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 DECLARE_PER_CPU(unsigned int, tcp_orphan_count);
52 int tcp_orphan_count_sum(void);
54 void tcp_time_wait(struct sock *sk, int state, int timeo);
56 #define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER)
57 #define MAX_TCP_OPTION_SPACE 40
58 #define TCP_MIN_SND_MSS 48
59 #define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
62 * Never offer a window over 32767 without using window scaling. Some
63 * poor stacks do signed 16bit maths!
65 #define MAX_TCP_WINDOW 32767U
67 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68 #define TCP_MIN_MSS 88U
70 /* The initial MTU to use for probing */
71 #define TCP_BASE_MSS 1024
73 /* probing interval, default to 10 minutes as per RFC4821 */
74 #define TCP_PROBE_INTERVAL 600
76 /* Specify interval when tcp mtu probing will stop */
77 #define TCP_PROBE_THRESHOLD 8
79 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
80 #define TCP_FASTRETRANS_THRESH 3
82 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
83 #define TCP_MAX_QUICKACKS 16U
85 /* Maximal number of window scale according to RFC1323 */
86 #define TCP_MAX_WSCALE 14U
89 #define TCP_URG_VALID 0x0100
90 #define TCP_URG_NOTYET 0x0200
91 #define TCP_URG_READ 0x0400
93 #define TCP_RETR1 3 /*
94 * This is how many retries it does before it
95 * tries to figure out if the gateway is
96 * down. Minimal RFC value is 3; it corresponds
97 * to ~3sec-8min depending on RTO.
100 #define TCP_RETR2 15 /*
101 * This should take at least
102 * 90 minutes to time out.
103 * RFC1122 says that the limit is 100 sec.
104 * 15 is ~13-30min depending on RTO.
107 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
108 * when active opening a connection.
109 * RFC1122 says the minimum retry MUST
110 * be at least 180secs. Nevertheless
111 * this value is corresponding to
112 * 63secs of retransmission with the
113 * current initial RTO.
116 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
117 * when passive opening a connection.
118 * This is corresponding to 31secs of
119 * retransmission with the current
123 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
124 * state, about 60 seconds */
125 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
126 /* BSD style FIN_WAIT2 deadlock breaker.
127 * It used to be 3min, new value is 60sec,
128 * to combine FIN-WAIT-2 timeout with
131 #define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
133 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
135 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
136 #define TCP_ATO_MIN ((unsigned)(HZ/25))
138 #define TCP_DELACK_MIN 4U
139 #define TCP_ATO_MIN 4U
141 #define TCP_RTO_MAX ((unsigned)(120*HZ))
142 #define TCP_RTO_MIN ((unsigned)(HZ/5))
143 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
144 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
145 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
146 * used as a fallback RTO for the
147 * initial data transmission if no
148 * valid RTT sample has been acquired,
149 * most likely due to retrans in 3WHS.
152 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
153 * for local resources.
155 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
156 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
157 #define TCP_KEEPALIVE_INTVL (75*HZ)
159 #define MAX_TCP_KEEPIDLE 32767
160 #define MAX_TCP_KEEPINTVL 32767
161 #define MAX_TCP_KEEPCNT 127
162 #define MAX_TCP_SYNCNT 127
164 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
166 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
167 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
168 * after this time. It should be equal
169 * (or greater than) TCP_TIMEWAIT_LEN
170 * to provide reliability equal to one
171 * provided by timewait state.
173 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
174 * timestamps. It must be less than
175 * minimal timewait lifetime.
181 #define TCPOPT_NOP 1 /* Padding */
182 #define TCPOPT_EOL 0 /* End of options */
183 #define TCPOPT_MSS 2 /* Segment size negotiating */
184 #define TCPOPT_WINDOW 3 /* Window scaling */
185 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
186 #define TCPOPT_SACK 5 /* SACK Block */
187 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
188 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
189 #define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */
190 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
191 #define TCPOPT_EXP 254 /* Experimental */
192 /* Magic number to be after the option value for sharing TCP
193 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
195 #define TCPOPT_FASTOPEN_MAGIC 0xF989
196 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9
202 #define TCPOLEN_MSS 4
203 #define TCPOLEN_WINDOW 3
204 #define TCPOLEN_SACK_PERM 2
205 #define TCPOLEN_TIMESTAMP 10
206 #define TCPOLEN_MD5SIG 18
207 #define TCPOLEN_FASTOPEN_BASE 2
208 #define TCPOLEN_EXP_FASTOPEN_BASE 4
209 #define TCPOLEN_EXP_SMC_BASE 6
211 /* But this is what stacks really send out. */
212 #define TCPOLEN_TSTAMP_ALIGNED 12
213 #define TCPOLEN_WSCALE_ALIGNED 4
214 #define TCPOLEN_SACKPERM_ALIGNED 4
215 #define TCPOLEN_SACK_BASE 2
216 #define TCPOLEN_SACK_BASE_ALIGNED 4
217 #define TCPOLEN_SACK_PERBLOCK 8
218 #define TCPOLEN_MD5SIG_ALIGNED 20
219 #define TCPOLEN_MSS_ALIGNED 4
220 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
222 /* Flags in tp->nonagle */
223 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
224 #define TCP_NAGLE_CORK 2 /* Socket is corked */
225 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
227 /* TCP thin-stream limits */
228 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
230 /* TCP initial congestion window as per rfc6928 */
231 #define TCP_INIT_CWND 10
233 /* Bit Flags for sysctl_tcp_fastopen */
234 #define TFO_CLIENT_ENABLE 1
235 #define TFO_SERVER_ENABLE 2
236 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
238 /* Accept SYN data w/o any cookie option */
239 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
241 /* Force enable TFO on all listeners, i.e., not requiring the
242 * TCP_FASTOPEN socket option.
244 #define TFO_SERVER_WO_SOCKOPT1 0x400
247 /* sysctl variables for tcp */
248 extern int sysctl_tcp_max_orphans;
249 extern long sysctl_tcp_mem[3];
251 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
252 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
253 #define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
255 extern atomic_long_t tcp_memory_allocated;
256 DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
258 extern struct percpu_counter tcp_sockets_allocated;
259 extern unsigned long tcp_memory_pressure;
261 /* optimized version of sk_under_memory_pressure() for TCP sockets */
262 static inline bool tcp_under_memory_pressure(const struct sock *sk)
264 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
265 mem_cgroup_under_socket_pressure(sk->sk_memcg))
268 return READ_ONCE(tcp_memory_pressure);
271 * The next routines deal with comparing 32 bit unsigned ints
272 * and worry about wraparound (automatic with unsigned arithmetic).
275 static inline bool before(__u32 seq1, __u32 seq2)
277 return (__s32)(seq1-seq2) < 0;
279 #define after(seq2, seq1) before(seq1, seq2)
281 /* is s2<=s1<=s3 ? */
282 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
284 return seq3 - seq2 >= seq1 - seq2;
287 static inline bool tcp_out_of_memory(struct sock *sk)
289 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
290 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
295 static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
297 sk_wmem_queued_add(sk, -skb->truesize);
298 if (!skb_zcopy_pure(skb))
299 sk_mem_uncharge(sk, skb->truesize);
301 sk_mem_uncharge(sk, SKB_TRUESIZE(skb_end_offset(skb)));
305 void sk_forced_mem_schedule(struct sock *sk, int size);
307 bool tcp_check_oom(struct sock *sk, int shift);
310 extern struct proto tcp_prot;
312 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
313 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
314 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
315 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
317 void tcp_tasklet_init(void);
319 int tcp_v4_err(struct sk_buff *skb, u32);
321 void tcp_shutdown(struct sock *sk, int how);
323 int tcp_v4_early_demux(struct sk_buff *skb);
324 int tcp_v4_rcv(struct sk_buff *skb);
326 void tcp_remove_empty_skb(struct sock *sk);
327 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
328 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
329 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
330 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
332 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
333 size_t size, int flags);
334 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
335 size_t size, int flags);
336 int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
337 void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
339 void tcp_release_cb(struct sock *sk);
340 void tcp_wfree(struct sk_buff *skb);
341 void tcp_write_timer_handler(struct sock *sk);
342 void tcp_delack_timer_handler(struct sock *sk);
343 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
344 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
345 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
346 void tcp_rcv_space_adjust(struct sock *sk);
347 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
348 void tcp_twsk_destructor(struct sock *sk);
349 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
350 struct pipe_inode_info *pipe, size_t len,
352 struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
353 bool force_schedule);
355 void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
356 static inline void tcp_dec_quickack_mode(struct sock *sk,
357 const unsigned int pkts)
359 struct inet_connection_sock *icsk = inet_csk(sk);
361 if (icsk->icsk_ack.quick) {
362 if (pkts >= icsk->icsk_ack.quick) {
363 icsk->icsk_ack.quick = 0;
364 /* Leaving quickack mode we deflate ATO. */
365 icsk->icsk_ack.ato = TCP_ATO_MIN;
367 icsk->icsk_ack.quick -= pkts;
372 #define TCP_ECN_QUEUE_CWR 2
373 #define TCP_ECN_DEMAND_CWR 4
374 #define TCP_ECN_SEEN 8
384 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
386 const struct tcphdr *th);
387 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
388 struct request_sock *req, bool fastopen,
390 int tcp_child_process(struct sock *parent, struct sock *child,
391 struct sk_buff *skb);
392 void tcp_enter_loss(struct sock *sk);
393 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
394 void tcp_clear_retrans(struct tcp_sock *tp);
395 void tcp_update_metrics(struct sock *sk);
396 void tcp_init_metrics(struct sock *sk);
397 void tcp_metrics_init(void);
398 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
399 void __tcp_close(struct sock *sk, long timeout);
400 void tcp_close(struct sock *sk, long timeout);
401 void tcp_init_sock(struct sock *sk);
402 void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb);
403 __poll_t tcp_poll(struct file *file, struct socket *sock,
404 struct poll_table_struct *wait);
405 int tcp_getsockopt(struct sock *sk, int level, int optname,
406 char __user *optval, int __user *optlen);
407 bool tcp_bpf_bypass_getsockopt(int level, int optname);
408 int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
409 unsigned int optlen);
410 void tcp_set_keepalive(struct sock *sk, int val);
411 void tcp_syn_ack_timeout(const struct request_sock *req);
412 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
413 int flags, int *addr_len);
414 int tcp_set_rcvlowat(struct sock *sk, int val);
415 int tcp_set_window_clamp(struct sock *sk, int val);
416 void tcp_update_recv_tstamps(struct sk_buff *skb,
417 struct scm_timestamping_internal *tss);
418 void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
419 struct scm_timestamping_internal *tss);
420 void tcp_data_ready(struct sock *sk);
422 int tcp_mmap(struct file *file, struct socket *sock,
423 struct vm_area_struct *vma);
425 void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
426 struct tcp_options_received *opt_rx,
427 int estab, struct tcp_fastopen_cookie *foc);
428 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
431 * BPF SKB-less helpers
433 u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
434 struct tcphdr *th, u32 *cookie);
435 u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
436 struct tcphdr *th, u32 *cookie);
437 u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss);
438 u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
439 const struct tcp_request_sock_ops *af_ops,
440 struct sock *sk, struct tcphdr *th);
442 * TCP v4 functions exported for the inet6 API
445 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
446 void tcp_v4_mtu_reduced(struct sock *sk);
447 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
448 void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
449 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
450 struct sock *tcp_create_openreq_child(const struct sock *sk,
451 struct request_sock *req,
452 struct sk_buff *skb);
453 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
454 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
455 struct request_sock *req,
456 struct dst_entry *dst,
457 struct request_sock *req_unhash,
459 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
460 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
461 int tcp_connect(struct sock *sk);
462 enum tcp_synack_type {
467 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
468 struct request_sock *req,
469 struct tcp_fastopen_cookie *foc,
470 enum tcp_synack_type synack_type,
471 struct sk_buff *syn_skb);
472 int tcp_disconnect(struct sock *sk, int flags);
474 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
475 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
476 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
478 /* From syncookies.c */
479 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
480 struct request_sock *req,
481 struct dst_entry *dst, u32 tsoff);
482 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
484 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
485 struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
486 const struct tcp_request_sock_ops *af_ops,
487 struct sock *sk, struct sk_buff *skb);
488 #ifdef CONFIG_SYN_COOKIES
490 /* Syncookies use a monotonic timer which increments every 60 seconds.
491 * This counter is used both as a hash input and partially encoded into
492 * the cookie value. A cookie is only validated further if the delta
493 * between the current counter value and the encoded one is less than this,
494 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
495 * the counter advances immediately after a cookie is generated).
497 #define MAX_SYNCOOKIE_AGE 2
498 #define TCP_SYNCOOKIE_PERIOD (60 * HZ)
499 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
501 /* syncookies: remember time of last synqueue overflow
502 * But do not dirty this field too often (once per second is enough)
503 * It is racy as we do not hold a lock, but race is very minor.
505 static inline void tcp_synq_overflow(const struct sock *sk)
507 unsigned int last_overflow;
508 unsigned int now = jiffies;
510 if (sk->sk_reuseport) {
511 struct sock_reuseport *reuse;
513 reuse = rcu_dereference(sk->sk_reuseport_cb);
515 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
516 if (!time_between32(now, last_overflow,
518 WRITE_ONCE(reuse->synq_overflow_ts, now);
523 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
524 if (!time_between32(now, last_overflow, last_overflow + HZ))
525 WRITE_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp, now);
528 /* syncookies: no recent synqueue overflow on this listening socket? */
529 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
531 unsigned int last_overflow;
532 unsigned int now = jiffies;
534 if (sk->sk_reuseport) {
535 struct sock_reuseport *reuse;
537 reuse = rcu_dereference(sk->sk_reuseport_cb);
539 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
540 return !time_between32(now, last_overflow - HZ,
542 TCP_SYNCOOKIE_VALID);
546 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
548 /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
549 * then we're under synflood. However, we have to use
550 * 'last_overflow - HZ' as lower bound. That's because a concurrent
551 * tcp_synq_overflow() could update .ts_recent_stamp after we read
552 * jiffies but before we store .ts_recent_stamp into last_overflow,
553 * which could lead to rejecting a valid syncookie.
555 return !time_between32(now, last_overflow - HZ,
556 last_overflow + TCP_SYNCOOKIE_VALID);
559 static inline u32 tcp_cookie_time(void)
561 u64 val = get_jiffies_64();
563 do_div(val, TCP_SYNCOOKIE_PERIOD);
567 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
569 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
570 u64 cookie_init_timestamp(struct request_sock *req, u64 now);
571 bool cookie_timestamp_decode(const struct net *net,
572 struct tcp_options_received *opt);
573 bool cookie_ecn_ok(const struct tcp_options_received *opt,
574 const struct net *net, const struct dst_entry *dst);
576 /* From net/ipv6/syncookies.c */
577 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
579 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
581 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
582 const struct tcphdr *th, u16 *mssp);
583 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
587 void tcp_skb_entail(struct sock *sk, struct sk_buff *skb);
588 void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb);
589 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
591 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
592 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
593 void tcp_retransmit_timer(struct sock *sk);
594 void tcp_xmit_retransmit_queue(struct sock *);
595 void tcp_simple_retransmit(struct sock *);
596 void tcp_enter_recovery(struct sock *sk, bool ece_ack);
597 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
599 TCP_FRAG_IN_WRITE_QUEUE,
600 TCP_FRAG_IN_RTX_QUEUE,
602 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
603 struct sk_buff *skb, u32 len,
604 unsigned int mss_now, gfp_t gfp);
606 void tcp_send_probe0(struct sock *);
607 void tcp_send_partial(struct sock *);
608 int tcp_write_wakeup(struct sock *, int mib);
609 void tcp_send_fin(struct sock *sk);
610 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
611 int tcp_send_synack(struct sock *);
612 void tcp_push_one(struct sock *, unsigned int mss_now);
613 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
614 void tcp_send_ack(struct sock *sk);
615 void tcp_send_delayed_ack(struct sock *sk);
616 void tcp_send_loss_probe(struct sock *sk);
617 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
618 void tcp_skb_collapse_tstamp(struct sk_buff *skb,
619 const struct sk_buff *next_skb);
622 void tcp_rearm_rto(struct sock *sk);
623 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
624 void tcp_reset(struct sock *sk, struct sk_buff *skb);
625 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
626 void tcp_fin(struct sock *sk);
627 void tcp_check_space(struct sock *sk);
630 void tcp_init_xmit_timers(struct sock *);
631 static inline void tcp_clear_xmit_timers(struct sock *sk)
633 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
636 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
639 inet_csk_clear_xmit_timers(sk);
642 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
643 unsigned int tcp_current_mss(struct sock *sk);
644 u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when);
646 /* Bound MSS / TSO packet size with the half of the window */
647 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
651 /* When peer uses tiny windows, there is no use in packetizing
652 * to sub-MSS pieces for the sake of SWS or making sure there
653 * are enough packets in the pipe for fast recovery.
655 * On the other hand, for extremely large MSS devices, handling
656 * smaller than MSS windows in this way does make sense.
658 if (tp->max_window > TCP_MSS_DEFAULT)
659 cutoff = (tp->max_window >> 1);
661 cutoff = tp->max_window;
663 if (cutoff && pktsize > cutoff)
664 return max_t(int, cutoff, 68U - tp->tcp_header_len);
670 void tcp_get_info(struct sock *, struct tcp_info *);
672 /* Read 'sendfile()'-style from a TCP socket */
673 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
674 sk_read_actor_t recv_actor);
675 int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
676 struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off);
677 void tcp_read_done(struct sock *sk, size_t len);
679 void tcp_initialize_rcv_mss(struct sock *sk);
681 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
682 int tcp_mss_to_mtu(struct sock *sk, int mss);
683 void tcp_mtup_init(struct sock *sk);
685 static inline void tcp_bound_rto(const struct sock *sk)
687 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
688 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
691 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
693 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
696 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
698 /* mptcp hooks are only on the slow path */
699 if (sk_is_mptcp((struct sock *)tp))
702 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
703 ntohl(TCP_FLAG_ACK) |
707 static inline void tcp_fast_path_on(struct tcp_sock *tp)
709 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
712 static inline void tcp_fast_path_check(struct sock *sk)
714 struct tcp_sock *tp = tcp_sk(sk);
716 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
718 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
720 tcp_fast_path_on(tp);
723 /* Compute the actual rto_min value */
724 static inline u32 tcp_rto_min(struct sock *sk)
726 const struct dst_entry *dst = __sk_dst_get(sk);
727 u32 rto_min = inet_csk(sk)->icsk_rto_min;
729 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
730 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
734 static inline u32 tcp_rto_min_us(struct sock *sk)
736 return jiffies_to_usecs(tcp_rto_min(sk));
739 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
741 return dst_metric_locked(dst, RTAX_CC_ALGO);
744 /* Minimum RTT in usec. ~0 means not available. */
745 static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
747 return minmax_get(&tp->rtt_min);
750 /* Compute the actual receive window we are currently advertising.
751 * Rcv_nxt can be after the window if our peer push more data
752 * than the offered window.
754 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
756 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
763 /* Choose a new window, without checks for shrinking, and without
764 * scaling applied to the result. The caller does these things
765 * if necessary. This is a "raw" window selection.
767 u32 __tcp_select_window(struct sock *sk);
769 void tcp_send_window_probe(struct sock *sk);
771 /* TCP uses 32bit jiffies to save some space.
772 * Note that this is different from tcp_time_stamp, which
773 * historically has been the same until linux-4.13.
775 #define tcp_jiffies32 ((u32)jiffies)
778 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
779 * It is no longer tied to jiffies, but to 1 ms clock.
780 * Note: double check if you want to use tcp_jiffies32 instead of this.
782 #define TCP_TS_HZ 1000
784 static inline u64 tcp_clock_ns(void)
786 return ktime_get_ns();
789 static inline u64 tcp_clock_us(void)
791 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
794 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
795 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
797 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
800 /* Convert a nsec timestamp into TCP TSval timestamp (ms based currently) */
801 static inline u32 tcp_ns_to_ts(u64 ns)
803 return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ);
806 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
807 static inline u32 tcp_time_stamp_raw(void)
809 return tcp_ns_to_ts(tcp_clock_ns());
812 void tcp_mstamp_refresh(struct tcp_sock *tp);
814 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
816 return max_t(s64, t1 - t0, 0);
819 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
821 return tcp_ns_to_ts(skb->skb_mstamp_ns);
824 /* provide the departure time in us unit */
825 static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
827 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
831 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
833 #define TCPHDR_FIN 0x01
834 #define TCPHDR_SYN 0x02
835 #define TCPHDR_RST 0x04
836 #define TCPHDR_PSH 0x08
837 #define TCPHDR_ACK 0x10
838 #define TCPHDR_URG 0x20
839 #define TCPHDR_ECE 0x40
840 #define TCPHDR_CWR 0x80
842 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
844 /* This is what the send packet queuing engine uses to pass
845 * TCP per-packet control information to the transmission code.
846 * We also store the host-order sequence numbers in here too.
847 * This is 44 bytes if IPV6 is enabled.
848 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
851 __u32 seq; /* Starting sequence number */
852 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
854 /* Note : tcp_tw_isn is used in input path only
855 * (isn chosen by tcp_timewait_state_process())
857 * tcp_gso_segs/size are used in write queue only,
858 * cf tcp_skb_pcount()/tcp_skb_mss()
866 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
868 __u8 sacked; /* State flags for SACK. */
869 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
870 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
871 #define TCPCB_LOST 0x04 /* SKB is lost */
872 #define TCPCB_TAGBITS 0x07 /* All tag bits */
873 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */
874 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
875 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
878 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
879 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
880 eor:1, /* Is skb MSG_EOR marked? */
881 has_rxtstamp:1, /* SKB has a RX timestamp */
883 __u32 ack_seq; /* Sequence number ACK'd */
886 #define TCPCB_DELIVERED_CE_MASK ((1U<<20) - 1)
887 /* There is space for up to 24 bytes */
888 __u32 is_app_limited:1, /* cwnd not fully used? */
891 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
893 /* start of send pipeline phase */
895 /* when we reached the "delivered" count */
896 u64 delivered_mstamp;
897 } tx; /* only used for outgoing skbs */
899 struct inet_skb_parm h4;
900 #if IS_ENABLED(CONFIG_IPV6)
901 struct inet6_skb_parm h6;
903 } header; /* For incoming skbs */
907 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
909 extern const struct inet_connection_sock_af_ops ipv4_specific;
911 #if IS_ENABLED(CONFIG_IPV6)
912 /* This is the variant of inet6_iif() that must be used by TCP,
913 * as TCP moves IP6CB into a different location in skb->cb[]
915 static inline int tcp_v6_iif(const struct sk_buff *skb)
917 return TCP_SKB_CB(skb)->header.h6.iif;
920 static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
922 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
924 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
927 /* TCP_SKB_CB reference means this can not be used from early demux */
928 static inline int tcp_v6_sdif(const struct sk_buff *skb)
930 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
931 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
932 return TCP_SKB_CB(skb)->header.h6.iif;
937 extern const struct inet_connection_sock_af_ops ipv6_specific;
939 INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
940 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
941 void tcp_v6_early_demux(struct sk_buff *skb);
945 /* TCP_SKB_CB reference means this can not be used from early demux */
946 static inline int tcp_v4_sdif(struct sk_buff *skb)
948 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
949 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
950 return TCP_SKB_CB(skb)->header.h4.iif;
955 /* Due to TSO, an SKB can be composed of multiple actual
956 * packets. To keep these tracked properly, we use this.
958 static inline int tcp_skb_pcount(const struct sk_buff *skb)
960 return TCP_SKB_CB(skb)->tcp_gso_segs;
963 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
965 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
968 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
970 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
973 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
974 static inline int tcp_skb_mss(const struct sk_buff *skb)
976 return TCP_SKB_CB(skb)->tcp_gso_size;
979 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
981 return likely(!TCP_SKB_CB(skb)->eor);
984 static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
985 const struct sk_buff *from)
987 return likely(tcp_skb_can_collapse_to(to) &&
988 mptcp_skb_can_collapse(to, from) &&
989 skb_pure_zcopy_same(to, from));
992 /* Events passed to congestion control interface */
994 CA_EVENT_TX_START, /* first transmit when no packets in flight */
995 CA_EVENT_CWND_RESTART, /* congestion window restart */
996 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
997 CA_EVENT_LOSS, /* loss timeout */
998 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
999 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
1002 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1003 enum tcp_ca_ack_event_flags {
1004 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
1005 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
1006 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
1010 * Interface for adding new TCP congestion control handlers
1012 #define TCP_CA_NAME_MAX 16
1013 #define TCP_CA_MAX 128
1014 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
1016 #define TCP_CA_UNSPEC 0
1018 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1019 #define TCP_CONG_NON_RESTRICTED 0x1
1020 /* Requires ECN/ECT set on all packets */
1021 #define TCP_CONG_NEEDS_ECN 0x2
1022 #define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
1032 /* A rate sample measures the number of (original/retransmitted) data
1033 * packets delivered "delivered" over an interval of time "interval_us".
1034 * The tcp_rate.c code fills in the rate sample, and congestion
1035 * control modules that define a cong_control function to run at the end
1036 * of ACK processing can optionally chose to consult this sample when
1037 * setting cwnd and pacing rate.
1038 * A sample is invalid if "delivered" or "interval_us" is negative.
1040 struct rate_sample {
1041 u64 prior_mstamp; /* starting timestamp for interval */
1042 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1043 u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */
1044 s32 delivered; /* number of packets delivered over interval */
1045 s32 delivered_ce; /* number of packets delivered w/ CE marks*/
1046 long interval_us; /* time for tp->delivered to incr "delivered" */
1047 u32 snd_interval_us; /* snd interval for delivered packets */
1048 u32 rcv_interval_us; /* rcv interval for delivered packets */
1049 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1050 int losses; /* number of packets marked lost upon ACK */
1051 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1052 u32 prior_in_flight; /* in flight before this ACK */
1053 u32 last_end_seq; /* end_seq of most recently ACKed packet */
1054 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1055 bool is_retrans; /* is sample from retransmission? */
1056 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1059 struct tcp_congestion_ops {
1060 /* fast path fields are put first to fill one cache line */
1062 /* return slow start threshold (required) */
1063 u32 (*ssthresh)(struct sock *sk);
1065 /* do new cwnd calculation (required) */
1066 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1068 /* call before changing ca_state (optional) */
1069 void (*set_state)(struct sock *sk, u8 new_state);
1071 /* call when cwnd event occurs (optional) */
1072 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1074 /* call when ack arrives (optional) */
1075 void (*in_ack_event)(struct sock *sk, u32 flags);
1077 /* hook for packet ack accounting (optional) */
1078 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1080 /* override sysctl_tcp_min_tso_segs */
1081 u32 (*min_tso_segs)(struct sock *sk);
1083 /* call when packets are delivered to update cwnd and pacing rate,
1084 * after all the ca_state processing. (optional)
1086 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1089 /* new value of cwnd after loss (required) */
1090 u32 (*undo_cwnd)(struct sock *sk);
1091 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1092 u32 (*sndbuf_expand)(struct sock *sk);
1094 /* control/slow paths put last */
1095 /* get info for inet_diag (optional) */
1096 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1097 union tcp_cc_info *info);
1099 char name[TCP_CA_NAME_MAX];
1100 struct module *owner;
1101 struct list_head list;
1105 /* initialize private data (optional) */
1106 void (*init)(struct sock *sk);
1107 /* cleanup private data (optional) */
1108 void (*release)(struct sock *sk);
1109 } ____cacheline_aligned_in_smp;
1111 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1112 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1114 void tcp_assign_congestion_control(struct sock *sk);
1115 void tcp_init_congestion_control(struct sock *sk);
1116 void tcp_cleanup_congestion_control(struct sock *sk);
1117 int tcp_set_default_congestion_control(struct net *net, const char *name);
1118 void tcp_get_default_congestion_control(struct net *net, char *name);
1119 void tcp_get_available_congestion_control(char *buf, size_t len);
1120 void tcp_get_allowed_congestion_control(char *buf, size_t len);
1121 int tcp_set_allowed_congestion_control(char *allowed);
1122 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1123 bool cap_net_admin);
1124 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1125 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1127 u32 tcp_reno_ssthresh(struct sock *sk);
1128 u32 tcp_reno_undo_cwnd(struct sock *sk);
1129 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1130 extern struct tcp_congestion_ops tcp_reno;
1132 struct tcp_congestion_ops *tcp_ca_find(const char *name);
1133 struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1134 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1136 char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1138 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1144 static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1146 const struct inet_connection_sock *icsk = inet_csk(sk);
1148 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1151 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1153 const struct inet_connection_sock *icsk = inet_csk(sk);
1155 if (icsk->icsk_ca_ops->cwnd_event)
1156 icsk->icsk_ca_ops->cwnd_event(sk, event);
1159 /* From tcp_cong.c */
1160 void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
1162 /* From tcp_rate.c */
1163 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1164 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1165 struct rate_sample *rs);
1166 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1167 bool is_sack_reneg, struct rate_sample *rs);
1168 void tcp_rate_check_app_limited(struct sock *sk);
1170 static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
1172 return t1 > t2 || (t1 == t2 && after(seq1, seq2));
1175 /* These functions determine how the current flow behaves in respect of SACK
1176 * handling. SACK is negotiated with the peer, and therefore it can vary
1177 * between different flows.
1179 * tcp_is_sack - SACK enabled
1180 * tcp_is_reno - No SACK
1182 static inline int tcp_is_sack(const struct tcp_sock *tp)
1184 return likely(tp->rx_opt.sack_ok);
1187 static inline bool tcp_is_reno(const struct tcp_sock *tp)
1189 return !tcp_is_sack(tp);
1192 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1194 return tp->sacked_out + tp->lost_out;
1197 /* This determines how many packets are "in the network" to the best
1198 * of our knowledge. In many cases it is conservative, but where
1199 * detailed information is available from the receiver (via SACK
1200 * blocks etc.) we can make more aggressive calculations.
1202 * Use this for decisions involving congestion control, use just
1203 * tp->packets_out to determine if the send queue is empty or not.
1205 * Read this equation as:
1207 * "Packets sent once on transmission queue" MINUS
1208 * "Packets left network, but not honestly ACKed yet" PLUS
1209 * "Packets fast retransmitted"
1211 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1213 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1216 #define TCP_INFINITE_SSTHRESH 0x7fffffff
1218 static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
1220 return tp->snd_cwnd;
1223 static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
1225 WARN_ON_ONCE((int)val <= 0);
1229 static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1231 return tcp_snd_cwnd(tp) < tp->snd_ssthresh;
1234 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1236 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1239 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1241 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1242 (1 << inet_csk(sk)->icsk_ca_state);
1245 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1246 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1249 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1251 const struct tcp_sock *tp = tcp_sk(sk);
1253 if (tcp_in_cwnd_reduction(sk))
1254 return tp->snd_ssthresh;
1256 return max(tp->snd_ssthresh,
1257 ((tcp_snd_cwnd(tp) >> 1) +
1258 (tcp_snd_cwnd(tp) >> 2)));
1261 /* Use define here intentionally to get WARN_ON location shown at the caller */
1262 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1264 void tcp_enter_cwr(struct sock *sk);
1265 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1267 /* The maximum number of MSS of available cwnd for which TSO defers
1268 * sending if not using sysctl_tcp_tso_win_divisor.
1270 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1275 /* Returns end sequence number of the receiver's advertised window */
1276 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1278 return tp->snd_una + tp->snd_wnd;
1281 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1282 * flexible approach. The RFC suggests cwnd should not be raised unless
1283 * it was fully used previously. And that's exactly what we do in
1284 * congestion avoidance mode. But in slow start we allow cwnd to grow
1285 * as long as the application has used half the cwnd.
1287 * cwnd is 10 (IW10), but application sends 9 frames.
1288 * We allow cwnd to reach 18 when all frames are ACKed.
1289 * This check is safe because it's as aggressive as slow start which already
1290 * risks 100% overshoot. The advantage is that we discourage application to
1291 * either send more filler packets or data to artificially blow up the cwnd
1292 * usage, and allow application-limited process to probe bw more aggressively.
1294 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1296 const struct tcp_sock *tp = tcp_sk(sk);
1298 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1299 if (tcp_in_slow_start(tp))
1300 return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out;
1302 return tp->is_cwnd_limited;
1305 /* BBR congestion control needs pacing.
1306 * Same remark for SO_MAX_PACING_RATE.
1307 * sch_fq packet scheduler is efficiently handling pacing,
1308 * but is not always installed/used.
1309 * Return true if TCP stack should pace packets itself.
1311 static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1313 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1316 /* Estimates in how many jiffies next packet for this flow can be sent.
1317 * Scheduling a retransmit timer too early would be silly.
1319 static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1321 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1323 return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1326 static inline void tcp_reset_xmit_timer(struct sock *sk,
1329 const unsigned long max_when)
1331 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1335 /* Something is really bad, we could not queue an additional packet,
1336 * because qdisc is full or receiver sent a 0 window, or we are paced.
1337 * We do not want to add fuel to the fire, or abort too early,
1338 * so make sure the timer we arm now is at least 200ms in the future,
1339 * regardless of current icsk_rto value (as it could be ~2ms)
1341 static inline unsigned long tcp_probe0_base(const struct sock *sk)
1343 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1346 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1347 static inline unsigned long tcp_probe0_when(const struct sock *sk,
1348 unsigned long max_when)
1350 u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1,
1351 inet_csk(sk)->icsk_backoff);
1352 u64 when = (u64)tcp_probe0_base(sk) << backoff;
1354 return (unsigned long)min_t(u64, when, max_when);
1357 static inline void tcp_check_probe_timer(struct sock *sk)
1359 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1360 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1361 tcp_probe0_base(sk), TCP_RTO_MAX);
1364 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1369 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1375 * Calculate(/check) TCP checksum
1377 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1378 __be32 daddr, __wsum base)
1380 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1383 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1385 return !skb_csum_unnecessary(skb) &&
1386 __skb_checksum_complete(skb);
1389 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
1390 enum skb_drop_reason *reason);
1393 int tcp_filter(struct sock *sk, struct sk_buff *skb);
1394 void tcp_set_state(struct sock *sk, int state);
1395 void tcp_done(struct sock *sk);
1396 int tcp_abort(struct sock *sk, int err);
1398 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1401 rx_opt->num_sacks = 0;
1404 void tcp_cwnd_restart(struct sock *sk, s32 delta);
1406 static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1408 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1409 struct tcp_sock *tp = tcp_sk(sk);
1412 if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) ||
1413 tp->packets_out || ca_ops->cong_control)
1415 delta = tcp_jiffies32 - tp->lsndtime;
1416 if (delta > inet_csk(sk)->icsk_rto)
1417 tcp_cwnd_restart(sk, delta);
1420 /* Determine a window scaling and initial window to offer. */
1421 void tcp_select_initial_window(const struct sock *sk, int __space,
1422 __u32 mss, __u32 *rcv_wnd,
1423 __u32 *window_clamp, int wscale_ok,
1424 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1426 static inline int tcp_win_from_space(const struct sock *sk, int space)
1428 int tcp_adv_win_scale = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale);
1430 return tcp_adv_win_scale <= 0 ?
1431 (space>>(-tcp_adv_win_scale)) :
1432 space - (space>>tcp_adv_win_scale);
1435 /* Note: caller must be prepared to deal with negative returns */
1436 static inline int tcp_space(const struct sock *sk)
1438 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1439 READ_ONCE(sk->sk_backlog.len) -
1440 atomic_read(&sk->sk_rmem_alloc));
1443 static inline int tcp_full_space(const struct sock *sk)
1445 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1448 static inline void tcp_adjust_rcv_ssthresh(struct sock *sk)
1450 int unused_mem = sk_unused_reserved_mem(sk);
1451 struct tcp_sock *tp = tcp_sk(sk);
1453 tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
1455 tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh,
1456 tcp_win_from_space(sk, unused_mem));
1459 void tcp_cleanup_rbuf(struct sock *sk, int copied);
1461 /* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1462 * If 87.5 % (7/8) of the space has been consumed, we want to override
1463 * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1464 * len/truesize ratio.
1466 static inline bool tcp_rmem_pressure(const struct sock *sk)
1468 int rcvbuf, threshold;
1470 if (tcp_under_memory_pressure(sk))
1473 rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1474 threshold = rcvbuf - (rcvbuf >> 3);
1476 return atomic_read(&sk->sk_rmem_alloc) > threshold;
1479 static inline bool tcp_epollin_ready(const struct sock *sk, int target)
1481 const struct tcp_sock *tp = tcp_sk(sk);
1482 int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);
1487 return (avail >= target) || tcp_rmem_pressure(sk) ||
1488 (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss);
1491 extern void tcp_openreq_init_rwin(struct request_sock *req,
1492 const struct sock *sk_listener,
1493 const struct dst_entry *dst);
1495 void tcp_enter_memory_pressure(struct sock *sk);
1496 void tcp_leave_memory_pressure(struct sock *sk);
1498 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1500 struct net *net = sock_net((struct sock *)tp);
1502 return tp->keepalive_intvl ? :
1503 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
1506 static inline int keepalive_time_when(const struct tcp_sock *tp)
1508 struct net *net = sock_net((struct sock *)tp);
1510 return tp->keepalive_time ? :
1511 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
1514 static inline int keepalive_probes(const struct tcp_sock *tp)
1516 struct net *net = sock_net((struct sock *)tp);
1518 return tp->keepalive_probes ? :
1519 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes);
1522 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1524 const struct inet_connection_sock *icsk = &tp->inet_conn;
1526 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1527 tcp_jiffies32 - tp->rcv_tstamp);
1530 static inline int tcp_fin_time(const struct sock *sk)
1532 int fin_timeout = tcp_sk(sk)->linger2 ? :
1533 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout);
1534 const int rto = inet_csk(sk)->icsk_rto;
1536 if (fin_timeout < (rto << 2) - (rto >> 1))
1537 fin_timeout = (rto << 2) - (rto >> 1);
1542 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1545 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1547 if (unlikely(!time_before32(ktime_get_seconds(),
1548 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1551 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1552 * then following tcp messages have valid values. Ignore 0 value,
1553 * or else 'negative' tsval might forbid us to accept their packets.
1555 if (!rx_opt->ts_recent)
1560 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1563 if (tcp_paws_check(rx_opt, 0))
1566 /* RST segments are not recommended to carry timestamp,
1567 and, if they do, it is recommended to ignore PAWS because
1568 "their cleanup function should take precedence over timestamps."
1569 Certainly, it is mistake. It is necessary to understand the reasons
1570 of this constraint to relax it: if peer reboots, clock may go
1571 out-of-sync and half-open connections will not be reset.
1572 Actually, the problem would be not existing if all
1573 the implementations followed draft about maintaining clock
1574 via reboots. Linux-2.2 DOES NOT!
1576 However, we can relax time bounds for RST segments to MSL.
1578 if (rst && !time_before32(ktime_get_seconds(),
1579 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1584 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1585 int mib_idx, u32 *last_oow_ack_time);
1587 static inline void tcp_mib_init(struct net *net)
1590 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1591 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1592 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1593 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1597 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1599 tp->lost_skb_hint = NULL;
1602 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1604 tcp_clear_retrans_hints_partial(tp);
1605 tp->retransmit_skb_hint = NULL;
1608 union tcp_md5_addr {
1610 #if IS_ENABLED(CONFIG_IPV6)
1615 /* - key database */
1616 struct tcp_md5sig_key {
1617 struct hlist_node node;
1619 u8 family; /* AF_INET or AF_INET6 */
1622 union tcp_md5_addr addr;
1623 int l3index; /* set if key added with L3 scope */
1624 u8 key[TCP_MD5SIG_MAXKEYLEN];
1625 struct rcu_head rcu;
1629 struct tcp_md5sig_info {
1630 struct hlist_head head;
1631 struct rcu_head rcu;
1634 /* - pseudo header */
1635 struct tcp4_pseudohdr {
1643 struct tcp6_pseudohdr {
1644 struct in6_addr saddr;
1645 struct in6_addr daddr;
1647 __be32 protocol; /* including padding */
1650 union tcp_md5sum_block {
1651 struct tcp4_pseudohdr ip4;
1652 #if IS_ENABLED(CONFIG_IPV6)
1653 struct tcp6_pseudohdr ip6;
1657 /* - pool: digest algorithm, hash description and scratch buffer */
1658 struct tcp_md5sig_pool {
1659 struct ahash_request *md5_req;
1664 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1665 const struct sock *sk, const struct sk_buff *skb);
1666 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1667 int family, u8 prefixlen, int l3index, u8 flags,
1668 const u8 *newkey, u8 newkeylen, gfp_t gfp);
1669 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1670 int family, u8 prefixlen, int l3index, u8 flags);
1671 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1672 const struct sock *addr_sk);
1674 #ifdef CONFIG_TCP_MD5SIG
1675 #include <linux/jump_label.h>
1676 extern struct static_key_false tcp_md5_needed;
1677 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1678 const union tcp_md5_addr *addr,
1680 static inline struct tcp_md5sig_key *
1681 tcp_md5_do_lookup(const struct sock *sk, int l3index,
1682 const union tcp_md5_addr *addr, int family)
1684 if (!static_branch_unlikely(&tcp_md5_needed))
1686 return __tcp_md5_do_lookup(sk, l3index, addr, family);
1689 enum skb_drop_reason
1690 tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1691 const void *saddr, const void *daddr,
1692 int family, int dif, int sdif);
1695 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1697 static inline struct tcp_md5sig_key *
1698 tcp_md5_do_lookup(const struct sock *sk, int l3index,
1699 const union tcp_md5_addr *addr, int family)
1704 static inline enum skb_drop_reason
1705 tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1706 const void *saddr, const void *daddr,
1707 int family, int dif, int sdif)
1709 return SKB_NOT_DROPPED_YET;
1711 #define tcp_twsk_md5_key(twsk) NULL
1714 bool tcp_alloc_md5sig_pool(void);
1716 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1717 static inline void tcp_put_md5sig_pool(void)
1722 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1723 unsigned int header_len);
1724 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1725 const struct tcp_md5sig_key *key);
1727 /* From tcp_fastopen.c */
1728 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1729 struct tcp_fastopen_cookie *cookie);
1730 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1731 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1733 struct tcp_fastopen_request {
1734 /* Fast Open cookie. Size 0 means a cookie request */
1735 struct tcp_fastopen_cookie cookie;
1736 struct msghdr *data; /* data in MSG_FASTOPEN */
1738 int copied; /* queued in tcp_connect() */
1739 struct ubuf_info *uarg;
1741 void tcp_free_fastopen_req(struct tcp_sock *tp);
1742 void tcp_fastopen_destroy_cipher(struct sock *sk);
1743 void tcp_fastopen_ctx_destroy(struct net *net);
1744 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1745 void *primary_key, void *backup_key);
1746 int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1748 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1749 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1750 struct request_sock *req,
1751 struct tcp_fastopen_cookie *foc,
1752 const struct dst_entry *dst);
1753 void tcp_fastopen_init_key_once(struct net *net);
1754 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1755 struct tcp_fastopen_cookie *cookie);
1756 bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1757 #define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1758 #define TCP_FASTOPEN_KEY_MAX 2
1759 #define TCP_FASTOPEN_KEY_BUF_LENGTH \
1760 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1762 /* Fastopen key context */
1763 struct tcp_fastopen_context {
1764 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1766 struct rcu_head rcu;
1769 void tcp_fastopen_active_disable(struct sock *sk);
1770 bool tcp_fastopen_active_should_disable(struct sock *sk);
1771 void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1772 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1774 /* Caller needs to wrap with rcu_read_(un)lock() */
1776 struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1778 struct tcp_fastopen_context *ctx;
1780 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1782 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1787 bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1788 const struct tcp_fastopen_cookie *orig)
1790 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1791 orig->len == foc->len &&
1792 !memcmp(orig->val, foc->val, foc->len))
1798 int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1803 /* Latencies incurred by various limits for a sender. They are
1804 * chronograph-like stats that are mutually exclusive.
1808 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1809 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1810 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1814 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1815 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1817 /* This helper is needed, because skb->tcp_tsorted_anchor uses
1818 * the same memory storage than skb->destructor/_skb_refdst
1820 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1822 skb->destructor = NULL;
1823 skb->_skb_refdst = 0UL;
1826 #define tcp_skb_tsorted_save(skb) { \
1827 unsigned long _save = skb->_skb_refdst; \
1828 skb->_skb_refdst = 0UL;
1830 #define tcp_skb_tsorted_restore(skb) \
1831 skb->_skb_refdst = _save; \
1834 void tcp_write_queue_purge(struct sock *sk);
1836 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1838 return skb_rb_first(&sk->tcp_rtx_queue);
1841 static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1843 return skb_rb_last(&sk->tcp_rtx_queue);
1846 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1848 return skb_peek_tail(&sk->sk_write_queue);
1851 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1852 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1854 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1856 return skb_peek(&sk->sk_write_queue);
1859 static inline bool tcp_skb_is_last(const struct sock *sk,
1860 const struct sk_buff *skb)
1862 return skb_queue_is_last(&sk->sk_write_queue, skb);
1866 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
1869 * Since the write queue can have a temporary empty skb in it,
1870 * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
1872 static inline bool tcp_write_queue_empty(const struct sock *sk)
1874 const struct tcp_sock *tp = tcp_sk(sk);
1876 return tp->write_seq == tp->snd_nxt;
1879 static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1881 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1884 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1886 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1889 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1891 __skb_queue_tail(&sk->sk_write_queue, skb);
1893 /* Queue it, remembering where we must start sending. */
1894 if (sk->sk_write_queue.next == skb)
1895 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1898 /* Insert new before skb on the write queue of sk. */
1899 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1900 struct sk_buff *skb,
1903 __skb_queue_before(&sk->sk_write_queue, skb, new);
1906 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1908 tcp_skb_tsorted_anchor_cleanup(skb);
1909 __skb_unlink(skb, &sk->sk_write_queue);
1912 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1914 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1916 tcp_skb_tsorted_anchor_cleanup(skb);
1917 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1920 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1922 list_del(&skb->tcp_tsorted_anchor);
1923 tcp_rtx_queue_unlink(skb, sk);
1924 tcp_wmem_free_skb(sk, skb);
1927 static inline void tcp_push_pending_frames(struct sock *sk)
1929 if (tcp_send_head(sk)) {
1930 struct tcp_sock *tp = tcp_sk(sk);
1932 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1936 /* Start sequence of the skb just after the highest skb with SACKed
1937 * bit, valid only if sacked_out > 0 or when the caller has ensured
1938 * validity by itself.
1940 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1942 if (!tp->sacked_out)
1945 if (tp->highest_sack == NULL)
1948 return TCP_SKB_CB(tp->highest_sack)->seq;
1951 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1953 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1956 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1958 return tcp_sk(sk)->highest_sack;
1961 static inline void tcp_highest_sack_reset(struct sock *sk)
1963 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1966 /* Called when old skb is about to be deleted and replaced by new skb */
1967 static inline void tcp_highest_sack_replace(struct sock *sk,
1968 struct sk_buff *old,
1969 struct sk_buff *new)
1971 if (old == tcp_highest_sack(sk))
1972 tcp_sk(sk)->highest_sack = new;
1975 /* This helper checks if socket has IP_TRANSPARENT set */
1976 static inline bool inet_sk_transparent(const struct sock *sk)
1978 switch (sk->sk_state) {
1980 return inet_twsk(sk)->tw_transparent;
1981 case TCP_NEW_SYN_RECV:
1982 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1984 return inet_sk(sk)->transparent;
1987 /* Determines whether this is a thin stream (which may suffer from
1988 * increased latency). Used to trigger latency-reducing mechanisms.
1990 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1992 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1996 enum tcp_seq_states {
1997 TCP_SEQ_STATE_LISTENING,
1998 TCP_SEQ_STATE_ESTABLISHED,
2001 void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
2002 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
2003 void tcp_seq_stop(struct seq_file *seq, void *v);
2005 struct tcp_seq_afinfo {
2009 struct tcp_iter_state {
2010 struct seq_net_private p;
2011 enum tcp_seq_states state;
2012 struct sock *syn_wait_sk;
2013 int bucket, offset, sbucket, num;
2017 extern struct request_sock_ops tcp_request_sock_ops;
2018 extern struct request_sock_ops tcp6_request_sock_ops;
2020 void tcp_v4_destroy_sock(struct sock *sk);
2022 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
2023 netdev_features_t features);
2024 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
2025 INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
2026 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
2027 INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
2028 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
2029 int tcp_gro_complete(struct sk_buff *skb);
2031 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
2033 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
2035 struct net *net = sock_net((struct sock *)tp);
2036 return tp->notsent_lowat ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);
2039 bool tcp_stream_memory_free(const struct sock *sk, int wake);
2041 #ifdef CONFIG_PROC_FS
2042 int tcp4_proc_init(void);
2043 void tcp4_proc_exit(void);
2046 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
2047 int tcp_conn_request(struct request_sock_ops *rsk_ops,
2048 const struct tcp_request_sock_ops *af_ops,
2049 struct sock *sk, struct sk_buff *skb);
2051 /* TCP af-specific functions */
2052 struct tcp_sock_af_ops {
2053 #ifdef CONFIG_TCP_MD5SIG
2054 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
2055 const struct sock *addr_sk);
2056 int (*calc_md5_hash)(char *location,
2057 const struct tcp_md5sig_key *md5,
2058 const struct sock *sk,
2059 const struct sk_buff *skb);
2060 int (*md5_parse)(struct sock *sk,
2067 struct tcp_request_sock_ops {
2069 #ifdef CONFIG_TCP_MD5SIG
2070 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2071 const struct sock *addr_sk);
2072 int (*calc_md5_hash) (char *location,
2073 const struct tcp_md5sig_key *md5,
2074 const struct sock *sk,
2075 const struct sk_buff *skb);
2077 #ifdef CONFIG_SYN_COOKIES
2078 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
2081 struct dst_entry *(*route_req)(const struct sock *sk,
2082 struct sk_buff *skb,
2084 struct request_sock *req);
2085 u32 (*init_seq)(const struct sk_buff *skb);
2086 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2087 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2088 struct flowi *fl, struct request_sock *req,
2089 struct tcp_fastopen_cookie *foc,
2090 enum tcp_synack_type synack_type,
2091 struct sk_buff *syn_skb);
2094 extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2095 #if IS_ENABLED(CONFIG_IPV6)
2096 extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2099 #ifdef CONFIG_SYN_COOKIES
2100 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2101 const struct sock *sk, struct sk_buff *skb,
2104 tcp_synq_overflow(sk);
2105 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2106 return ops->cookie_init_seq(skb, mss);
2109 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2110 const struct sock *sk, struct sk_buff *skb,
2117 int tcpv4_offload_init(void);
2119 void tcp_v4_init(void);
2120 void tcp_init(void);
2122 /* tcp_recovery.c */
2123 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2124 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2125 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2127 extern bool tcp_rack_mark_lost(struct sock *sk);
2128 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2130 extern void tcp_rack_reo_timeout(struct sock *sk);
2131 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2133 /* At how many usecs into the future should the RTO fire? */
2134 static inline s64 tcp_rto_delta_us(const struct sock *sk)
2136 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2137 u32 rto = inet_csk(sk)->icsk_rto;
2138 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2140 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2144 * Save and compile IPv4 options, return a pointer to it
2146 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2147 struct sk_buff *skb)
2149 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2150 struct ip_options_rcu *dopt = NULL;
2153 int opt_size = sizeof(*dopt) + opt->optlen;
2155 dopt = kmalloc(opt_size, GFP_ATOMIC);
2156 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2164 /* locally generated TCP pure ACKs have skb->truesize == 2
2165 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2166 * This is much faster than dissecting the packet to find out.
2167 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2169 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2171 return skb->truesize == 2;
2174 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2179 static inline int tcp_inq(struct sock *sk)
2181 struct tcp_sock *tp = tcp_sk(sk);
2184 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2186 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2188 before(tp->urg_seq, tp->copied_seq) ||
2189 !before(tp->urg_seq, tp->rcv_nxt)) {
2191 answ = tp->rcv_nxt - tp->copied_seq;
2193 /* Subtract 1, if FIN was received */
2194 if (answ && sock_flag(sk, SOCK_DONE))
2197 answ = tp->urg_seq - tp->copied_seq;
2203 int tcp_peek_len(struct socket *sock);
2205 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2209 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2211 /* We update these fields while other threads might
2212 * read them from tcp_get_info()
2214 WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in);
2215 if (skb->len > tcp_hdrlen(skb))
2216 WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in);
2220 * TCP listen path runs lockless.
2221 * We forced "struct sock" to be const qualified to make sure
2222 * we don't modify one of its field by mistake.
2223 * Here, we increment sk_drops which is an atomic_t, so we can safely
2224 * make sock writable again.
2226 static inline void tcp_listendrop(const struct sock *sk)
2228 atomic_inc(&((struct sock *)sk)->sk_drops);
2229 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2232 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2235 * Interface for adding Upper Level Protocols over TCP
2238 #define TCP_ULP_NAME_MAX 16
2239 #define TCP_ULP_MAX 128
2240 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2242 struct tcp_ulp_ops {
2243 struct list_head list;
2245 /* initialize ulp */
2246 int (*init)(struct sock *sk);
2248 void (*update)(struct sock *sk, struct proto *p,
2249 void (*write_space)(struct sock *sk));
2251 void (*release)(struct sock *sk);
2253 int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2254 size_t (*get_info_size)(const struct sock *sk);
2256 void (*clone)(const struct request_sock *req, struct sock *newsk,
2257 const gfp_t priority);
2259 char name[TCP_ULP_NAME_MAX];
2260 struct module *owner;
2262 int tcp_register_ulp(struct tcp_ulp_ops *type);
2263 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2264 int tcp_set_ulp(struct sock *sk, const char *name);
2265 void tcp_get_available_ulp(char *buf, size_t len);
2266 void tcp_cleanup_ulp(struct sock *sk);
2267 void tcp_update_ulp(struct sock *sk, struct proto *p,
2268 void (*write_space)(struct sock *sk));
2270 #define MODULE_ALIAS_TCP_ULP(name) \
2271 __MODULE_INFO(alias, alias_userspace, name); \
2272 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2274 #ifdef CONFIG_NET_SOCK_MSG
2278 #ifdef CONFIG_BPF_SYSCALL
2279 struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
2280 int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
2281 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2282 #endif /* CONFIG_BPF_SYSCALL */
2284 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
2286 #endif /* CONFIG_NET_SOCK_MSG */
2288 #if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)
2289 static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2294 #ifdef CONFIG_CGROUP_BPF
2295 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2296 struct sk_buff *skb,
2297 unsigned int end_offset)
2300 skops->skb_data_end = skb->data + end_offset;
2303 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2304 struct sk_buff *skb,
2305 unsigned int end_offset)
2310 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2311 * is < 0, then the BPF op failed (for example if the loaded BPF
2312 * program does not support the chosen operation or there is no BPF
2316 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2318 struct bpf_sock_ops_kern sock_ops;
2321 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2322 if (sk_fullsock(sk)) {
2323 sock_ops.is_fullsock = 1;
2324 sock_owned_by_me(sk);
2330 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2332 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2334 ret = sock_ops.reply;
2340 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2342 u32 args[2] = {arg1, arg2};
2344 return tcp_call_bpf(sk, op, 2, args);
2347 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2350 u32 args[3] = {arg1, arg2, arg3};
2352 return tcp_call_bpf(sk, op, 3, args);
2356 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2361 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2366 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2374 static inline u32 tcp_timeout_init(struct sock *sk)
2378 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2381 timeout = TCP_TIMEOUT_INIT;
2382 return min_t(int, timeout, TCP_RTO_MAX);
2385 static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2389 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2396 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2398 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2401 static inline void tcp_bpf_rtt(struct sock *sk)
2403 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2404 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2407 #if IS_ENABLED(CONFIG_SMC)
2408 extern struct static_key_false tcp_have_smc;
2411 #if IS_ENABLED(CONFIG_TLS_DEVICE)
2412 void clean_acked_data_enable(struct inet_connection_sock *icsk,
2413 void (*cad)(struct sock *sk, u32 ack_seq));
2414 void clean_acked_data_disable(struct inet_connection_sock *icsk);
2415 void clean_acked_data_flush(void);
2418 DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2419 static inline void tcp_add_tx_delay(struct sk_buff *skb,
2420 const struct tcp_sock *tp)
2422 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2423 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2426 /* Compute Earliest Departure Time for some control packets
2427 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2429 static inline u64 tcp_transmit_time(const struct sock *sk)
2431 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2432 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2433 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2435 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;