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_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
331 size_t size, struct ubuf_info *uarg);
332 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
334 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
335 size_t size, int flags);
336 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
337 size_t size, int flags);
338 int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
339 void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
341 void tcp_release_cb(struct sock *sk);
342 void tcp_wfree(struct sk_buff *skb);
343 void tcp_write_timer_handler(struct sock *sk);
344 void tcp_delack_timer_handler(struct sock *sk);
345 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
346 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
347 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
348 void tcp_rcv_space_adjust(struct sock *sk);
349 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
350 void tcp_twsk_destructor(struct sock *sk);
351 void tcp_twsk_purge(struct list_head *net_exit_list, int family);
352 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
353 struct pipe_inode_info *pipe, size_t len,
355 struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
356 bool force_schedule);
358 void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
359 static inline void tcp_dec_quickack_mode(struct sock *sk,
360 const unsigned int pkts)
362 struct inet_connection_sock *icsk = inet_csk(sk);
364 if (icsk->icsk_ack.quick) {
365 if (pkts >= icsk->icsk_ack.quick) {
366 icsk->icsk_ack.quick = 0;
367 /* Leaving quickack mode we deflate ATO. */
368 icsk->icsk_ack.ato = TCP_ATO_MIN;
370 icsk->icsk_ack.quick -= pkts;
375 #define TCP_ECN_QUEUE_CWR 2
376 #define TCP_ECN_DEMAND_CWR 4
377 #define TCP_ECN_SEEN 8
387 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
389 const struct tcphdr *th);
390 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
391 struct request_sock *req, bool fastopen,
393 int tcp_child_process(struct sock *parent, struct sock *child,
394 struct sk_buff *skb);
395 void tcp_enter_loss(struct sock *sk);
396 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
397 void tcp_clear_retrans(struct tcp_sock *tp);
398 void tcp_update_metrics(struct sock *sk);
399 void tcp_init_metrics(struct sock *sk);
400 void tcp_metrics_init(void);
401 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
402 void __tcp_close(struct sock *sk, long timeout);
403 void tcp_close(struct sock *sk, long timeout);
404 void tcp_init_sock(struct sock *sk);
405 void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb);
406 __poll_t tcp_poll(struct file *file, struct socket *sock,
407 struct poll_table_struct *wait);
408 int do_tcp_getsockopt(struct sock *sk, int level,
409 int optname, sockptr_t optval, sockptr_t optlen);
410 int tcp_getsockopt(struct sock *sk, int level, int optname,
411 char __user *optval, int __user *optlen);
412 bool tcp_bpf_bypass_getsockopt(int level, int optname);
413 int do_tcp_setsockopt(struct sock *sk, int level, int optname,
414 sockptr_t optval, unsigned int optlen);
415 int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
416 unsigned int optlen);
417 void tcp_set_keepalive(struct sock *sk, int val);
418 void tcp_syn_ack_timeout(const struct request_sock *req);
419 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
420 int flags, int *addr_len);
421 int tcp_set_rcvlowat(struct sock *sk, int val);
422 int tcp_set_window_clamp(struct sock *sk, int val);
423 void tcp_update_recv_tstamps(struct sk_buff *skb,
424 struct scm_timestamping_internal *tss);
425 void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
426 struct scm_timestamping_internal *tss);
427 void tcp_data_ready(struct sock *sk);
429 int tcp_mmap(struct file *file, struct socket *sock,
430 struct vm_area_struct *vma);
432 void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
433 struct tcp_options_received *opt_rx,
434 int estab, struct tcp_fastopen_cookie *foc);
435 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
438 * BPF SKB-less helpers
440 u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
441 struct tcphdr *th, u32 *cookie);
442 u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
443 struct tcphdr *th, u32 *cookie);
444 u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss);
445 u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
446 const struct tcp_request_sock_ops *af_ops,
447 struct sock *sk, struct tcphdr *th);
449 * TCP v4 functions exported for the inet6 API
452 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
453 void tcp_v4_mtu_reduced(struct sock *sk);
454 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
455 void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
456 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
457 struct sock *tcp_create_openreq_child(const struct sock *sk,
458 struct request_sock *req,
459 struct sk_buff *skb);
460 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
461 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
462 struct request_sock *req,
463 struct dst_entry *dst,
464 struct request_sock *req_unhash,
466 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
467 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
468 int tcp_connect(struct sock *sk);
469 enum tcp_synack_type {
474 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
475 struct request_sock *req,
476 struct tcp_fastopen_cookie *foc,
477 enum tcp_synack_type synack_type,
478 struct sk_buff *syn_skb);
479 int tcp_disconnect(struct sock *sk, int flags);
481 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
482 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
483 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
485 /* From syncookies.c */
486 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
487 struct request_sock *req,
488 struct dst_entry *dst, u32 tsoff);
489 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
491 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
492 struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
493 const struct tcp_request_sock_ops *af_ops,
494 struct sock *sk, struct sk_buff *skb);
495 #ifdef CONFIG_SYN_COOKIES
497 /* Syncookies use a monotonic timer which increments every 60 seconds.
498 * This counter is used both as a hash input and partially encoded into
499 * the cookie value. A cookie is only validated further if the delta
500 * between the current counter value and the encoded one is less than this,
501 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
502 * the counter advances immediately after a cookie is generated).
504 #define MAX_SYNCOOKIE_AGE 2
505 #define TCP_SYNCOOKIE_PERIOD (60 * HZ)
506 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
508 /* syncookies: remember time of last synqueue overflow
509 * But do not dirty this field too often (once per second is enough)
510 * It is racy as we do not hold a lock, but race is very minor.
512 static inline void tcp_synq_overflow(const struct sock *sk)
514 unsigned int last_overflow;
515 unsigned int now = jiffies;
517 if (sk->sk_reuseport) {
518 struct sock_reuseport *reuse;
520 reuse = rcu_dereference(sk->sk_reuseport_cb);
522 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
523 if (!time_between32(now, last_overflow,
525 WRITE_ONCE(reuse->synq_overflow_ts, now);
530 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
531 if (!time_between32(now, last_overflow, last_overflow + HZ))
532 WRITE_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp, now);
535 /* syncookies: no recent synqueue overflow on this listening socket? */
536 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
538 unsigned int last_overflow;
539 unsigned int now = jiffies;
541 if (sk->sk_reuseport) {
542 struct sock_reuseport *reuse;
544 reuse = rcu_dereference(sk->sk_reuseport_cb);
546 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
547 return !time_between32(now, last_overflow - HZ,
549 TCP_SYNCOOKIE_VALID);
553 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
555 /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
556 * then we're under synflood. However, we have to use
557 * 'last_overflow - HZ' as lower bound. That's because a concurrent
558 * tcp_synq_overflow() could update .ts_recent_stamp after we read
559 * jiffies but before we store .ts_recent_stamp into last_overflow,
560 * which could lead to rejecting a valid syncookie.
562 return !time_between32(now, last_overflow - HZ,
563 last_overflow + TCP_SYNCOOKIE_VALID);
566 static inline u32 tcp_cookie_time(void)
568 u64 val = get_jiffies_64();
570 do_div(val, TCP_SYNCOOKIE_PERIOD);
574 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
576 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
577 u64 cookie_init_timestamp(struct request_sock *req, u64 now);
578 bool cookie_timestamp_decode(const struct net *net,
579 struct tcp_options_received *opt);
580 bool cookie_ecn_ok(const struct tcp_options_received *opt,
581 const struct net *net, const struct dst_entry *dst);
583 /* From net/ipv6/syncookies.c */
584 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
586 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
588 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
589 const struct tcphdr *th, u16 *mssp);
590 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
594 void tcp_skb_entail(struct sock *sk, struct sk_buff *skb);
595 void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb);
596 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
598 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
599 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
600 void tcp_retransmit_timer(struct sock *sk);
601 void tcp_xmit_retransmit_queue(struct sock *);
602 void tcp_simple_retransmit(struct sock *);
603 void tcp_enter_recovery(struct sock *sk, bool ece_ack);
604 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
606 TCP_FRAG_IN_WRITE_QUEUE,
607 TCP_FRAG_IN_RTX_QUEUE,
609 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
610 struct sk_buff *skb, u32 len,
611 unsigned int mss_now, gfp_t gfp);
613 void tcp_send_probe0(struct sock *);
614 void tcp_send_partial(struct sock *);
615 int tcp_write_wakeup(struct sock *, int mib);
616 void tcp_send_fin(struct sock *sk);
617 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
618 int tcp_send_synack(struct sock *);
619 void tcp_push_one(struct sock *, unsigned int mss_now);
620 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
621 void tcp_send_ack(struct sock *sk);
622 void tcp_send_delayed_ack(struct sock *sk);
623 void tcp_send_loss_probe(struct sock *sk);
624 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
625 void tcp_skb_collapse_tstamp(struct sk_buff *skb,
626 const struct sk_buff *next_skb);
629 void tcp_rearm_rto(struct sock *sk);
630 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
631 void tcp_reset(struct sock *sk, struct sk_buff *skb);
632 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
633 void tcp_fin(struct sock *sk);
634 void tcp_check_space(struct sock *sk);
637 void tcp_init_xmit_timers(struct sock *);
638 static inline void tcp_clear_xmit_timers(struct sock *sk)
640 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
643 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
646 inet_csk_clear_xmit_timers(sk);
649 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
650 unsigned int tcp_current_mss(struct sock *sk);
651 u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when);
653 /* Bound MSS / TSO packet size with the half of the window */
654 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
658 /* When peer uses tiny windows, there is no use in packetizing
659 * to sub-MSS pieces for the sake of SWS or making sure there
660 * are enough packets in the pipe for fast recovery.
662 * On the other hand, for extremely large MSS devices, handling
663 * smaller than MSS windows in this way does make sense.
665 if (tp->max_window > TCP_MSS_DEFAULT)
666 cutoff = (tp->max_window >> 1);
668 cutoff = tp->max_window;
670 if (cutoff && pktsize > cutoff)
671 return max_t(int, cutoff, 68U - tp->tcp_header_len);
677 void tcp_get_info(struct sock *, struct tcp_info *);
679 /* Read 'sendfile()'-style from a TCP socket */
680 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
681 sk_read_actor_t recv_actor);
682 int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
683 struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off);
684 void tcp_read_done(struct sock *sk, size_t len);
686 void tcp_initialize_rcv_mss(struct sock *sk);
688 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
689 int tcp_mss_to_mtu(struct sock *sk, int mss);
690 void tcp_mtup_init(struct sock *sk);
692 static inline void tcp_bound_rto(const struct sock *sk)
694 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
695 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
698 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
700 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
703 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
705 /* mptcp hooks are only on the slow path */
706 if (sk_is_mptcp((struct sock *)tp))
709 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
710 ntohl(TCP_FLAG_ACK) |
714 static inline void tcp_fast_path_on(struct tcp_sock *tp)
716 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
719 static inline void tcp_fast_path_check(struct sock *sk)
721 struct tcp_sock *tp = tcp_sk(sk);
723 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
725 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
727 tcp_fast_path_on(tp);
730 /* Compute the actual rto_min value */
731 static inline u32 tcp_rto_min(struct sock *sk)
733 const struct dst_entry *dst = __sk_dst_get(sk);
734 u32 rto_min = inet_csk(sk)->icsk_rto_min;
736 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
737 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
741 static inline u32 tcp_rto_min_us(struct sock *sk)
743 return jiffies_to_usecs(tcp_rto_min(sk));
746 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
748 return dst_metric_locked(dst, RTAX_CC_ALGO);
751 /* Minimum RTT in usec. ~0 means not available. */
752 static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
754 return minmax_get(&tp->rtt_min);
757 /* Compute the actual receive window we are currently advertising.
758 * Rcv_nxt can be after the window if our peer push more data
759 * than the offered window.
761 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
763 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
770 /* Choose a new window, without checks for shrinking, and without
771 * scaling applied to the result. The caller does these things
772 * if necessary. This is a "raw" window selection.
774 u32 __tcp_select_window(struct sock *sk);
776 void tcp_send_window_probe(struct sock *sk);
778 /* TCP uses 32bit jiffies to save some space.
779 * Note that this is different from tcp_time_stamp, which
780 * historically has been the same until linux-4.13.
782 #define tcp_jiffies32 ((u32)jiffies)
785 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
786 * It is no longer tied to jiffies, but to 1 ms clock.
787 * Note: double check if you want to use tcp_jiffies32 instead of this.
789 #define TCP_TS_HZ 1000
791 static inline u64 tcp_clock_ns(void)
793 return ktime_get_ns();
796 static inline u64 tcp_clock_us(void)
798 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
801 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
802 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
804 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
807 /* Convert a nsec timestamp into TCP TSval timestamp (ms based currently) */
808 static inline u32 tcp_ns_to_ts(u64 ns)
810 return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ);
813 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
814 static inline u32 tcp_time_stamp_raw(void)
816 return tcp_ns_to_ts(tcp_clock_ns());
819 void tcp_mstamp_refresh(struct tcp_sock *tp);
821 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
823 return max_t(s64, t1 - t0, 0);
826 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
828 return tcp_ns_to_ts(skb->skb_mstamp_ns);
831 /* provide the departure time in us unit */
832 static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
834 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
838 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
840 #define TCPHDR_FIN 0x01
841 #define TCPHDR_SYN 0x02
842 #define TCPHDR_RST 0x04
843 #define TCPHDR_PSH 0x08
844 #define TCPHDR_ACK 0x10
845 #define TCPHDR_URG 0x20
846 #define TCPHDR_ECE 0x40
847 #define TCPHDR_CWR 0x80
849 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
851 /* This is what the send packet queuing engine uses to pass
852 * TCP per-packet control information to the transmission code.
853 * We also store the host-order sequence numbers in here too.
854 * This is 44 bytes if IPV6 is enabled.
855 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
858 __u32 seq; /* Starting sequence number */
859 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
861 /* Note : tcp_tw_isn is used in input path only
862 * (isn chosen by tcp_timewait_state_process())
864 * tcp_gso_segs/size are used in write queue only,
865 * cf tcp_skb_pcount()/tcp_skb_mss()
873 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
875 __u8 sacked; /* State flags for SACK. */
876 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
877 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
878 #define TCPCB_LOST 0x04 /* SKB is lost */
879 #define TCPCB_TAGBITS 0x07 /* All tag bits */
880 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */
881 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
882 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
885 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
886 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
887 eor:1, /* Is skb MSG_EOR marked? */
888 has_rxtstamp:1, /* SKB has a RX timestamp */
890 __u32 ack_seq; /* Sequence number ACK'd */
893 #define TCPCB_DELIVERED_CE_MASK ((1U<<20) - 1)
894 /* There is space for up to 24 bytes */
895 __u32 is_app_limited:1, /* cwnd not fully used? */
898 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
900 /* start of send pipeline phase */
902 /* when we reached the "delivered" count */
903 u64 delivered_mstamp;
904 } tx; /* only used for outgoing skbs */
906 struct inet_skb_parm h4;
907 #if IS_ENABLED(CONFIG_IPV6)
908 struct inet6_skb_parm h6;
910 } header; /* For incoming skbs */
914 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
916 extern const struct inet_connection_sock_af_ops ipv4_specific;
918 #if IS_ENABLED(CONFIG_IPV6)
919 /* This is the variant of inet6_iif() that must be used by TCP,
920 * as TCP moves IP6CB into a different location in skb->cb[]
922 static inline int tcp_v6_iif(const struct sk_buff *skb)
924 return TCP_SKB_CB(skb)->header.h6.iif;
927 static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
929 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
931 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
934 /* TCP_SKB_CB reference means this can not be used from early demux */
935 static inline int tcp_v6_sdif(const struct sk_buff *skb)
937 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
938 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
939 return TCP_SKB_CB(skb)->header.h6.iif;
944 extern const struct inet_connection_sock_af_ops ipv6_specific;
946 INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
947 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
948 void tcp_v6_early_demux(struct sk_buff *skb);
952 /* TCP_SKB_CB reference means this can not be used from early demux */
953 static inline int tcp_v4_sdif(struct sk_buff *skb)
955 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
956 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
957 return TCP_SKB_CB(skb)->header.h4.iif;
962 /* Due to TSO, an SKB can be composed of multiple actual
963 * packets. To keep these tracked properly, we use this.
965 static inline int tcp_skb_pcount(const struct sk_buff *skb)
967 return TCP_SKB_CB(skb)->tcp_gso_segs;
970 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
972 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
975 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
977 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
980 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
981 static inline int tcp_skb_mss(const struct sk_buff *skb)
983 return TCP_SKB_CB(skb)->tcp_gso_size;
986 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
988 return likely(!TCP_SKB_CB(skb)->eor);
991 static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
992 const struct sk_buff *from)
994 return likely(tcp_skb_can_collapse_to(to) &&
995 mptcp_skb_can_collapse(to, from) &&
996 skb_pure_zcopy_same(to, from));
999 /* Events passed to congestion control interface */
1001 CA_EVENT_TX_START, /* first transmit when no packets in flight */
1002 CA_EVENT_CWND_RESTART, /* congestion window restart */
1003 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
1004 CA_EVENT_LOSS, /* loss timeout */
1005 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
1006 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
1009 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1010 enum tcp_ca_ack_event_flags {
1011 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
1012 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
1013 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
1017 * Interface for adding new TCP congestion control handlers
1019 #define TCP_CA_NAME_MAX 16
1020 #define TCP_CA_MAX 128
1021 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
1023 #define TCP_CA_UNSPEC 0
1025 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1026 #define TCP_CONG_NON_RESTRICTED 0x1
1027 /* Requires ECN/ECT set on all packets */
1028 #define TCP_CONG_NEEDS_ECN 0x2
1029 #define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
1039 /* A rate sample measures the number of (original/retransmitted) data
1040 * packets delivered "delivered" over an interval of time "interval_us".
1041 * The tcp_rate.c code fills in the rate sample, and congestion
1042 * control modules that define a cong_control function to run at the end
1043 * of ACK processing can optionally chose to consult this sample when
1044 * setting cwnd and pacing rate.
1045 * A sample is invalid if "delivered" or "interval_us" is negative.
1047 struct rate_sample {
1048 u64 prior_mstamp; /* starting timestamp for interval */
1049 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1050 u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */
1051 s32 delivered; /* number of packets delivered over interval */
1052 s32 delivered_ce; /* number of packets delivered w/ CE marks*/
1053 long interval_us; /* time for tp->delivered to incr "delivered" */
1054 u32 snd_interval_us; /* snd interval for delivered packets */
1055 u32 rcv_interval_us; /* rcv interval for delivered packets */
1056 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1057 int losses; /* number of packets marked lost upon ACK */
1058 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1059 u32 prior_in_flight; /* in flight before this ACK */
1060 u32 last_end_seq; /* end_seq of most recently ACKed packet */
1061 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1062 bool is_retrans; /* is sample from retransmission? */
1063 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1066 struct tcp_congestion_ops {
1067 /* fast path fields are put first to fill one cache line */
1069 /* return slow start threshold (required) */
1070 u32 (*ssthresh)(struct sock *sk);
1072 /* do new cwnd calculation (required) */
1073 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1075 /* call before changing ca_state (optional) */
1076 void (*set_state)(struct sock *sk, u8 new_state);
1078 /* call when cwnd event occurs (optional) */
1079 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1081 /* call when ack arrives (optional) */
1082 void (*in_ack_event)(struct sock *sk, u32 flags);
1084 /* hook for packet ack accounting (optional) */
1085 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1087 /* override sysctl_tcp_min_tso_segs */
1088 u32 (*min_tso_segs)(struct sock *sk);
1090 /* call when packets are delivered to update cwnd and pacing rate,
1091 * after all the ca_state processing. (optional)
1093 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1096 /* new value of cwnd after loss (required) */
1097 u32 (*undo_cwnd)(struct sock *sk);
1098 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1099 u32 (*sndbuf_expand)(struct sock *sk);
1101 /* control/slow paths put last */
1102 /* get info for inet_diag (optional) */
1103 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1104 union tcp_cc_info *info);
1106 char name[TCP_CA_NAME_MAX];
1107 struct module *owner;
1108 struct list_head list;
1112 /* initialize private data (optional) */
1113 void (*init)(struct sock *sk);
1114 /* cleanup private data (optional) */
1115 void (*release)(struct sock *sk);
1116 } ____cacheline_aligned_in_smp;
1118 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1119 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1120 int tcp_update_congestion_control(struct tcp_congestion_ops *type,
1121 struct tcp_congestion_ops *old_type);
1122 int tcp_validate_congestion_control(struct tcp_congestion_ops *ca);
1124 void tcp_assign_congestion_control(struct sock *sk);
1125 void tcp_init_congestion_control(struct sock *sk);
1126 void tcp_cleanup_congestion_control(struct sock *sk);
1127 int tcp_set_default_congestion_control(struct net *net, const char *name);
1128 void tcp_get_default_congestion_control(struct net *net, char *name);
1129 void tcp_get_available_congestion_control(char *buf, size_t len);
1130 void tcp_get_allowed_congestion_control(char *buf, size_t len);
1131 int tcp_set_allowed_congestion_control(char *allowed);
1132 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1133 bool cap_net_admin);
1134 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1135 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1137 u32 tcp_reno_ssthresh(struct sock *sk);
1138 u32 tcp_reno_undo_cwnd(struct sock *sk);
1139 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1140 extern struct tcp_congestion_ops tcp_reno;
1142 struct tcp_congestion_ops *tcp_ca_find(const char *name);
1143 struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1144 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1146 char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1148 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1154 static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1156 const struct inet_connection_sock *icsk = inet_csk(sk);
1158 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1161 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1163 const struct inet_connection_sock *icsk = inet_csk(sk);
1165 if (icsk->icsk_ca_ops->cwnd_event)
1166 icsk->icsk_ca_ops->cwnd_event(sk, event);
1169 /* From tcp_cong.c */
1170 void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
1172 /* From tcp_rate.c */
1173 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1174 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1175 struct rate_sample *rs);
1176 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1177 bool is_sack_reneg, struct rate_sample *rs);
1178 void tcp_rate_check_app_limited(struct sock *sk);
1180 static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
1182 return t1 > t2 || (t1 == t2 && after(seq1, seq2));
1185 /* These functions determine how the current flow behaves in respect of SACK
1186 * handling. SACK is negotiated with the peer, and therefore it can vary
1187 * between different flows.
1189 * tcp_is_sack - SACK enabled
1190 * tcp_is_reno - No SACK
1192 static inline int tcp_is_sack(const struct tcp_sock *tp)
1194 return likely(tp->rx_opt.sack_ok);
1197 static inline bool tcp_is_reno(const struct tcp_sock *tp)
1199 return !tcp_is_sack(tp);
1202 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1204 return tp->sacked_out + tp->lost_out;
1207 /* This determines how many packets are "in the network" to the best
1208 * of our knowledge. In many cases it is conservative, but where
1209 * detailed information is available from the receiver (via SACK
1210 * blocks etc.) we can make more aggressive calculations.
1212 * Use this for decisions involving congestion control, use just
1213 * tp->packets_out to determine if the send queue is empty or not.
1215 * Read this equation as:
1217 * "Packets sent once on transmission queue" MINUS
1218 * "Packets left network, but not honestly ACKed yet" PLUS
1219 * "Packets fast retransmitted"
1221 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1223 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1226 #define TCP_INFINITE_SSTHRESH 0x7fffffff
1228 static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
1230 return tp->snd_cwnd;
1233 static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
1235 WARN_ON_ONCE((int)val <= 0);
1239 static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1241 return tcp_snd_cwnd(tp) < tp->snd_ssthresh;
1244 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1246 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1249 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1251 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1252 (1 << inet_csk(sk)->icsk_ca_state);
1255 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1256 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1259 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1261 const struct tcp_sock *tp = tcp_sk(sk);
1263 if (tcp_in_cwnd_reduction(sk))
1264 return tp->snd_ssthresh;
1266 return max(tp->snd_ssthresh,
1267 ((tcp_snd_cwnd(tp) >> 1) +
1268 (tcp_snd_cwnd(tp) >> 2)));
1271 /* Use define here intentionally to get WARN_ON location shown at the caller */
1272 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1274 void tcp_enter_cwr(struct sock *sk);
1275 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1277 /* The maximum number of MSS of available cwnd for which TSO defers
1278 * sending if not using sysctl_tcp_tso_win_divisor.
1280 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1285 /* Returns end sequence number of the receiver's advertised window */
1286 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1288 return tp->snd_una + tp->snd_wnd;
1291 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1292 * flexible approach. The RFC suggests cwnd should not be raised unless
1293 * it was fully used previously. And that's exactly what we do in
1294 * congestion avoidance mode. But in slow start we allow cwnd to grow
1295 * as long as the application has used half the cwnd.
1297 * cwnd is 10 (IW10), but application sends 9 frames.
1298 * We allow cwnd to reach 18 when all frames are ACKed.
1299 * This check is safe because it's as aggressive as slow start which already
1300 * risks 100% overshoot. The advantage is that we discourage application to
1301 * either send more filler packets or data to artificially blow up the cwnd
1302 * usage, and allow application-limited process to probe bw more aggressively.
1304 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1306 const struct tcp_sock *tp = tcp_sk(sk);
1308 if (tp->is_cwnd_limited)
1311 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1312 if (tcp_in_slow_start(tp))
1313 return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out;
1318 /* BBR congestion control needs pacing.
1319 * Same remark for SO_MAX_PACING_RATE.
1320 * sch_fq packet scheduler is efficiently handling pacing,
1321 * but is not always installed/used.
1322 * Return true if TCP stack should pace packets itself.
1324 static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1326 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1329 /* Estimates in how many jiffies next packet for this flow can be sent.
1330 * Scheduling a retransmit timer too early would be silly.
1332 static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1334 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1336 return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1339 static inline void tcp_reset_xmit_timer(struct sock *sk,
1342 const unsigned long max_when)
1344 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1348 /* Something is really bad, we could not queue an additional packet,
1349 * because qdisc is full or receiver sent a 0 window, or we are paced.
1350 * We do not want to add fuel to the fire, or abort too early,
1351 * so make sure the timer we arm now is at least 200ms in the future,
1352 * regardless of current icsk_rto value (as it could be ~2ms)
1354 static inline unsigned long tcp_probe0_base(const struct sock *sk)
1356 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1359 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1360 static inline unsigned long tcp_probe0_when(const struct sock *sk,
1361 unsigned long max_when)
1363 u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1,
1364 inet_csk(sk)->icsk_backoff);
1365 u64 when = (u64)tcp_probe0_base(sk) << backoff;
1367 return (unsigned long)min_t(u64, when, max_when);
1370 static inline void tcp_check_probe_timer(struct sock *sk)
1372 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1373 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1374 tcp_probe0_base(sk), TCP_RTO_MAX);
1377 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1382 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1388 * Calculate(/check) TCP checksum
1390 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1391 __be32 daddr, __wsum base)
1393 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1396 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1398 return !skb_csum_unnecessary(skb) &&
1399 __skb_checksum_complete(skb);
1402 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
1403 enum skb_drop_reason *reason);
1406 int tcp_filter(struct sock *sk, struct sk_buff *skb);
1407 void tcp_set_state(struct sock *sk, int state);
1408 void tcp_done(struct sock *sk);
1409 int tcp_abort(struct sock *sk, int err);
1411 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1414 rx_opt->num_sacks = 0;
1417 void tcp_cwnd_restart(struct sock *sk, s32 delta);
1419 static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1421 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1422 struct tcp_sock *tp = tcp_sk(sk);
1425 if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) ||
1426 tp->packets_out || ca_ops->cong_control)
1428 delta = tcp_jiffies32 - tp->lsndtime;
1429 if (delta > inet_csk(sk)->icsk_rto)
1430 tcp_cwnd_restart(sk, delta);
1433 /* Determine a window scaling and initial window to offer. */
1434 void tcp_select_initial_window(const struct sock *sk, int __space,
1435 __u32 mss, __u32 *rcv_wnd,
1436 __u32 *window_clamp, int wscale_ok,
1437 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1439 static inline int tcp_win_from_space(const struct sock *sk, int space)
1441 int tcp_adv_win_scale = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale);
1443 return tcp_adv_win_scale <= 0 ?
1444 (space>>(-tcp_adv_win_scale)) :
1445 space - (space>>tcp_adv_win_scale);
1448 /* Note: caller must be prepared to deal with negative returns */
1449 static inline int tcp_space(const struct sock *sk)
1451 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1452 READ_ONCE(sk->sk_backlog.len) -
1453 atomic_read(&sk->sk_rmem_alloc));
1456 static inline int tcp_full_space(const struct sock *sk)
1458 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1461 static inline void tcp_adjust_rcv_ssthresh(struct sock *sk)
1463 int unused_mem = sk_unused_reserved_mem(sk);
1464 struct tcp_sock *tp = tcp_sk(sk);
1466 tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
1468 tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh,
1469 tcp_win_from_space(sk, unused_mem));
1472 void tcp_cleanup_rbuf(struct sock *sk, int copied);
1474 /* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1475 * If 87.5 % (7/8) of the space has been consumed, we want to override
1476 * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1477 * len/truesize ratio.
1479 static inline bool tcp_rmem_pressure(const struct sock *sk)
1481 int rcvbuf, threshold;
1483 if (tcp_under_memory_pressure(sk))
1486 rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1487 threshold = rcvbuf - (rcvbuf >> 3);
1489 return atomic_read(&sk->sk_rmem_alloc) > threshold;
1492 static inline bool tcp_epollin_ready(const struct sock *sk, int target)
1494 const struct tcp_sock *tp = tcp_sk(sk);
1495 int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);
1500 return (avail >= target) || tcp_rmem_pressure(sk) ||
1501 (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss);
1504 extern void tcp_openreq_init_rwin(struct request_sock *req,
1505 const struct sock *sk_listener,
1506 const struct dst_entry *dst);
1508 void tcp_enter_memory_pressure(struct sock *sk);
1509 void tcp_leave_memory_pressure(struct sock *sk);
1511 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1513 struct net *net = sock_net((struct sock *)tp);
1515 return tp->keepalive_intvl ? :
1516 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
1519 static inline int keepalive_time_when(const struct tcp_sock *tp)
1521 struct net *net = sock_net((struct sock *)tp);
1523 return tp->keepalive_time ? :
1524 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
1527 static inline int keepalive_probes(const struct tcp_sock *tp)
1529 struct net *net = sock_net((struct sock *)tp);
1531 return tp->keepalive_probes ? :
1532 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes);
1535 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1537 const struct inet_connection_sock *icsk = &tp->inet_conn;
1539 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1540 tcp_jiffies32 - tp->rcv_tstamp);
1543 static inline int tcp_fin_time(const struct sock *sk)
1545 int fin_timeout = tcp_sk(sk)->linger2 ? :
1546 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout);
1547 const int rto = inet_csk(sk)->icsk_rto;
1549 if (fin_timeout < (rto << 2) - (rto >> 1))
1550 fin_timeout = (rto << 2) - (rto >> 1);
1555 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1558 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1560 if (unlikely(!time_before32(ktime_get_seconds(),
1561 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1564 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1565 * then following tcp messages have valid values. Ignore 0 value,
1566 * or else 'negative' tsval might forbid us to accept their packets.
1568 if (!rx_opt->ts_recent)
1573 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1576 if (tcp_paws_check(rx_opt, 0))
1579 /* RST segments are not recommended to carry timestamp,
1580 and, if they do, it is recommended to ignore PAWS because
1581 "their cleanup function should take precedence over timestamps."
1582 Certainly, it is mistake. It is necessary to understand the reasons
1583 of this constraint to relax it: if peer reboots, clock may go
1584 out-of-sync and half-open connections will not be reset.
1585 Actually, the problem would be not existing if all
1586 the implementations followed draft about maintaining clock
1587 via reboots. Linux-2.2 DOES NOT!
1589 However, we can relax time bounds for RST segments to MSL.
1591 if (rst && !time_before32(ktime_get_seconds(),
1592 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1597 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1598 int mib_idx, u32 *last_oow_ack_time);
1600 static inline void tcp_mib_init(struct net *net)
1603 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1604 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1605 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1606 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1610 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1612 tp->lost_skb_hint = NULL;
1615 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1617 tcp_clear_retrans_hints_partial(tp);
1618 tp->retransmit_skb_hint = NULL;
1621 union tcp_md5_addr {
1623 #if IS_ENABLED(CONFIG_IPV6)
1628 /* - key database */
1629 struct tcp_md5sig_key {
1630 struct hlist_node node;
1632 u8 family; /* AF_INET or AF_INET6 */
1635 union tcp_md5_addr addr;
1636 int l3index; /* set if key added with L3 scope */
1637 u8 key[TCP_MD5SIG_MAXKEYLEN];
1638 struct rcu_head rcu;
1642 struct tcp_md5sig_info {
1643 struct hlist_head head;
1644 struct rcu_head rcu;
1647 /* - pseudo header */
1648 struct tcp4_pseudohdr {
1656 struct tcp6_pseudohdr {
1657 struct in6_addr saddr;
1658 struct in6_addr daddr;
1660 __be32 protocol; /* including padding */
1663 union tcp_md5sum_block {
1664 struct tcp4_pseudohdr ip4;
1665 #if IS_ENABLED(CONFIG_IPV6)
1666 struct tcp6_pseudohdr ip6;
1670 /* - pool: digest algorithm, hash description and scratch buffer */
1671 struct tcp_md5sig_pool {
1672 struct ahash_request *md5_req;
1677 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1678 const struct sock *sk, const struct sk_buff *skb);
1679 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1680 int family, u8 prefixlen, int l3index, u8 flags,
1681 const u8 *newkey, u8 newkeylen);
1682 int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr,
1683 int family, u8 prefixlen, int l3index,
1684 struct tcp_md5sig_key *key);
1686 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1687 int family, u8 prefixlen, int l3index, u8 flags);
1688 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1689 const struct sock *addr_sk);
1691 #ifdef CONFIG_TCP_MD5SIG
1692 #include <linux/jump_label.h>
1693 extern struct static_key_false_deferred tcp_md5_needed;
1694 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1695 const union tcp_md5_addr *addr,
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)
1701 if (!static_branch_unlikely(&tcp_md5_needed.key))
1703 return __tcp_md5_do_lookup(sk, l3index, addr, family);
1706 enum skb_drop_reason
1707 tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1708 const void *saddr, const void *daddr,
1709 int family, int dif, int sdif);
1712 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1714 static inline struct tcp_md5sig_key *
1715 tcp_md5_do_lookup(const struct sock *sk, int l3index,
1716 const union tcp_md5_addr *addr, int family)
1721 static inline enum skb_drop_reason
1722 tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1723 const void *saddr, const void *daddr,
1724 int family, int dif, int sdif)
1726 return SKB_NOT_DROPPED_YET;
1728 #define tcp_twsk_md5_key(twsk) NULL
1731 bool tcp_alloc_md5sig_pool(void);
1733 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1734 static inline void tcp_put_md5sig_pool(void)
1739 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1740 unsigned int header_len);
1741 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1742 const struct tcp_md5sig_key *key);
1744 /* From tcp_fastopen.c */
1745 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1746 struct tcp_fastopen_cookie *cookie);
1747 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1748 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1750 struct tcp_fastopen_request {
1751 /* Fast Open cookie. Size 0 means a cookie request */
1752 struct tcp_fastopen_cookie cookie;
1753 struct msghdr *data; /* data in MSG_FASTOPEN */
1755 int copied; /* queued in tcp_connect() */
1756 struct ubuf_info *uarg;
1758 void tcp_free_fastopen_req(struct tcp_sock *tp);
1759 void tcp_fastopen_destroy_cipher(struct sock *sk);
1760 void tcp_fastopen_ctx_destroy(struct net *net);
1761 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1762 void *primary_key, void *backup_key);
1763 int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1765 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1766 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1767 struct request_sock *req,
1768 struct tcp_fastopen_cookie *foc,
1769 const struct dst_entry *dst);
1770 void tcp_fastopen_init_key_once(struct net *net);
1771 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1772 struct tcp_fastopen_cookie *cookie);
1773 bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1774 #define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1775 #define TCP_FASTOPEN_KEY_MAX 2
1776 #define TCP_FASTOPEN_KEY_BUF_LENGTH \
1777 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1779 /* Fastopen key context */
1780 struct tcp_fastopen_context {
1781 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1783 struct rcu_head rcu;
1786 void tcp_fastopen_active_disable(struct sock *sk);
1787 bool tcp_fastopen_active_should_disable(struct sock *sk);
1788 void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1789 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1791 /* Caller needs to wrap with rcu_read_(un)lock() */
1793 struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1795 struct tcp_fastopen_context *ctx;
1797 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1799 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1804 bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1805 const struct tcp_fastopen_cookie *orig)
1807 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1808 orig->len == foc->len &&
1809 !memcmp(orig->val, foc->val, foc->len))
1815 int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1820 /* Latencies incurred by various limits for a sender. They are
1821 * chronograph-like stats that are mutually exclusive.
1825 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1826 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1827 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1831 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1832 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1834 /* This helper is needed, because skb->tcp_tsorted_anchor uses
1835 * the same memory storage than skb->destructor/_skb_refdst
1837 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1839 skb->destructor = NULL;
1840 skb->_skb_refdst = 0UL;
1843 #define tcp_skb_tsorted_save(skb) { \
1844 unsigned long _save = skb->_skb_refdst; \
1845 skb->_skb_refdst = 0UL;
1847 #define tcp_skb_tsorted_restore(skb) \
1848 skb->_skb_refdst = _save; \
1851 void tcp_write_queue_purge(struct sock *sk);
1853 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1855 return skb_rb_first(&sk->tcp_rtx_queue);
1858 static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1860 return skb_rb_last(&sk->tcp_rtx_queue);
1863 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1865 return skb_peek_tail(&sk->sk_write_queue);
1868 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1869 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1871 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1873 return skb_peek(&sk->sk_write_queue);
1876 static inline bool tcp_skb_is_last(const struct sock *sk,
1877 const struct sk_buff *skb)
1879 return skb_queue_is_last(&sk->sk_write_queue, skb);
1883 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
1886 * Since the write queue can have a temporary empty skb in it,
1887 * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
1889 static inline bool tcp_write_queue_empty(const struct sock *sk)
1891 const struct tcp_sock *tp = tcp_sk(sk);
1893 return tp->write_seq == tp->snd_nxt;
1896 static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1898 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1901 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1903 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1906 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1908 __skb_queue_tail(&sk->sk_write_queue, skb);
1910 /* Queue it, remembering where we must start sending. */
1911 if (sk->sk_write_queue.next == skb)
1912 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1915 /* Insert new before skb on the write queue of sk. */
1916 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1917 struct sk_buff *skb,
1920 __skb_queue_before(&sk->sk_write_queue, skb, new);
1923 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1925 tcp_skb_tsorted_anchor_cleanup(skb);
1926 __skb_unlink(skb, &sk->sk_write_queue);
1929 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1931 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1933 tcp_skb_tsorted_anchor_cleanup(skb);
1934 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1937 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1939 list_del(&skb->tcp_tsorted_anchor);
1940 tcp_rtx_queue_unlink(skb, sk);
1941 tcp_wmem_free_skb(sk, skb);
1944 static inline void tcp_push_pending_frames(struct sock *sk)
1946 if (tcp_send_head(sk)) {
1947 struct tcp_sock *tp = tcp_sk(sk);
1949 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1953 /* Start sequence of the skb just after the highest skb with SACKed
1954 * bit, valid only if sacked_out > 0 or when the caller has ensured
1955 * validity by itself.
1957 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1959 if (!tp->sacked_out)
1962 if (tp->highest_sack == NULL)
1965 return TCP_SKB_CB(tp->highest_sack)->seq;
1968 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1970 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1973 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1975 return tcp_sk(sk)->highest_sack;
1978 static inline void tcp_highest_sack_reset(struct sock *sk)
1980 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1983 /* Called when old skb is about to be deleted and replaced by new skb */
1984 static inline void tcp_highest_sack_replace(struct sock *sk,
1985 struct sk_buff *old,
1986 struct sk_buff *new)
1988 if (old == tcp_highest_sack(sk))
1989 tcp_sk(sk)->highest_sack = new;
1992 /* This helper checks if socket has IP_TRANSPARENT set */
1993 static inline bool inet_sk_transparent(const struct sock *sk)
1995 switch (sk->sk_state) {
1997 return inet_twsk(sk)->tw_transparent;
1998 case TCP_NEW_SYN_RECV:
1999 return inet_rsk(inet_reqsk(sk))->no_srccheck;
2001 return inet_sk(sk)->transparent;
2004 /* Determines whether this is a thin stream (which may suffer from
2005 * increased latency). Used to trigger latency-reducing mechanisms.
2007 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
2009 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
2013 enum tcp_seq_states {
2014 TCP_SEQ_STATE_LISTENING,
2015 TCP_SEQ_STATE_ESTABLISHED,
2018 void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
2019 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
2020 void tcp_seq_stop(struct seq_file *seq, void *v);
2022 struct tcp_seq_afinfo {
2026 struct tcp_iter_state {
2027 struct seq_net_private p;
2028 enum tcp_seq_states state;
2029 struct sock *syn_wait_sk;
2030 int bucket, offset, sbucket, num;
2034 extern struct request_sock_ops tcp_request_sock_ops;
2035 extern struct request_sock_ops tcp6_request_sock_ops;
2037 void tcp_v4_destroy_sock(struct sock *sk);
2039 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
2040 netdev_features_t features);
2041 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
2042 INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
2043 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
2044 INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
2045 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
2046 int tcp_gro_complete(struct sk_buff *skb);
2048 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
2050 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
2052 struct net *net = sock_net((struct sock *)tp);
2053 return tp->notsent_lowat ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);
2056 bool tcp_stream_memory_free(const struct sock *sk, int wake);
2058 #ifdef CONFIG_PROC_FS
2059 int tcp4_proc_init(void);
2060 void tcp4_proc_exit(void);
2063 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
2064 int tcp_conn_request(struct request_sock_ops *rsk_ops,
2065 const struct tcp_request_sock_ops *af_ops,
2066 struct sock *sk, struct sk_buff *skb);
2068 /* TCP af-specific functions */
2069 struct tcp_sock_af_ops {
2070 #ifdef CONFIG_TCP_MD5SIG
2071 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
2072 const struct sock *addr_sk);
2073 int (*calc_md5_hash)(char *location,
2074 const struct tcp_md5sig_key *md5,
2075 const struct sock *sk,
2076 const struct sk_buff *skb);
2077 int (*md5_parse)(struct sock *sk,
2084 struct tcp_request_sock_ops {
2086 #ifdef CONFIG_TCP_MD5SIG
2087 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2088 const struct sock *addr_sk);
2089 int (*calc_md5_hash) (char *location,
2090 const struct tcp_md5sig_key *md5,
2091 const struct sock *sk,
2092 const struct sk_buff *skb);
2094 #ifdef CONFIG_SYN_COOKIES
2095 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
2098 struct dst_entry *(*route_req)(const struct sock *sk,
2099 struct sk_buff *skb,
2101 struct request_sock *req);
2102 u32 (*init_seq)(const struct sk_buff *skb);
2103 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2104 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2105 struct flowi *fl, struct request_sock *req,
2106 struct tcp_fastopen_cookie *foc,
2107 enum tcp_synack_type synack_type,
2108 struct sk_buff *syn_skb);
2111 extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2112 #if IS_ENABLED(CONFIG_IPV6)
2113 extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2116 #ifdef CONFIG_SYN_COOKIES
2117 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2118 const struct sock *sk, struct sk_buff *skb,
2121 tcp_synq_overflow(sk);
2122 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2123 return ops->cookie_init_seq(skb, mss);
2126 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2127 const struct sock *sk, struct sk_buff *skb,
2134 int tcpv4_offload_init(void);
2136 void tcp_v4_init(void);
2137 void tcp_init(void);
2139 /* tcp_recovery.c */
2140 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2141 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2142 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2144 extern bool tcp_rack_mark_lost(struct sock *sk);
2145 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2147 extern void tcp_rack_reo_timeout(struct sock *sk);
2148 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2153 * Scaling factor for fractions in PLB. For example, tcp_plb_update_state
2154 * expects cong_ratio which represents fraction of traffic that experienced
2155 * congestion over a single RTT. In order to avoid floating point operations,
2156 * this fraction should be mapped to (1 << TCP_PLB_SCALE) and passed in.
2158 #define TCP_PLB_SCALE 8
2160 /* State for PLB (Protective Load Balancing) for a single TCP connection. */
2161 struct tcp_plb_state {
2162 u8 consec_cong_rounds:5, /* consecutive congested rounds */
2164 u32 pause_until; /* jiffies32 when PLB can resume rerouting */
2167 static inline void tcp_plb_init(const struct sock *sk,
2168 struct tcp_plb_state *plb)
2170 plb->consec_cong_rounds = 0;
2171 plb->pause_until = 0;
2173 void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb,
2174 const int cong_ratio);
2175 void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb);
2176 void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb);
2178 /* At how many usecs into the future should the RTO fire? */
2179 static inline s64 tcp_rto_delta_us(const struct sock *sk)
2181 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2182 u32 rto = inet_csk(sk)->icsk_rto;
2183 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2185 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2189 * Save and compile IPv4 options, return a pointer to it
2191 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2192 struct sk_buff *skb)
2194 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2195 struct ip_options_rcu *dopt = NULL;
2198 int opt_size = sizeof(*dopt) + opt->optlen;
2200 dopt = kmalloc(opt_size, GFP_ATOMIC);
2201 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2209 /* locally generated TCP pure ACKs have skb->truesize == 2
2210 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2211 * This is much faster than dissecting the packet to find out.
2212 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2214 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2216 return skb->truesize == 2;
2219 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2224 static inline int tcp_inq(struct sock *sk)
2226 struct tcp_sock *tp = tcp_sk(sk);
2229 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2231 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2233 before(tp->urg_seq, tp->copied_seq) ||
2234 !before(tp->urg_seq, tp->rcv_nxt)) {
2236 answ = tp->rcv_nxt - tp->copied_seq;
2238 /* Subtract 1, if FIN was received */
2239 if (answ && sock_flag(sk, SOCK_DONE))
2242 answ = tp->urg_seq - tp->copied_seq;
2248 int tcp_peek_len(struct socket *sock);
2250 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2254 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2256 /* We update these fields while other threads might
2257 * read them from tcp_get_info()
2259 WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in);
2260 if (skb->len > tcp_hdrlen(skb))
2261 WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in);
2265 * TCP listen path runs lockless.
2266 * We forced "struct sock" to be const qualified to make sure
2267 * we don't modify one of its field by mistake.
2268 * Here, we increment sk_drops which is an atomic_t, so we can safely
2269 * make sock writable again.
2271 static inline void tcp_listendrop(const struct sock *sk)
2273 atomic_inc(&((struct sock *)sk)->sk_drops);
2274 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2277 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2280 * Interface for adding Upper Level Protocols over TCP
2283 #define TCP_ULP_NAME_MAX 16
2284 #define TCP_ULP_MAX 128
2285 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2287 struct tcp_ulp_ops {
2288 struct list_head list;
2290 /* initialize ulp */
2291 int (*init)(struct sock *sk);
2293 void (*update)(struct sock *sk, struct proto *p,
2294 void (*write_space)(struct sock *sk));
2296 void (*release)(struct sock *sk);
2298 int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2299 size_t (*get_info_size)(const struct sock *sk);
2301 void (*clone)(const struct request_sock *req, struct sock *newsk,
2302 const gfp_t priority);
2304 char name[TCP_ULP_NAME_MAX];
2305 struct module *owner;
2307 int tcp_register_ulp(struct tcp_ulp_ops *type);
2308 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2309 int tcp_set_ulp(struct sock *sk, const char *name);
2310 void tcp_get_available_ulp(char *buf, size_t len);
2311 void tcp_cleanup_ulp(struct sock *sk);
2312 void tcp_update_ulp(struct sock *sk, struct proto *p,
2313 void (*write_space)(struct sock *sk));
2315 #define MODULE_ALIAS_TCP_ULP(name) \
2316 __MODULE_INFO(alias, alias_userspace, name); \
2317 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2319 #ifdef CONFIG_NET_SOCK_MSG
2323 #ifdef CONFIG_BPF_SYSCALL
2324 struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
2325 int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
2326 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2327 #endif /* CONFIG_BPF_SYSCALL */
2329 int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
2330 struct sk_msg *msg, u32 bytes, int flags);
2331 #endif /* CONFIG_NET_SOCK_MSG */
2333 #if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)
2334 static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2339 #ifdef CONFIG_CGROUP_BPF
2340 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2341 struct sk_buff *skb,
2342 unsigned int end_offset)
2345 skops->skb_data_end = skb->data + end_offset;
2348 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2349 struct sk_buff *skb,
2350 unsigned int end_offset)
2355 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2356 * is < 0, then the BPF op failed (for example if the loaded BPF
2357 * program does not support the chosen operation or there is no BPF
2361 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2363 struct bpf_sock_ops_kern sock_ops;
2366 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2367 if (sk_fullsock(sk)) {
2368 sock_ops.is_fullsock = 1;
2369 sock_owned_by_me(sk);
2375 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2377 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2379 ret = sock_ops.reply;
2385 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2387 u32 args[2] = {arg1, arg2};
2389 return tcp_call_bpf(sk, op, 2, args);
2392 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2395 u32 args[3] = {arg1, arg2, arg3};
2397 return tcp_call_bpf(sk, op, 3, args);
2401 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2406 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2411 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2419 static inline u32 tcp_timeout_init(struct sock *sk)
2423 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2426 timeout = TCP_TIMEOUT_INIT;
2427 return min_t(int, timeout, TCP_RTO_MAX);
2430 static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2434 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2441 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2443 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2446 static inline void tcp_bpf_rtt(struct sock *sk)
2448 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2449 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2452 #if IS_ENABLED(CONFIG_SMC)
2453 extern struct static_key_false tcp_have_smc;
2456 #if IS_ENABLED(CONFIG_TLS_DEVICE)
2457 void clean_acked_data_enable(struct inet_connection_sock *icsk,
2458 void (*cad)(struct sock *sk, u32 ack_seq));
2459 void clean_acked_data_disable(struct inet_connection_sock *icsk);
2460 void clean_acked_data_flush(void);
2463 DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2464 static inline void tcp_add_tx_delay(struct sk_buff *skb,
2465 const struct tcp_sock *tp)
2467 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2468 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2471 /* Compute Earliest Departure Time for some control packets
2472 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2474 static inline u64 tcp_transmit_time(const struct sock *sk)
2476 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2477 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2478 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2480 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;