 return (unsigned long)min_t(u64, when, max_when);
1303 static inline void tcp_check_probe_timer(struct sock *sk)
1305 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1306 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1307 tcp_probe0_base(sk), TCP_RTO_MAX,
1311 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1316 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1322 * Calculate(/check) TCP checksum
1324 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1325 __be32 daddr, __wsum base)
1327 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1330 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1332 return !skb_csum_unnecessary(skb) &&
1333 __skb_checksum_complete(skb);
1336 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1337 int tcp_filter(struct sock *sk, struct sk_buff *skb);
1338 void tcp_set_state(struct sock *sk, int state);
1339 void tcp_done(struct sock *sk);
1340 int tcp_abort(struct sock *sk, int err);
1342 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1345 rx_opt->num_sacks = 0;
1348 u32 tcp_default_init_rwnd(u32 mss);
1349 void tcp_cwnd_restart(struct sock *sk, s32 delta);
1351 static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1353 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1354 struct tcp_sock *tp = tcp_sk(sk);
1357 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1358 ca_ops->cong_control)
1360 delta = tcp_jiffies32 - tp->lsndtime;
1361 if (delta > inet_csk(sk)->icsk_rto)
1362 tcp_cwnd_restart(sk, delta);
1365 /* Determine a window scaling and initial window to offer. */
1366 void tcp_select_initial_window(const struct sock *sk, int __space,
1367 __u32 mss, __u32 *rcv_wnd,
1368 __u32 *window_clamp, int wscale_ok,
1369 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1371 static inline int tcp_win_from_space(const struct sock *sk, int space)
1373 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1375 return tcp_adv_win_scale <= 0 ?
1376 (space>>(-tcp_adv_win_scale)) :
1377 space - (space>>tcp_adv_win_scale);
1380 /* Note: caller must be prepared to deal with negative returns */
1381 static inline int tcp_space(const struct sock *sk)
1383 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1384 READ_ONCE(sk->sk_backlog.len) -
1385 atomic_read(&sk->sk_rmem_alloc));
1388 static inline int tcp_full_space(const struct sock *sk)
1390 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1393 extern void tcp_openreq_init_rwin(struct request_sock *req,
1394 const struct sock *sk_listener,
1395 const struct dst_entry *dst);
1397 void tcp_enter_memory_pressure(struct sock *sk);
1398 void tcp_leave_memory_pressure(struct sock *sk);
1400 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1402 struct net *net = sock_net((struct sock *)tp);
1404 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1407 static inline int keepalive_time_when(const struct tcp_sock *tp)
1409 struct net *net = sock_net((struct sock *)tp);
1411 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1414 static inline int keepalive_probes(const struct tcp_sock *tp)
1416 struct net *net = sock_net((struct sock *)tp);
1418 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1421 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1423 const struct inet_connection_sock *icsk = &tp->inet_conn;
1425 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1426 tcp_jiffies32 - tp->rcv_tstamp);
1429 static inline int tcp_fin_time(const struct sock *sk)
1431 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1432 const int rto = inet_csk(sk)->icsk_rto;
1434 if (fin_timeout < (rto << 2) - (rto >> 1))
1435 fin_timeout = (rto << 2) - (rto >> 1);
1440 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1443 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1445 if (unlikely(!time_before32(ktime_get_seconds(),
1446 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1449 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1450 * then following tcp messages have valid values. Ignore 0 value,
1451 * or else 'negative' tsval might forbid us to accept their packets.
1453 if (!rx_opt->ts_recent)
1458 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1461 if (tcp_paws_check(rx_opt, 0))
1464 /* RST segments are not recommended to carry timestamp,
1465 and, if they do, it is recommended to ignore PAWS because
1466 "their cleanup function should take precedence over timestamps."
1467 Certainly, it is mistake. It is necessary to understand the reasons
1468 of this constraint to relax it: if peer reboots, clock may go
1469 out-of-sync and half-open connections will not be reset.
1470 Actually, the problem would be not existing if all
1471 the implementations followed draft about maintaining clock
1472 via reboots. Linux-2.2 DOES NOT!
1474 However, we can relax time bounds for RST segments to MSL.
1476 if (rst && !time_before32(ktime_get_seconds(),
1477 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1482 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1483 int mib_idx, u32 *last_oow_ack_time);
1485 static inline void tcp_mib_init(struct net *net)
1488 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1489 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1490 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1491 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1495 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1497 tp->lost_skb_hint = NULL;
1500 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1502 tcp_clear_retrans_hints_partial(tp);
1503 tp->retransmit_skb_hint = NULL;
1506 union tcp_md5_addr {
1508 #if IS_ENABLED(CONFIG_IPV6)
1513 /* - key database */
1514 struct tcp_md5sig_key {
1515 struct hlist_node node;
1517 u8 family; /* AF_INET or AF_INET6 */
1518 union tcp_md5_addr addr;
1520 u8 key[TCP_MD5SIG_MAXKEYLEN];
1521 struct rcu_head rcu;
1525 struct tcp_md5sig_info {
1526 struct hlist_head head;
1527 struct rcu_head rcu;
1530 /* - pseudo header */
1531 struct tcp4_pseudohdr {
1539 struct tcp6_pseudohdr {
1540 struct in6_addr saddr;
1541 struct in6_addr daddr;
1543 __be32 protocol; /* including padding */
1546 union tcp_md5sum_block {
1547 struct tcp4_pseudohdr ip4;
1548 #if IS_ENABLED(CONFIG_IPV6)
1549 struct tcp6_pseudohdr ip6;
1553 /* - pool: digest algorithm, hash description and scratch buffer */
1554 struct tcp_md5sig_pool {
1555 struct ahash_request *md5_req;
1560 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1561 const struct sock *sk, const struct sk_buff *skb);
1562 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1563 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
1565 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1566 int family, u8 prefixlen);
1567 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1568 const struct sock *addr_sk);
1570 #ifdef CONFIG_TCP_MD5SIG
1571 #include <linux/jump_label.h>
1572 extern struct static_key_false tcp_md5_needed;
1573 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk,
1574 const union tcp_md5_addr *addr,
1576 static inline struct tcp_md5sig_key *
1577 tcp_md5_do_lookup(const struct sock *sk,
1578 const union tcp_md5_addr *addr,
1581 if (!static_branch_unlikely(&tcp_md5_needed))
1583 return __tcp_md5_do_lookup(sk, addr, family);
1586 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1588 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1589 const union tcp_md5_addr *addr,
1594 #define tcp_twsk_md5_key(twsk) NULL
1597 bool tcp_alloc_md5sig_pool(void);
1599 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1600 static inline void tcp_put_md5sig_pool(void)
1605 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1606 unsigned int header_len);
1607 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1608 const struct tcp_md5sig_key *key);
1610 /* From tcp_fastopen.c */
1611 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1612 struct tcp_fastopen_cookie *cookie);
1613 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1614 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1616 struct tcp_fastopen_request {
1617 /* Fast Open cookie. Size 0 means a cookie request */
1618 struct tcp_fastopen_cookie cookie;
1619 struct msghdr *data; /* data in MSG_FASTOPEN */
1621 int copied; /* queued in tcp_connect() */
1622 struct ubuf_info *uarg;
1624 void tcp_free_fastopen_req(struct tcp_sock *tp);
1625 void tcp_fastopen_destroy_cipher(struct sock *sk);
1626 void tcp_fastopen_ctx_destroy(struct net *net);
1627 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1628 void *primary_key, void *backup_key);
1629 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1630 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1631 struct request_sock *req,
1632 struct tcp_fastopen_cookie *foc,
1633 const struct dst_entry *dst);
1634 void tcp_fastopen_init_key_once(struct net *net);
1635 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1636 struct tcp_fastopen_cookie *cookie);
1637 bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1638 #define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1639 #define TCP_FASTOPEN_KEY_MAX 2
1640 #define TCP_FASTOPEN_KEY_BUF_LENGTH \
1641 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1643 /* Fastopen key context */
1644 struct tcp_fastopen_context {
1645 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1647 struct rcu_head rcu;
1650 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1651 void tcp_fastopen_active_disable(struct sock *sk);
1652 bool tcp_fastopen_active_should_disable(struct sock *sk);
1653 void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1654 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1656 /* Caller needs to wrap with rcu_read_(un)lock() */
1658 struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1660 struct tcp_fastopen_context *ctx;
1662 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1664 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1669 bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1670 const struct tcp_fastopen_cookie *orig)
1672 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1673 orig->len == foc->len &&
1674 !memcmp(orig->val, foc->val, foc->len))
1680 int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1685 /* Latencies incurred by various limits for a sender. They are
1686 * chronograph-like stats that are mutually exclusive.
1690 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1691 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1692 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1696 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1697 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1699 /* This helper is needed, because skb->tcp_tsorted_anchor uses
1700 * the same memory storage than skb->destructor/_skb_refdst
1702 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1704 skb->destructor = NULL;
1705 skb->_skb_refdst = 0UL;
1708 #define tcp_skb_tsorted_save(skb) { \
1709 unsigned long _save = skb->_skb_refdst; \
1710 skb->_skb_refdst = 0UL;
1712 #define tcp_skb_tsorted_restore(skb) \
1713 skb->_skb_refdst = _save; \
1716 void tcp_write_queue_purge(struct sock *sk);
1718 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1720 return skb_rb_first(&sk->tcp_rtx_queue);
1723 static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1725 return skb_rb_last(&sk->tcp_rtx_queue);
1728 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1730 return skb_peek(&sk->sk_write_queue);
1733 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1735 return skb_peek_tail(&sk->sk_write_queue);
1738 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1739 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1741 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1743 return skb_peek(&sk->sk_write_queue);
1746 static inline bool tcp_skb_is_last(const struct sock *sk,
1747 const struct sk_buff *skb)
1749 return skb_queue_is_last(&sk->sk_write_queue, skb);
1752 static inline bool tcp_write_queue_empty(const struct sock *sk)
1754 return skb_queue_empty(&sk->sk_write_queue);
1757 static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1759 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1762 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1764 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1767 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1769 __skb_queue_tail(&sk->sk_write_queue, skb);
1771 /* Queue it, remembering where we must start sending. */
1772 if (sk->sk_write_queue.next == skb)
1773 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1776 /* Insert new before skb on the write queue of sk. */
1777 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1778 struct sk_buff *skb,
1781 __skb_queue_before(&sk->sk_write_queue, skb, new);
1784 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1786 tcp_skb_tsorted_anchor_cleanup(skb);
1787 __skb_unlink(skb, &sk->sk_write_queue);
1790 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1792 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1794 tcp_skb_tsorted_anchor_cleanup(skb);
1795 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1798 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1800 list_del(&skb->tcp_tsorted_anchor);
1801 tcp_rtx_queue_unlink(skb, sk);
1802 sk_wmem_free_skb(sk, skb);
1805 static inline void tcp_push_pending_frames(struct sock *sk)
1807 if (tcp_send_head(sk)) {
1808 struct tcp_sock *tp = tcp_sk(sk);
1810 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1814 /* Start sequence of the skb just after the highest skb with SACKed
1815 * bit, valid only if sacked_out > 0 or when the caller has ensured
1816 * validity by itself.
1818 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1820 if (!tp->sacked_out)
1823 if (tp->highest_sack == NULL)
1826 return TCP_SKB_CB(tp->highest_sack)->seq;
1829 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1831 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1834 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1836 return tcp_sk(sk)->highest_sack;
1839 static inline void tcp_highest_sack_reset(struct sock *sk)
1841 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1844 /* Called when old skb is about to be deleted and replaced by new skb */
1845 static inline void tcp_highest_sack_replace(struct sock *sk,
1846 struct sk_buff *old,
1847 struct sk_buff *new)
1849 if (old == tcp_highest_sack(sk))
1850 tcp_sk(sk)->highest_sack = new;
1853 /* This helper checks if socket has IP_TRANSPARENT set */
1854 static inline bool inet_sk_transparent(const struct sock *sk)
1856 switch (sk->sk_state) {
1858 return inet_twsk(sk)->tw_transparent;
1859 case TCP_NEW_SYN_RECV:
1860 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1862 return inet_sk(sk)->transparent;
1865 /* Determines whether this is a thin stream (which may suffer from
1866 * increased latency). Used to trigger latency-reducing mechanisms.
1868 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1870 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1874 enum tcp_seq_states {
1875 TCP_SEQ_STATE_LISTENING,
1876 TCP_SEQ_STATE_ESTABLISHED,
1879 void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
1880 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
1881 void tcp_seq_stop(struct seq_file *seq, void *v);
1883 struct tcp_seq_afinfo {
1887 struct tcp_iter_state {
1888 struct seq_net_private p;
1889 enum tcp_seq_states state;
1890 struct sock *syn_wait_sk;
1891 int bucket, offset, sbucket, num;
1895 extern struct request_sock_ops tcp_request_sock_ops;
1896 extern struct request_sock_ops tcp6_request_sock_ops;
1898 void tcp_v4_destroy_sock(struct sock *sk);
1900 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1901 netdev_features_t features);
1902 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
1903 int tcp_gro_complete(struct sk_buff *skb);
1905 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1907 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1909 struct net *net = sock_net((struct sock *)tp);
1910 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1913 /* @wake is one when sk_stream_write_space() calls us.
1914 * This sends EPOLLOUT only if notsent_bytes is half the limit.
1915 * This mimics the strategy used in sock_def_write_space().
1917 static inline bool tcp_stream_memory_free(const struct sock *sk, int wake)
1919 const struct tcp_sock *tp = tcp_sk(sk);
1920 u32 notsent_bytes = READ_ONCE(tp->write_seq) -
1921 READ_ONCE(tp->snd_nxt);
1923 return (notsent_bytes << wake) < tcp_notsent_lowat(tp);
1926 #ifdef CONFIG_PROC_FS
1927 int tcp4_proc_init(void);
1928 void tcp4_proc_exit(void);
1931 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1932 int tcp_conn_request(struct request_sock_ops *rsk_ops,
1933 const struct tcp_request_sock_ops *af_ops,
1934 struct sock *sk, struct sk_buff *skb);
1936 /* TCP af-specific functions */
1937 struct tcp_sock_af_ops {
1938 #ifdef CONFIG_TCP_MD5SIG
1939 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1940 const struct sock *addr_sk);
1941 int (*calc_md5_hash)(char *location,
1942 const struct tcp_md5sig_key *md5,
1943 const struct sock *sk,
1944 const struct sk_buff *skb);
1945 int (*md5_parse)(struct sock *sk,
1947 char __user *optval,
1952 struct tcp_request_sock_ops {
1954 #ifdef CONFIG_TCP_MD5SIG
1955 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1956 const struct sock *addr_sk);
1957 int (*calc_md5_hash) (char *location,
1958 const struct tcp_md5sig_key *md5,
1959 const struct sock *sk,
1960 const struct sk_buff *skb);
1962 void (*init_req)(struct request_sock *req,
1963 const struct sock *sk_listener,
1964 struct sk_buff *skb);
1965 #ifdef CONFIG_SYN_COOKIES
1966 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1969 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1970 const struct request_sock *req);
1971 u32 (*init_seq)(const struct sk_buff *skb);
1972 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1973 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1974 struct flowi *fl, struct request_sock *req,
1975 struct tcp_fastopen_cookie *foc,
1976 enum tcp_synack_type synack_type);
1979 #ifdef CONFIG_SYN_COOKIES
1980 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1981 const struct sock *sk, struct sk_buff *skb,
1984 tcp_synq_overflow(sk);
1985 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1986 return ops->cookie_init_seq(skb, mss);
1989 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1990 const struct sock *sk, struct sk_buff *skb,
1997 int tcpv4_offload_init(void);
1999 void tcp_v4_init(void);
2000 void tcp_init(void);
2002 /* tcp_recovery.c */
2003 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2004 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2005 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2007 extern void tcp_rack_mark_lost(struct sock *sk);
2008 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2010 extern void tcp_rack_reo_timeout(struct sock *sk);
2011 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2013 /* At how many usecs into the future should the RTO fire? */
2014 static inline s64 tcp_rto_delta_us(const struct sock *sk)
2016 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2017 u32 rto = inet_csk(sk)->icsk_rto;
2018 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2020 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2024 * Save and compile IPv4 options, return a pointer to it
2026 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2027 struct sk_buff *skb)
2029 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2030 struct ip_options_rcu *dopt = NULL;
2033 int opt_size = sizeof(*dopt) + opt->optlen;
2035 dopt = kmalloc(opt_size, GFP_ATOMIC);
2036 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2044 /* locally generated TCP pure ACKs have skb->truesize == 2
2045 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2046 * This is much faster than dissecting the packet to find out.
2047 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2049 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2051 return skb->truesize == 2;
2054 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2059 static inline int tcp_inq(struct sock *sk)
2061 struct tcp_sock *tp = tcp_sk(sk);
2064 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2066 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2068 before(tp->urg_seq, tp->copied_seq) ||
2069 !before(tp->urg_seq, tp->rcv_nxt)) {
2071 answ = tp->rcv_nxt - tp->copied_seq;
2073 /* Subtract 1, if FIN was received */
2074 if (answ && sock_flag(sk, SOCK_DONE))
2077 answ = tp->urg_seq - tp->copied_seq;
2083 int tcp_peek_len(struct socket *sock);
2085 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2089 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2090 tp->segs_in += segs_in;
2091 if (skb->len > tcp_hdrlen(skb))
2092 tp->data_segs_in += segs_in;
2096 * TCP listen path runs lockless.
2097 * We forced "struct sock" to be const qualified to make sure
2098 * we don't modify one of its field by mistake.
2099 * Here, we increment sk_drops which is an atomic_t, so we can safely
2100 * make sock writable again.
2102 static inline void tcp_listendrop(const struct sock *sk)
2104 atomic_inc(&((struct sock *)sk)->sk_drops);
2105 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2108 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2111 * Interface for adding Upper Level Protocols over TCP
2114 #define TCP_ULP_NAME_MAX 16
2115 #define TCP_ULP_MAX 128
2116 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2118 struct tcp_ulp_ops {
2119 struct list_head list;
2121 /* initialize ulp */
2122 int (*init)(struct sock *sk);
2124 void (*update)(struct sock *sk, struct proto *p);
2126 void (*release)(struct sock *sk);
2128 int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2129 size_t (*get_info_size)(const struct sock *sk);
2131 char name[TCP_ULP_NAME_MAX];
2132 struct module *owner;
2134 int tcp_register_ulp(struct tcp_ulp_ops *type);
2135 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2136 int tcp_set_ulp(struct sock *sk, const char *name);
2137 void tcp_get_available_ulp(char *buf, size_t len);
2138 void tcp_cleanup_ulp(struct sock *sk);
2139 void tcp_update_ulp(struct sock *sk, struct proto *p);
2141 #define MODULE_ALIAS_TCP_ULP(name) \
2142 __MODULE_INFO(alias, alias_userspace, name); \
2143 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2148 int tcp_bpf_init(struct sock *sk);
2149 void tcp_bpf_reinit(struct sock *sk);
2150 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
2152 int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
2153 int nonblock, int flags, int *addr_len);
2154 int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
2155 struct msghdr *msg, int len, int flags);
2157 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2158 * is < 0, then the BPF op failed (for example if the loaded BPF
2159 * program does not support the chosen operation or there is no BPF
2163 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2165 struct bpf_sock_ops_kern sock_ops;
2168 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2169 if (sk_fullsock(sk)) {
2170 sock_ops.is_fullsock = 1;
2171 sock_owned_by_me(sk);
2177 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2179 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2181 ret = sock_ops.reply;
2187 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2189 u32 args[2] = {arg1, arg2};
2191 return tcp_call_bpf(sk, op, 2, args);
2194 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2197 u32 args[3] = {arg1, arg2, arg3};
2199 return tcp_call_bpf(sk, op, 3, args);
2203 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2208 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2213 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2221 static inline u32 tcp_timeout_init(struct sock *sk)
2225 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2228 timeout = TCP_TIMEOUT_INIT;
2232 static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2236 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2243 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2245 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2248 static inline void tcp_bpf_rtt(struct sock *sk)
2250 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2251 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2254 #if IS_ENABLED(CONFIG_SMC)
2255 extern struct static_key_false tcp_have_smc;
2258 #if IS_ENABLED(CONFIG_TLS_DEVICE)
2259 void clean_acked_data_enable(struct inet_connection_sock *icsk,
2260 void (*cad)(struct sock *sk, u32 ack_seq));
2261 void clean_acked_data_disable(struct inet_connection_sock *icsk);
2262 void clean_acked_data_flush(void);
2265 DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2266 static inline void tcp_add_tx_delay(struct sk_buff *skb,
2267 const struct tcp_sock *tp)
2269 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2270 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2273 /* Compute Earliest Departure Time for some control packets
2274 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2276 static inline u64 tcp_transmit_time(const struct sock *sk)
2278 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2279 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2280 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2282 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;