2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
6 * Definitions for the TCP module.
8 * Version: @(#)tcp.h 1.0.5 05/23/93
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
21 #define FASTRETRANS_DEBUG 1
23 #include <linux/list.h>
24 #include <linux/tcp.h>
25 #include <linux/bug.h>
26 #include <linux/slab.h>
27 #include <linux/cache.h>
28 #include <linux/percpu.h>
29 #include <linux/skbuff.h>
30 #include <linux/cryptohash.h>
31 #include <linux/kref.h>
32 #include <linux/ktime.h>
34 #include <net/inet_connection_sock.h>
35 #include <net/inet_timewait_sock.h>
36 #include <net/inet_hashtables.h>
37 #include <net/checksum.h>
38 #include <net/request_sock.h>
42 #include <net/tcp_states.h>
43 #include <net/inet_ecn.h>
46 #include <linux/seq_file.h>
47 #include <linux/memcontrol.h>
48 #include <linux/bpf-cgroup.h>
50 extern struct inet_hashinfo tcp_hashinfo
;
52 extern struct percpu_counter tcp_orphan_count
;
53 void tcp_time_wait(struct sock
*sk
, int state
, int timeo
);
55 #define MAX_TCP_HEADER (128 + MAX_HEADER)
56 #define MAX_TCP_OPTION_SPACE 40
57 #define TCP_MIN_SND_MSS 48
58 #define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
61 * Never offer a window over 32767 without using window scaling. Some
62 * poor stacks do signed 16bit maths!
64 #define MAX_TCP_WINDOW 32767U
66 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
67 #define TCP_MIN_MSS 88U
69 /* The least MTU to use for probing */
70 #define TCP_BASE_MSS 1024
72 /* probing interval, default to 10 minutes as per RFC4821 */
73 #define TCP_PROBE_INTERVAL 600
75 /* Specify interval when tcp mtu probing will stop */
76 #define TCP_PROBE_THRESHOLD 8
78 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
79 #define TCP_FASTRETRANS_THRESH 3
81 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
82 #define TCP_MAX_QUICKACKS 16U
84 /* Maximal number of window scale according to RFC1323 */
85 #define TCP_MAX_WSCALE 14U
88 #define TCP_URG_VALID 0x0100
89 #define TCP_URG_NOTYET 0x0200
90 #define TCP_URG_READ 0x0400
92 #define TCP_RETR1 3 /*
93 * This is how many retries it does before it
94 * tries to figure out if the gateway is
95 * down. Minimal RFC value is 3; it corresponds
96 * to ~3sec-8min depending on RTO.
99 #define TCP_RETR2 15 /*
100 * This should take at least
101 * 90 minutes to time out.
102 * RFC1122 says that the limit is 100 sec.
103 * 15 is ~13-30min depending on RTO.
106 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
107 * when active opening a connection.
108 * RFC1122 says the minimum retry MUST
109 * be at least 180secs. Nevertheless
110 * this value is corresponding to
111 * 63secs of retransmission with the
112 * current initial RTO.
115 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
116 * when passive opening a connection.
117 * This is corresponding to 31secs of
118 * retransmission with the current
122 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
123 * state, about 60 seconds */
124 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
125 /* BSD style FIN_WAIT2 deadlock breaker.
126 * It used to be 3min, new value is 60sec,
127 * to combine FIN-WAIT-2 timeout with
131 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
133 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
134 #define TCP_ATO_MIN ((unsigned)(HZ/25))
136 #define TCP_DELACK_MIN 4U
137 #define TCP_ATO_MIN 4U
139 #define TCP_RTO_MAX ((unsigned)(120*HZ))
140 #define TCP_RTO_MIN ((unsigned)(HZ/5))
141 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
142 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
143 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
144 * used as a fallback RTO for the
145 * initial data transmission if no
146 * valid RTT sample has been acquired,
147 * most likely due to retrans in 3WHS.
150 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
151 * for local resources.
153 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
154 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
155 #define TCP_KEEPALIVE_INTVL (75*HZ)
157 #define MAX_TCP_KEEPIDLE 32767
158 #define MAX_TCP_KEEPINTVL 32767
159 #define MAX_TCP_KEEPCNT 127
160 #define MAX_TCP_SYNCNT 127
162 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
164 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
165 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
166 * after this time. It should be equal
167 * (or greater than) TCP_TIMEWAIT_LEN
168 * to provide reliability equal to one
169 * provided by timewait state.
171 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
172 * timestamps. It must be less than
173 * minimal timewait lifetime.
179 #define TCPOPT_NOP 1 /* Padding */
180 #define TCPOPT_EOL 0 /* End of options */
181 #define TCPOPT_MSS 2 /* Segment size negotiating */
182 #define TCPOPT_WINDOW 3 /* Window scaling */
183 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
184 #define TCPOPT_SACK 5 /* SACK Block */
185 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
186 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
187 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
188 #define TCPOPT_EXP 254 /* Experimental */
189 /* Magic number to be after the option value for sharing TCP
190 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
192 #define TCPOPT_FASTOPEN_MAGIC 0xF989
193 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9
199 #define TCPOLEN_MSS 4
200 #define TCPOLEN_WINDOW 3
201 #define TCPOLEN_SACK_PERM 2
202 #define TCPOLEN_TIMESTAMP 10
203 #define TCPOLEN_MD5SIG 18
204 #define TCPOLEN_FASTOPEN_BASE 2
205 #define TCPOLEN_EXP_FASTOPEN_BASE 4
206 #define TCPOLEN_EXP_SMC_BASE 6
208 /* But this is what stacks really send out. */
209 #define TCPOLEN_TSTAMP_ALIGNED 12
210 #define TCPOLEN_WSCALE_ALIGNED 4
211 #define TCPOLEN_SACKPERM_ALIGNED 4
212 #define TCPOLEN_SACK_BASE 2
213 #define TCPOLEN_SACK_BASE_ALIGNED 4
214 #define TCPOLEN_SACK_PERBLOCK 8
215 #define TCPOLEN_MD5SIG_ALIGNED 20
216 #define TCPOLEN_MSS_ALIGNED 4
217 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
219 /* Flags in tp->nonagle */
220 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
221 #define TCP_NAGLE_CORK 2 /* Socket is corked */
222 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
224 /* TCP thin-stream limits */
225 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
227 /* TCP initial congestion window as per rfc6928 */
228 #define TCP_INIT_CWND 10
230 /* Bit Flags for sysctl_tcp_fastopen */
231 #define TFO_CLIENT_ENABLE 1
232 #define TFO_SERVER_ENABLE 2
233 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
235 /* Accept SYN data w/o any cookie option */
236 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
238 /* Force enable TFO on all listeners, i.e., not requiring the
239 * TCP_FASTOPEN socket option.
241 #define TFO_SERVER_WO_SOCKOPT1 0x400
244 /* sysctl variables for tcp */
245 extern int sysctl_tcp_max_orphans
;
246 extern long sysctl_tcp_mem
[3];
248 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
249 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
251 extern atomic_long_t tcp_memory_allocated
;
252 extern struct percpu_counter tcp_sockets_allocated
;
253 extern unsigned long tcp_memory_pressure
;
255 /* optimized version of sk_under_memory_pressure() for TCP sockets */
256 static inline bool tcp_under_memory_pressure(const struct sock
*sk
)
258 if (mem_cgroup_sockets_enabled
&& sk
->sk_memcg
&&
259 mem_cgroup_under_socket_pressure(sk
->sk_memcg
))
262 return tcp_memory_pressure
;
265 * The next routines deal with comparing 32 bit unsigned ints
266 * and worry about wraparound (automatic with unsigned arithmetic).
269 static inline bool before(__u32 seq1
, __u32 seq2
)
271 return (__s32
)(seq1
-seq2
) < 0;
273 #define after(seq2, seq1) before(seq1, seq2)
275 /* is s2<=s1<=s3 ? */
276 static inline bool between(__u32 seq1
, __u32 seq2
, __u32 seq3
)
278 return seq3
- seq2
>= seq1
- seq2
;
281 static inline bool tcp_out_of_memory(struct sock
*sk
)
283 if (sk
->sk_wmem_queued
> SOCK_MIN_SNDBUF
&&
284 sk_memory_allocated(sk
) > sk_prot_mem_limits(sk
, 2))
289 void sk_forced_mem_schedule(struct sock
*sk
, int size
);
291 static inline bool tcp_too_many_orphans(struct sock
*sk
, int shift
)
293 struct percpu_counter
*ocp
= sk
->sk_prot
->orphan_count
;
294 int orphans
= percpu_counter_read_positive(ocp
);
296 if (orphans
<< shift
> sysctl_tcp_max_orphans
) {
297 orphans
= percpu_counter_sum_positive(ocp
);
298 if (orphans
<< shift
> sysctl_tcp_max_orphans
)
304 bool tcp_check_oom(struct sock
*sk
, int shift
);
307 extern struct proto tcp_prot
;
309 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
311 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
312 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
314 void tcp_tasklet_init(void);
316 void tcp_v4_err(struct sk_buff
*skb
, u32
);
318 void tcp_shutdown(struct sock
*sk
, int how
);
320 int tcp_v4_early_demux(struct sk_buff
*skb
);
321 int tcp_v4_rcv(struct sk_buff
*skb
);
323 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock
*tw
);
324 int tcp_sendmsg(struct sock
*sk
, struct msghdr
*msg
, size_t size
);
325 int tcp_sendmsg_locked(struct sock
*sk
, struct msghdr
*msg
, size_t size
);
326 int tcp_sendpage(struct sock
*sk
, struct page
*page
, int offset
, size_t size
,
328 int tcp_sendpage_locked(struct sock
*sk
, struct page
*page
, int offset
,
329 size_t size
, int flags
);
330 ssize_t
do_tcp_sendpages(struct sock
*sk
, struct page
*page
, int offset
,
331 size_t size
, int flags
);
332 void tcp_release_cb(struct sock
*sk
);
333 void tcp_wfree(struct sk_buff
*skb
);
334 void tcp_write_timer_handler(struct sock
*sk
);
335 void tcp_delack_timer_handler(struct sock
*sk
);
336 int tcp_ioctl(struct sock
*sk
, int cmd
, unsigned long arg
);
337 int tcp_rcv_state_process(struct sock
*sk
, struct sk_buff
*skb
);
338 void tcp_rcv_established(struct sock
*sk
, struct sk_buff
*skb
,
339 const struct tcphdr
*th
);
340 void tcp_rcv_space_adjust(struct sock
*sk
);
341 int tcp_twsk_unique(struct sock
*sk
, struct sock
*sktw
, void *twp
);
342 void tcp_twsk_destructor(struct sock
*sk
);
343 ssize_t
tcp_splice_read(struct socket
*sk
, loff_t
*ppos
,
344 struct pipe_inode_info
*pipe
, size_t len
,
347 void tcp_enter_quickack_mode(struct sock
*sk
, unsigned int max_quickacks
);
348 static inline void tcp_dec_quickack_mode(struct sock
*sk
,
349 const unsigned int pkts
)
351 struct inet_connection_sock
*icsk
= inet_csk(sk
);
353 if (icsk
->icsk_ack
.quick
) {
354 if (pkts
>= icsk
->icsk_ack
.quick
) {
355 icsk
->icsk_ack
.quick
= 0;
356 /* Leaving quickack mode we deflate ATO. */
357 icsk
->icsk_ack
.ato
= TCP_ATO_MIN
;
359 icsk
->icsk_ack
.quick
-= pkts
;
364 #define TCP_ECN_QUEUE_CWR 2
365 #define TCP_ECN_DEMAND_CWR 4
366 #define TCP_ECN_SEEN 8
376 enum tcp_tw_status
tcp_timewait_state_process(struct inet_timewait_sock
*tw
,
378 const struct tcphdr
*th
);
379 struct sock
*tcp_check_req(struct sock
*sk
, struct sk_buff
*skb
,
380 struct request_sock
*req
, bool fastopen
);
381 int tcp_child_process(struct sock
*parent
, struct sock
*child
,
382 struct sk_buff
*skb
);
383 void tcp_enter_loss(struct sock
*sk
);
384 void tcp_cwnd_reduction(struct sock
*sk
, int newly_acked_sacked
, int flag
);
385 void tcp_clear_retrans(struct tcp_sock
*tp
);
386 void tcp_update_metrics(struct sock
*sk
);
387 void tcp_init_metrics(struct sock
*sk
);
388 void tcp_metrics_init(void);
389 bool tcp_peer_is_proven(struct request_sock
*req
, struct dst_entry
*dst
);
390 void tcp_close(struct sock
*sk
, long timeout
);
391 void tcp_init_sock(struct sock
*sk
);
392 void tcp_init_transfer(struct sock
*sk
, int bpf_op
);
393 unsigned int tcp_poll(struct file
*file
, struct socket
*sock
,
394 struct poll_table_struct
*wait
);
395 int tcp_getsockopt(struct sock
*sk
, int level
, int optname
,
396 char __user
*optval
, int __user
*optlen
);
397 int tcp_setsockopt(struct sock
*sk
, int level
, int optname
,
398 char __user
*optval
, unsigned int optlen
);
399 int compat_tcp_getsockopt(struct sock
*sk
, int level
, int optname
,
400 char __user
*optval
, int __user
*optlen
);
401 int compat_tcp_setsockopt(struct sock
*sk
, int level
, int optname
,
402 char __user
*optval
, unsigned int optlen
);
403 void tcp_set_keepalive(struct sock
*sk
, int val
);
404 void tcp_syn_ack_timeout(const struct request_sock
*req
);
405 int tcp_recvmsg(struct sock
*sk
, struct msghdr
*msg
, size_t len
, int nonblock
,
406 int flags
, int *addr_len
);
407 void tcp_parse_options(const struct net
*net
, const struct sk_buff
*skb
,
408 struct tcp_options_received
*opt_rx
,
409 int estab
, struct tcp_fastopen_cookie
*foc
);
410 const u8
*tcp_parse_md5sig_option(const struct tcphdr
*th
);
413 * TCP v4 functions exported for the inet6 API
416 void tcp_v4_send_check(struct sock
*sk
, struct sk_buff
*skb
);
417 void tcp_v4_mtu_reduced(struct sock
*sk
);
418 void tcp_req_err(struct sock
*sk
, u32 seq
, bool abort
);
419 int tcp_v4_conn_request(struct sock
*sk
, struct sk_buff
*skb
);
420 struct sock
*tcp_create_openreq_child(const struct sock
*sk
,
421 struct request_sock
*req
,
422 struct sk_buff
*skb
);
423 void tcp_ca_openreq_child(struct sock
*sk
, const struct dst_entry
*dst
);
424 struct sock
*tcp_v4_syn_recv_sock(const struct sock
*sk
, struct sk_buff
*skb
,
425 struct request_sock
*req
,
426 struct dst_entry
*dst
,
427 struct request_sock
*req_unhash
,
429 int tcp_v4_do_rcv(struct sock
*sk
, struct sk_buff
*skb
);
430 int tcp_v4_connect(struct sock
*sk
, struct sockaddr
*uaddr
, int addr_len
);
431 int tcp_connect(struct sock
*sk
);
432 enum tcp_synack_type
{
437 struct sk_buff
*tcp_make_synack(const struct sock
*sk
, struct dst_entry
*dst
,
438 struct request_sock
*req
,
439 struct tcp_fastopen_cookie
*foc
,
440 enum tcp_synack_type synack_type
);
441 int tcp_disconnect(struct sock
*sk
, int flags
);
443 void tcp_finish_connect(struct sock
*sk
, struct sk_buff
*skb
);
444 int tcp_send_rcvq(struct sock
*sk
, struct msghdr
*msg
, size_t size
);
445 void inet_sk_rx_dst_set(struct sock
*sk
, const struct sk_buff
*skb
);
447 /* From syncookies.c */
448 struct sock
*tcp_get_cookie_sock(struct sock
*sk
, struct sk_buff
*skb
,
449 struct request_sock
*req
,
450 struct dst_entry
*dst
, u32 tsoff
);
451 int __cookie_v4_check(const struct iphdr
*iph
, const struct tcphdr
*th
,
453 struct sock
*cookie_v4_check(struct sock
*sk
, struct sk_buff
*skb
);
454 #ifdef CONFIG_SYN_COOKIES
456 /* Syncookies use a monotonic timer which increments every 60 seconds.
457 * This counter is used both as a hash input and partially encoded into
458 * the cookie value. A cookie is only validated further if the delta
459 * between the current counter value and the encoded one is less than this,
460 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
461 * the counter advances immediately after a cookie is generated).
463 #define MAX_SYNCOOKIE_AGE 2
464 #define TCP_SYNCOOKIE_PERIOD (60 * HZ)
465 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
467 /* syncookies: remember time of last synqueue overflow
468 * But do not dirty this field too often (once per second is enough)
469 * It is racy as we do not hold a lock, but race is very minor.
471 static inline void tcp_synq_overflow(const struct sock
*sk
)
473 unsigned long last_overflow
= tcp_sk(sk
)->rx_opt
.ts_recent_stamp
;
474 unsigned long now
= jiffies
;
476 if (time_after(now
, last_overflow
+ HZ
))
477 tcp_sk(sk
)->rx_opt
.ts_recent_stamp
= now
;
480 /* syncookies: no recent synqueue overflow on this listening socket? */
481 static inline bool tcp_synq_no_recent_overflow(const struct sock
*sk
)
483 unsigned long last_overflow
= tcp_sk(sk
)->rx_opt
.ts_recent_stamp
;
485 return time_after(jiffies
, last_overflow
+ TCP_SYNCOOKIE_VALID
);
488 static inline u32
tcp_cookie_time(void)
490 u64 val
= get_jiffies_64();
492 do_div(val
, TCP_SYNCOOKIE_PERIOD
);
496 u32
__cookie_v4_init_sequence(const struct iphdr
*iph
, const struct tcphdr
*th
,
498 __u32
cookie_v4_init_sequence(const struct sk_buff
*skb
, __u16
*mss
);
499 u64
cookie_init_timestamp(struct request_sock
*req
);
500 bool cookie_timestamp_decode(const struct net
*net
,
501 struct tcp_options_received
*opt
);
502 bool cookie_ecn_ok(const struct tcp_options_received
*opt
,
503 const struct net
*net
, const struct dst_entry
*dst
);
505 /* From net/ipv6/syncookies.c */
506 int __cookie_v6_check(const struct ipv6hdr
*iph
, const struct tcphdr
*th
,
508 struct sock
*cookie_v6_check(struct sock
*sk
, struct sk_buff
*skb
);
510 u32
__cookie_v6_init_sequence(const struct ipv6hdr
*iph
,
511 const struct tcphdr
*th
, u16
*mssp
);
512 __u32
cookie_v6_init_sequence(const struct sk_buff
*skb
, __u16
*mss
);
516 u32
tcp_tso_autosize(const struct sock
*sk
, unsigned int mss_now
,
518 void __tcp_push_pending_frames(struct sock
*sk
, unsigned int cur_mss
,
520 int __tcp_retransmit_skb(struct sock
*sk
, struct sk_buff
*skb
, int segs
);
521 int tcp_retransmit_skb(struct sock
*sk
, struct sk_buff
*skb
, int segs
);
522 void tcp_retransmit_timer(struct sock
*sk
);
523 void tcp_xmit_retransmit_queue(struct sock
*);
524 void tcp_simple_retransmit(struct sock
*);
525 void tcp_enter_recovery(struct sock
*sk
, bool ece_ack
);
526 int tcp_trim_head(struct sock
*, struct sk_buff
*, u32
);
528 TCP_FRAG_IN_WRITE_QUEUE
,
529 TCP_FRAG_IN_RTX_QUEUE
,
531 int tcp_fragment(struct sock
*sk
, enum tcp_queue tcp_queue
,
532 struct sk_buff
*skb
, u32 len
,
533 unsigned int mss_now
, gfp_t gfp
);
535 void tcp_send_probe0(struct sock
*);
536 void tcp_send_partial(struct sock
*);
537 int tcp_write_wakeup(struct sock
*, int mib
);
538 void tcp_send_fin(struct sock
*sk
);
539 void tcp_send_active_reset(struct sock
*sk
, gfp_t priority
);
540 int tcp_send_synack(struct sock
*);
541 void tcp_push_one(struct sock
*, unsigned int mss_now
);
542 void __tcp_send_ack(struct sock
*sk
, u32 rcv_nxt
);
543 void tcp_send_ack(struct sock
*sk
);
544 void tcp_send_delayed_ack(struct sock
*sk
);
545 void tcp_send_loss_probe(struct sock
*sk
);
546 bool tcp_schedule_loss_probe(struct sock
*sk
, bool advancing_rto
);
547 void tcp_skb_collapse_tstamp(struct sk_buff
*skb
,
548 const struct sk_buff
*next_skb
);
551 void tcp_rearm_rto(struct sock
*sk
);
552 void tcp_synack_rtt_meas(struct sock
*sk
, struct request_sock
*req
);
553 void tcp_reset(struct sock
*sk
);
554 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock
*tp
, struct sk_buff
*skb
);
555 void tcp_fin(struct sock
*sk
);
558 void tcp_init_xmit_timers(struct sock
*);
559 static inline void tcp_clear_xmit_timers(struct sock
*sk
)
561 hrtimer_cancel(&tcp_sk(sk
)->pacing_timer
);
562 inet_csk_clear_xmit_timers(sk
);
565 unsigned int tcp_sync_mss(struct sock
*sk
, u32 pmtu
);
566 unsigned int tcp_current_mss(struct sock
*sk
);
568 /* Bound MSS / TSO packet size with the half of the window */
569 static inline int tcp_bound_to_half_wnd(struct tcp_sock
*tp
, int pktsize
)
573 /* When peer uses tiny windows, there is no use in packetizing
574 * to sub-MSS pieces for the sake of SWS or making sure there
575 * are enough packets in the pipe for fast recovery.
577 * On the other hand, for extremely large MSS devices, handling
578 * smaller than MSS windows in this way does make sense.
580 if (tp
->max_window
> TCP_MSS_DEFAULT
)
581 cutoff
= (tp
->max_window
>> 1);
583 cutoff
= tp
->max_window
;
585 if (cutoff
&& pktsize
> cutoff
)
586 return max_t(int, cutoff
, 68U - tp
->tcp_header_len
);
592 void tcp_get_info(struct sock
*, struct tcp_info
*);
594 /* Read 'sendfile()'-style from a TCP socket */
595 int tcp_read_sock(struct sock
*sk
, read_descriptor_t
*desc
,
596 sk_read_actor_t recv_actor
);
598 void tcp_initialize_rcv_mss(struct sock
*sk
);
600 int tcp_mtu_to_mss(struct sock
*sk
, int pmtu
);
601 int tcp_mss_to_mtu(struct sock
*sk
, int mss
);
602 void tcp_mtup_init(struct sock
*sk
);
603 void tcp_init_buffer_space(struct sock
*sk
);
605 static inline void tcp_bound_rto(const struct sock
*sk
)
607 if (inet_csk(sk
)->icsk_rto
> TCP_RTO_MAX
)
608 inet_csk(sk
)->icsk_rto
= TCP_RTO_MAX
;
611 static inline u32
__tcp_set_rto(const struct tcp_sock
*tp
)
613 return usecs_to_jiffies((tp
->srtt_us
>> 3) + tp
->rttvar_us
);
616 static inline void __tcp_fast_path_on(struct tcp_sock
*tp
, u32 snd_wnd
)
618 tp
->pred_flags
= htonl((tp
->tcp_header_len
<< 26) |
619 ntohl(TCP_FLAG_ACK
) |
623 static inline void tcp_fast_path_on(struct tcp_sock
*tp
)
625 __tcp_fast_path_on(tp
, tp
->snd_wnd
>> tp
->rx_opt
.snd_wscale
);
628 static inline void tcp_fast_path_check(struct sock
*sk
)
630 struct tcp_sock
*tp
= tcp_sk(sk
);
632 if (RB_EMPTY_ROOT(&tp
->out_of_order_queue
) &&
634 atomic_read(&sk
->sk_rmem_alloc
) < sk
->sk_rcvbuf
&&
636 tcp_fast_path_on(tp
);
639 /* Compute the actual rto_min value */
640 static inline u32
tcp_rto_min(struct sock
*sk
)
642 const struct dst_entry
*dst
= __sk_dst_get(sk
);
643 u32 rto_min
= TCP_RTO_MIN
;
645 if (dst
&& dst_metric_locked(dst
, RTAX_RTO_MIN
))
646 rto_min
= dst_metric_rtt(dst
, RTAX_RTO_MIN
);
650 static inline u32
tcp_rto_min_us(struct sock
*sk
)
652 return jiffies_to_usecs(tcp_rto_min(sk
));
655 static inline bool tcp_ca_dst_locked(const struct dst_entry
*dst
)
657 return dst_metric_locked(dst
, RTAX_CC_ALGO
);
660 /* Minimum RTT in usec. ~0 means not available. */
661 static inline u32
tcp_min_rtt(const struct tcp_sock
*tp
)
663 return minmax_get(&tp
->rtt_min
);
666 /* Compute the actual receive window we are currently advertising.
667 * Rcv_nxt can be after the window if our peer push more data
668 * than the offered window.
670 static inline u32
tcp_receive_window(const struct tcp_sock
*tp
)
672 s32 win
= tp
->rcv_wup
+ tp
->rcv_wnd
- tp
->rcv_nxt
;
679 /* Choose a new window, without checks for shrinking, and without
680 * scaling applied to the result. The caller does these things
681 * if necessary. This is a "raw" window selection.
683 u32
__tcp_select_window(struct sock
*sk
);
685 void tcp_send_window_probe(struct sock
*sk
);
687 /* TCP uses 32bit jiffies to save some space.
688 * Note that this is different from tcp_time_stamp, which
689 * historically has been the same until linux-4.13.
691 #define tcp_jiffies32 ((u32)jiffies)
694 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
695 * It is no longer tied to jiffies, but to 1 ms clock.
696 * Note: double check if you want to use tcp_jiffies32 instead of this.
698 #define TCP_TS_HZ 1000
700 static inline u64
tcp_clock_ns(void)
702 return local_clock();
705 static inline u64
tcp_clock_us(void)
707 return div_u64(tcp_clock_ns(), NSEC_PER_USEC
);
710 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
711 static inline u32
tcp_time_stamp(const struct tcp_sock
*tp
)
713 return div_u64(tp
->tcp_mstamp
, USEC_PER_SEC
/ TCP_TS_HZ
);
716 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
717 static inline u32
tcp_time_stamp_raw(void)
719 return div_u64(tcp_clock_ns(), NSEC_PER_SEC
/ TCP_TS_HZ
);
723 /* Refresh 1us clock of a TCP socket,
724 * ensuring monotically increasing values.
726 static inline void tcp_mstamp_refresh(struct tcp_sock
*tp
)
728 u64 val
= tcp_clock_us();
730 if (val
> tp
->tcp_mstamp
)
731 tp
->tcp_mstamp
= val
;
734 static inline u32
tcp_stamp_us_delta(u64 t1
, u64 t0
)
736 return max_t(s64
, t1
- t0
, 0);
739 static inline u32
tcp_skb_timestamp(const struct sk_buff
*skb
)
741 return div_u64(skb
->skb_mstamp
, USEC_PER_SEC
/ TCP_TS_HZ
);
745 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
747 #define TCPHDR_FIN 0x01
748 #define TCPHDR_SYN 0x02
749 #define TCPHDR_RST 0x04
750 #define TCPHDR_PSH 0x08
751 #define TCPHDR_ACK 0x10
752 #define TCPHDR_URG 0x20
753 #define TCPHDR_ECE 0x40
754 #define TCPHDR_CWR 0x80
756 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
758 /* This is what the send packet queuing engine uses to pass
759 * TCP per-packet control information to the transmission code.
760 * We also store the host-order sequence numbers in here too.
761 * This is 44 bytes if IPV6 is enabled.
762 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
765 __u32 seq
; /* Starting sequence number */
766 __u32 end_seq
; /* SEQ + FIN + SYN + datalen */
768 /* Note : tcp_tw_isn is used in input path only
769 * (isn chosen by tcp_timewait_state_process())
771 * tcp_gso_segs/size are used in write queue only,
772 * cf tcp_skb_pcount()/tcp_skb_mss()
780 __u8 tcp_flags
; /* TCP header flags. (tcp[13]) */
782 __u8 sacked
; /* State flags for SACK. */
783 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
784 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
785 #define TCPCB_LOST 0x04 /* SKB is lost */
786 #define TCPCB_TAGBITS 0x07 /* All tag bits */
787 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
788 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
789 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
792 __u8 ip_dsfield
; /* IPv4 tos or IPv6 dsfield */
793 __u8 txstamp_ack
:1, /* Record TX timestamp for ack? */
794 eor
:1, /* Is skb MSG_EOR marked? */
795 has_rxtstamp
:1, /* SKB has a RX timestamp */
797 __u32 ack_seq
; /* Sequence number ACK'd */
800 /* There is space for up to 24 bytes */
801 __u32 in_flight
:30,/* Bytes in flight at transmit */
802 is_app_limited
:1, /* cwnd not fully used? */
804 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
806 /* start of send pipeline phase */
808 /* when we reached the "delivered" count */
809 u64 delivered_mstamp
;
810 } tx
; /* only used for outgoing skbs */
812 struct inet_skb_parm h4
;
813 #if IS_ENABLED(CONFIG_IPV6)
814 struct inet6_skb_parm h6
;
816 } header
; /* For incoming skbs */
826 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
829 #if IS_ENABLED(CONFIG_IPV6)
830 /* This is the variant of inet6_iif() that must be used by TCP,
831 * as TCP moves IP6CB into a different location in skb->cb[]
833 static inline int tcp_v6_iif(const struct sk_buff
*skb
)
835 return TCP_SKB_CB(skb
)->header
.h6
.iif
;
838 static inline int tcp_v6_iif_l3_slave(const struct sk_buff
*skb
)
840 bool l3_slave
= ipv6_l3mdev_skb(TCP_SKB_CB(skb
)->header
.h6
.flags
);
842 return l3_slave
? skb
->skb_iif
: TCP_SKB_CB(skb
)->header
.h6
.iif
;
845 /* TCP_SKB_CB reference means this can not be used from early demux */
846 static inline int tcp_v6_sdif(const struct sk_buff
*skb
)
848 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
849 if (skb
&& ipv6_l3mdev_skb(TCP_SKB_CB(skb
)->header
.h6
.flags
))
850 return TCP_SKB_CB(skb
)->header
.h6
.iif
;
856 static inline bool inet_exact_dif_match(struct net
*net
, struct sk_buff
*skb
)
858 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
859 if (!net
->ipv4
.sysctl_tcp_l3mdev_accept
&&
860 skb
&& ipv4_l3mdev_skb(IPCB(skb
)->flags
))
866 /* TCP_SKB_CB reference means this can not be used from early demux */
867 static inline int tcp_v4_sdif(struct sk_buff
*skb
)
869 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
870 if (skb
&& ipv4_l3mdev_skb(TCP_SKB_CB(skb
)->header
.h4
.flags
))
871 return TCP_SKB_CB(skb
)->header
.h4
.iif
;
876 /* Due to TSO, an SKB can be composed of multiple actual
877 * packets. To keep these tracked properly, we use this.
879 static inline int tcp_skb_pcount(const struct sk_buff
*skb
)
881 return TCP_SKB_CB(skb
)->tcp_gso_segs
;
884 static inline void tcp_skb_pcount_set(struct sk_buff
*skb
, int segs
)
886 TCP_SKB_CB(skb
)->tcp_gso_segs
= segs
;
889 static inline void tcp_skb_pcount_add(struct sk_buff
*skb
, int segs
)
891 TCP_SKB_CB(skb
)->tcp_gso_segs
+= segs
;
894 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
895 static inline int tcp_skb_mss(const struct sk_buff
*skb
)
897 return TCP_SKB_CB(skb
)->tcp_gso_size
;
900 static inline bool tcp_skb_can_collapse_to(const struct sk_buff
*skb
)
902 return likely(!TCP_SKB_CB(skb
)->eor
);
905 /* Events passed to congestion control interface */
907 CA_EVENT_TX_START
, /* first transmit when no packets in flight */
908 CA_EVENT_CWND_RESTART
, /* congestion window restart */
909 CA_EVENT_COMPLETE_CWR
, /* end of congestion recovery */
910 CA_EVENT_LOSS
, /* loss timeout */
911 CA_EVENT_ECN_NO_CE
, /* ECT set, but not CE marked */
912 CA_EVENT_ECN_IS_CE
, /* received CE marked IP packet */
913 CA_EVENT_DELAYED_ACK
, /* Delayed ack is sent */
914 CA_EVENT_NON_DELAYED_ACK
,
917 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
918 enum tcp_ca_ack_event_flags
{
919 CA_ACK_SLOWPATH
= (1 << 0), /* In slow path processing */
920 CA_ACK_WIN_UPDATE
= (1 << 1), /* ACK updated window */
921 CA_ACK_ECE
= (1 << 2), /* ECE bit is set on ack */
925 * Interface for adding new TCP congestion control handlers
927 #define TCP_CA_NAME_MAX 16
928 #define TCP_CA_MAX 128
929 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
931 #define TCP_CA_UNSPEC 0
933 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
934 #define TCP_CONG_NON_RESTRICTED 0x1
935 /* Requires ECN/ECT set on all packets */
936 #define TCP_CONG_NEEDS_ECN 0x2
946 /* A rate sample measures the number of (original/retransmitted) data
947 * packets delivered "delivered" over an interval of time "interval_us".
948 * The tcp_rate.c code fills in the rate sample, and congestion
949 * control modules that define a cong_control function to run at the end
950 * of ACK processing can optionally chose to consult this sample when
951 * setting cwnd and pacing rate.
952 * A sample is invalid if "delivered" or "interval_us" is negative.
955 u64 prior_mstamp
; /* starting timestamp for interval */
956 u32 prior_delivered
; /* tp->delivered at "prior_mstamp" */
957 s32 delivered
; /* number of packets delivered over interval */
958 long interval_us
; /* time for tp->delivered to incr "delivered" */
959 long rtt_us
; /* RTT of last (S)ACKed packet (or -1) */
960 int losses
; /* number of packets marked lost upon ACK */
961 u32 acked_sacked
; /* number of packets newly (S)ACKed upon ACK */
962 u32 prior_in_flight
; /* in flight before this ACK */
963 bool is_app_limited
; /* is sample from packet with bubble in pipe? */
964 bool is_retrans
; /* is sample from retransmission? */
967 struct tcp_congestion_ops
{
968 struct list_head list
;
972 /* initialize private data (optional) */
973 void (*init
)(struct sock
*sk
);
974 /* cleanup private data (optional) */
975 void (*release
)(struct sock
*sk
);
977 /* return slow start threshold (required) */
978 u32 (*ssthresh
)(struct sock
*sk
);
979 /* do new cwnd calculation (required) */
980 void (*cong_avoid
)(struct sock
*sk
, u32 ack
, u32 acked
);
981 /* call before changing ca_state (optional) */
982 void (*set_state
)(struct sock
*sk
, u8 new_state
);
983 /* call when cwnd event occurs (optional) */
984 void (*cwnd_event
)(struct sock
*sk
, enum tcp_ca_event ev
);
985 /* call when ack arrives (optional) */
986 void (*in_ack_event
)(struct sock
*sk
, u32 flags
);
987 /* new value of cwnd after loss (required) */
988 u32 (*undo_cwnd
)(struct sock
*sk
);
989 /* hook for packet ack accounting (optional) */
990 void (*pkts_acked
)(struct sock
*sk
, const struct ack_sample
*sample
);
991 /* suggest number of segments for each skb to transmit (optional) */
992 u32 (*tso_segs_goal
)(struct sock
*sk
);
993 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
994 u32 (*sndbuf_expand
)(struct sock
*sk
);
995 /* call when packets are delivered to update cwnd and pacing rate,
996 * after all the ca_state processing. (optional)
998 void (*cong_control
)(struct sock
*sk
, const struct rate_sample
*rs
);
999 /* get info for inet_diag (optional) */
1000 size_t (*get_info
)(struct sock
*sk
, u32 ext
, int *attr
,
1001 union tcp_cc_info
*info
);
1003 char name
[TCP_CA_NAME_MAX
];
1004 struct module
*owner
;
1007 int tcp_register_congestion_control(struct tcp_congestion_ops
*type
);
1008 void tcp_unregister_congestion_control(struct tcp_congestion_ops
*type
);
1010 void tcp_assign_congestion_control(struct sock
*sk
);
1011 void tcp_init_congestion_control(struct sock
*sk
);
1012 void tcp_cleanup_congestion_control(struct sock
*sk
);
1013 int tcp_set_default_congestion_control(struct net
*net
, const char *name
);
1014 void tcp_get_default_congestion_control(struct net
*net
, char *name
);
1015 void tcp_get_available_congestion_control(char *buf
, size_t len
);
1016 void tcp_get_allowed_congestion_control(char *buf
, size_t len
);
1017 int tcp_set_allowed_congestion_control(char *allowed
);
1018 int tcp_set_congestion_control(struct sock
*sk
, const char *name
, bool load
, bool reinit
);
1019 u32
tcp_slow_start(struct tcp_sock
*tp
, u32 acked
);
1020 void tcp_cong_avoid_ai(struct tcp_sock
*tp
, u32 w
, u32 acked
);
1022 u32
tcp_reno_ssthresh(struct sock
*sk
);
1023 u32
tcp_reno_undo_cwnd(struct sock
*sk
);
1024 void tcp_reno_cong_avoid(struct sock
*sk
, u32 ack
, u32 acked
);
1025 extern struct tcp_congestion_ops tcp_reno
;
1027 struct tcp_congestion_ops
*tcp_ca_find_key(u32 key
);
1028 u32
tcp_ca_get_key_by_name(struct net
*net
, const char *name
, bool *ecn_ca
);
1030 char *tcp_ca_get_name_by_key(u32 key
, char *buffer
);
1032 static inline char *tcp_ca_get_name_by_key(u32 key
, char *buffer
)
1038 static inline bool tcp_ca_needs_ecn(const struct sock
*sk
)
1040 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
1042 return icsk
->icsk_ca_ops
->flags
& TCP_CONG_NEEDS_ECN
;
1045 static inline void tcp_set_ca_state(struct sock
*sk
, const u8 ca_state
)
1047 struct inet_connection_sock
*icsk
= inet_csk(sk
);
1049 if (icsk
->icsk_ca_ops
->set_state
)
1050 icsk
->icsk_ca_ops
->set_state(sk
, ca_state
);
1051 icsk
->icsk_ca_state
= ca_state
;
1054 static inline void tcp_ca_event(struct sock
*sk
, const enum tcp_ca_event event
)
1056 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
1058 if (icsk
->icsk_ca_ops
->cwnd_event
)
1059 icsk
->icsk_ca_ops
->cwnd_event(sk
, event
);
1062 /* From tcp_rate.c */
1063 void tcp_rate_skb_sent(struct sock
*sk
, struct sk_buff
*skb
);
1064 void tcp_rate_skb_delivered(struct sock
*sk
, struct sk_buff
*skb
,
1065 struct rate_sample
*rs
);
1066 void tcp_rate_gen(struct sock
*sk
, u32 delivered
, u32 lost
,
1067 bool is_sack_reneg
, struct rate_sample
*rs
);
1068 void tcp_rate_check_app_limited(struct sock
*sk
);
1070 /* These functions determine how the current flow behaves in respect of SACK
1071 * handling. SACK is negotiated with the peer, and therefore it can vary
1072 * between different flows.
1074 * tcp_is_sack - SACK enabled
1075 * tcp_is_reno - No SACK
1077 static inline int tcp_is_sack(const struct tcp_sock
*tp
)
1079 return tp
->rx_opt
.sack_ok
;
1082 static inline bool tcp_is_reno(const struct tcp_sock
*tp
)
1084 return !tcp_is_sack(tp
);
1087 static inline unsigned int tcp_left_out(const struct tcp_sock
*tp
)
1089 return tp
->sacked_out
+ tp
->lost_out
;
1092 /* This determines how many packets are "in the network" to the best
1093 * of our knowledge. In many cases it is conservative, but where
1094 * detailed information is available from the receiver (via SACK
1095 * blocks etc.) we can make more aggressive calculations.
1097 * Use this for decisions involving congestion control, use just
1098 * tp->packets_out to determine if the send queue is empty or not.
1100 * Read this equation as:
1102 * "Packets sent once on transmission queue" MINUS
1103 * "Packets left network, but not honestly ACKed yet" PLUS
1104 * "Packets fast retransmitted"
1106 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock
*tp
)
1108 return tp
->packets_out
- tcp_left_out(tp
) + tp
->retrans_out
;
1111 #define TCP_INFINITE_SSTHRESH 0x7fffffff
1113 static inline bool tcp_in_slow_start(const struct tcp_sock
*tp
)
1115 return tp
->snd_cwnd
< tp
->snd_ssthresh
;
1118 static inline bool tcp_in_initial_slowstart(const struct tcp_sock
*tp
)
1120 return tp
->snd_ssthresh
>= TCP_INFINITE_SSTHRESH
;
1123 static inline bool tcp_in_cwnd_reduction(const struct sock
*sk
)
1125 return (TCPF_CA_CWR
| TCPF_CA_Recovery
) &
1126 (1 << inet_csk(sk
)->icsk_ca_state
);
1129 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1130 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1133 static inline __u32
tcp_current_ssthresh(const struct sock
*sk
)
1135 const struct tcp_sock
*tp
= tcp_sk(sk
);
1137 if (tcp_in_cwnd_reduction(sk
))
1138 return tp
->snd_ssthresh
;
1140 return max(tp
->snd_ssthresh
,
1141 ((tp
->snd_cwnd
>> 1) +
1142 (tp
->snd_cwnd
>> 2)));
1145 /* Use define here intentionally to get WARN_ON location shown at the caller */
1146 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1148 void tcp_enter_cwr(struct sock
*sk
);
1149 __u32
tcp_init_cwnd(const struct tcp_sock
*tp
, const struct dst_entry
*dst
);
1151 /* The maximum number of MSS of available cwnd for which TSO defers
1152 * sending if not using sysctl_tcp_tso_win_divisor.
1154 static inline __u32
tcp_max_tso_deferred_mss(const struct tcp_sock
*tp
)
1159 /* Returns end sequence number of the receiver's advertised window */
1160 static inline u32
tcp_wnd_end(const struct tcp_sock
*tp
)
1162 return tp
->snd_una
+ tp
->snd_wnd
;
1165 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1166 * flexible approach. The RFC suggests cwnd should not be raised unless
1167 * it was fully used previously. And that's exactly what we do in
1168 * congestion avoidance mode. But in slow start we allow cwnd to grow
1169 * as long as the application has used half the cwnd.
1171 * cwnd is 10 (IW10), but application sends 9 frames.
1172 * We allow cwnd to reach 18 when all frames are ACKed.
1173 * This check is safe because it's as aggressive as slow start which already
1174 * risks 100% overshoot. The advantage is that we discourage application to
1175 * either send more filler packets or data to artificially blow up the cwnd
1176 * usage, and allow application-limited process to probe bw more aggressively.
1178 static inline bool tcp_is_cwnd_limited(const struct sock
*sk
)
1180 const struct tcp_sock
*tp
= tcp_sk(sk
);
1182 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1183 if (tcp_in_slow_start(tp
))
1184 return tp
->snd_cwnd
< 2 * tp
->max_packets_out
;
1186 return tp
->is_cwnd_limited
;
1189 /* Something is really bad, we could not queue an additional packet,
1190 * because qdisc is full or receiver sent a 0 window.
1191 * We do not want to add fuel to the fire, or abort too early,
1192 * so make sure the timer we arm now is at least 200ms in the future,
1193 * regardless of current icsk_rto value (as it could be ~2ms)
1195 static inline unsigned long tcp_probe0_base(const struct sock
*sk
)
1197 return max_t(unsigned long, inet_csk(sk
)->icsk_rto
, TCP_RTO_MIN
);
1200 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1201 static inline unsigned long tcp_probe0_when(const struct sock
*sk
,
1202 unsigned long max_when
)
1204 u64 when
= (u64
)tcp_probe0_base(sk
) << inet_csk(sk
)->icsk_backoff
;
1206 return (unsigned long)min_t(u64
, when
, max_when
);
1209 static inline void tcp_check_probe_timer(struct sock
*sk
)
1211 if (!tcp_sk(sk
)->packets_out
&& !inet_csk(sk
)->icsk_pending
)
1212 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_PROBE0
,
1213 tcp_probe0_base(sk
), TCP_RTO_MAX
);
1216 static inline void tcp_init_wl(struct tcp_sock
*tp
, u32 seq
)
1221 static inline void tcp_update_wl(struct tcp_sock
*tp
, u32 seq
)
1227 * Calculate(/check) TCP checksum
1229 static inline __sum16
tcp_v4_check(int len
, __be32 saddr
,
1230 __be32 daddr
, __wsum base
)
1232 return csum_tcpudp_magic(saddr
,daddr
,len
,IPPROTO_TCP
,base
);
1235 static inline __sum16
__tcp_checksum_complete(struct sk_buff
*skb
)
1237 return __skb_checksum_complete(skb
);
1240 static inline bool tcp_checksum_complete(struct sk_buff
*skb
)
1242 return !skb_csum_unnecessary(skb
) &&
1243 __tcp_checksum_complete(skb
);
1246 bool tcp_add_backlog(struct sock
*sk
, struct sk_buff
*skb
);
1247 int tcp_filter(struct sock
*sk
, struct sk_buff
*skb
);
1252 static const char *statename
[]={
1253 "Unused","Established","Syn Sent","Syn Recv",
1254 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1255 "Close Wait","Last ACK","Listen","Closing"
1258 void tcp_set_state(struct sock
*sk
, int state
);
1260 void tcp_done(struct sock
*sk
);
1262 int tcp_abort(struct sock
*sk
, int err
);
1264 static inline void tcp_sack_reset(struct tcp_options_received
*rx_opt
)
1267 rx_opt
->num_sacks
= 0;
1270 u32
tcp_default_init_rwnd(u32 mss
);
1271 void tcp_cwnd_restart(struct sock
*sk
, s32 delta
);
1273 static inline void tcp_slow_start_after_idle_check(struct sock
*sk
)
1275 const struct tcp_congestion_ops
*ca_ops
= inet_csk(sk
)->icsk_ca_ops
;
1276 struct tcp_sock
*tp
= tcp_sk(sk
);
1279 if (!sock_net(sk
)->ipv4
.sysctl_tcp_slow_start_after_idle
|| tp
->packets_out
||
1280 ca_ops
->cong_control
)
1282 delta
= tcp_jiffies32
- tp
->lsndtime
;
1283 if (delta
> inet_csk(sk
)->icsk_rto
)
1284 tcp_cwnd_restart(sk
, delta
);
1287 /* Determine a window scaling and initial window to offer. */
1288 void tcp_select_initial_window(const struct sock
*sk
, int __space
,
1289 __u32 mss
, __u32
*rcv_wnd
,
1290 __u32
*window_clamp
, int wscale_ok
,
1291 __u8
*rcv_wscale
, __u32 init_rcv_wnd
);
1293 static inline int tcp_win_from_space(const struct sock
*sk
, int space
)
1295 int tcp_adv_win_scale
= sock_net(sk
)->ipv4
.sysctl_tcp_adv_win_scale
;
1297 return tcp_adv_win_scale
<= 0 ?
1298 (space
>>(-tcp_adv_win_scale
)) :
1299 space
- (space
>>tcp_adv_win_scale
);
1302 /* Note: caller must be prepared to deal with negative returns */
1303 static inline int tcp_space(const struct sock
*sk
)
1305 return tcp_win_from_space(sk
, sk
->sk_rcvbuf
-
1306 atomic_read(&sk
->sk_rmem_alloc
));
1309 static inline int tcp_full_space(const struct sock
*sk
)
1311 return tcp_win_from_space(sk
, sk
->sk_rcvbuf
);
1314 extern void tcp_openreq_init_rwin(struct request_sock
*req
,
1315 const struct sock
*sk_listener
,
1316 const struct dst_entry
*dst
);
1318 void tcp_enter_memory_pressure(struct sock
*sk
);
1319 void tcp_leave_memory_pressure(struct sock
*sk
);
1321 static inline int keepalive_intvl_when(const struct tcp_sock
*tp
)
1323 struct net
*net
= sock_net((struct sock
*)tp
);
1325 return tp
->keepalive_intvl
? : net
->ipv4
.sysctl_tcp_keepalive_intvl
;
1328 static inline int keepalive_time_when(const struct tcp_sock
*tp
)
1330 struct net
*net
= sock_net((struct sock
*)tp
);
1332 return tp
->keepalive_time
? : net
->ipv4
.sysctl_tcp_keepalive_time
;
1335 static inline int keepalive_probes(const struct tcp_sock
*tp
)
1337 struct net
*net
= sock_net((struct sock
*)tp
);
1339 return tp
->keepalive_probes
? : net
->ipv4
.sysctl_tcp_keepalive_probes
;
1342 static inline u32
keepalive_time_elapsed(const struct tcp_sock
*tp
)
1344 const struct inet_connection_sock
*icsk
= &tp
->inet_conn
;
1346 return min_t(u32
, tcp_jiffies32
- icsk
->icsk_ack
.lrcvtime
,
1347 tcp_jiffies32
- tp
->rcv_tstamp
);
1350 static inline int tcp_fin_time(const struct sock
*sk
)
1352 int fin_timeout
= tcp_sk(sk
)->linger2
? : sock_net(sk
)->ipv4
.sysctl_tcp_fin_timeout
;
1353 const int rto
= inet_csk(sk
)->icsk_rto
;
1355 if (fin_timeout
< (rto
<< 2) - (rto
>> 1))
1356 fin_timeout
= (rto
<< 2) - (rto
>> 1);
1361 static inline bool tcp_paws_check(const struct tcp_options_received
*rx_opt
,
1364 if ((s32
)(rx_opt
->ts_recent
- rx_opt
->rcv_tsval
) <= paws_win
)
1366 if (unlikely(get_seconds() >= rx_opt
->ts_recent_stamp
+ TCP_PAWS_24DAYS
))
1369 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1370 * then following tcp messages have valid values. Ignore 0 value,
1371 * or else 'negative' tsval might forbid us to accept their packets.
1373 if (!rx_opt
->ts_recent
)
1378 static inline bool tcp_paws_reject(const struct tcp_options_received
*rx_opt
,
1381 if (tcp_paws_check(rx_opt
, 0))
1384 /* RST segments are not recommended to carry timestamp,
1385 and, if they do, it is recommended to ignore PAWS because
1386 "their cleanup function should take precedence over timestamps."
1387 Certainly, it is mistake. It is necessary to understand the reasons
1388 of this constraint to relax it: if peer reboots, clock may go
1389 out-of-sync and half-open connections will not be reset.
1390 Actually, the problem would be not existing if all
1391 the implementations followed draft about maintaining clock
1392 via reboots. Linux-2.2 DOES NOT!
1394 However, we can relax time bounds for RST segments to MSL.
1396 if (rst
&& get_seconds() >= rx_opt
->ts_recent_stamp
+ TCP_PAWS_MSL
)
1401 bool tcp_oow_rate_limited(struct net
*net
, const struct sk_buff
*skb
,
1402 int mib_idx
, u32
*last_oow_ack_time
);
1404 static inline void tcp_mib_init(struct net
*net
)
1407 TCP_ADD_STATS(net
, TCP_MIB_RTOALGORITHM
, 1);
1408 TCP_ADD_STATS(net
, TCP_MIB_RTOMIN
, TCP_RTO_MIN
*1000/HZ
);
1409 TCP_ADD_STATS(net
, TCP_MIB_RTOMAX
, TCP_RTO_MAX
*1000/HZ
);
1410 TCP_ADD_STATS(net
, TCP_MIB_MAXCONN
, -1);
1414 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock
*tp
)
1416 tp
->lost_skb_hint
= NULL
;
1419 static inline void tcp_clear_all_retrans_hints(struct tcp_sock
*tp
)
1421 tcp_clear_retrans_hints_partial(tp
);
1422 tp
->retransmit_skb_hint
= NULL
;
1425 union tcp_md5_addr
{
1427 #if IS_ENABLED(CONFIG_IPV6)
1432 /* - key database */
1433 struct tcp_md5sig_key
{
1434 struct hlist_node node
;
1436 u8 family
; /* AF_INET or AF_INET6 */
1437 union tcp_md5_addr addr
;
1439 u8 key
[TCP_MD5SIG_MAXKEYLEN
];
1440 struct rcu_head rcu
;
1444 struct tcp_md5sig_info
{
1445 struct hlist_head head
;
1446 struct rcu_head rcu
;
1449 /* - pseudo header */
1450 struct tcp4_pseudohdr
{
1458 struct tcp6_pseudohdr
{
1459 struct in6_addr saddr
;
1460 struct in6_addr daddr
;
1462 __be32 protocol
; /* including padding */
1465 union tcp_md5sum_block
{
1466 struct tcp4_pseudohdr ip4
;
1467 #if IS_ENABLED(CONFIG_IPV6)
1468 struct tcp6_pseudohdr ip6
;
1472 /* - pool: digest algorithm, hash description and scratch buffer */
1473 struct tcp_md5sig_pool
{
1474 struct ahash_request
*md5_req
;
1479 int tcp_v4_md5_hash_skb(char *md5_hash
, const struct tcp_md5sig_key
*key
,
1480 const struct sock
*sk
, const struct sk_buff
*skb
);
1481 int tcp_md5_do_add(struct sock
*sk
, const union tcp_md5_addr
*addr
,
1482 int family
, u8 prefixlen
, const u8
*newkey
, u8 newkeylen
,
1484 int tcp_md5_do_del(struct sock
*sk
, const union tcp_md5_addr
*addr
,
1485 int family
, u8 prefixlen
);
1486 struct tcp_md5sig_key
*tcp_v4_md5_lookup(const struct sock
*sk
,
1487 const struct sock
*addr_sk
);
1489 #ifdef CONFIG_TCP_MD5SIG
1490 struct tcp_md5sig_key
*tcp_md5_do_lookup(const struct sock
*sk
,
1491 const union tcp_md5_addr
*addr
,
1493 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1495 static inline struct tcp_md5sig_key
*tcp_md5_do_lookup(const struct sock
*sk
,
1496 const union tcp_md5_addr
*addr
,
1501 #define tcp_twsk_md5_key(twsk) NULL
1504 bool tcp_alloc_md5sig_pool(void);
1506 struct tcp_md5sig_pool
*tcp_get_md5sig_pool(void);
1507 static inline void tcp_put_md5sig_pool(void)
1512 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool
*, const struct sk_buff
*,
1513 unsigned int header_len
);
1514 int tcp_md5_hash_key(struct tcp_md5sig_pool
*hp
,
1515 const struct tcp_md5sig_key
*key
);
1517 /* From tcp_fastopen.c */
1518 void tcp_fastopen_cache_get(struct sock
*sk
, u16
*mss
,
1519 struct tcp_fastopen_cookie
*cookie
, int *syn_loss
,
1520 unsigned long *last_syn_loss
);
1521 void tcp_fastopen_cache_set(struct sock
*sk
, u16 mss
,
1522 struct tcp_fastopen_cookie
*cookie
, bool syn_lost
,
1524 struct tcp_fastopen_request
{
1525 /* Fast Open cookie. Size 0 means a cookie request */
1526 struct tcp_fastopen_cookie cookie
;
1527 struct msghdr
*data
; /* data in MSG_FASTOPEN */
1529 int copied
; /* queued in tcp_connect() */
1531 void tcp_free_fastopen_req(struct tcp_sock
*tp
);
1532 void tcp_fastopen_destroy_cipher(struct sock
*sk
);
1533 void tcp_fastopen_ctx_destroy(struct net
*net
);
1534 int tcp_fastopen_reset_cipher(struct net
*net
, struct sock
*sk
,
1535 void *key
, unsigned int len
);
1536 void tcp_fastopen_add_skb(struct sock
*sk
, struct sk_buff
*skb
);
1537 struct sock
*tcp_try_fastopen(struct sock
*sk
, struct sk_buff
*skb
,
1538 struct request_sock
*req
,
1539 struct tcp_fastopen_cookie
*foc
,
1540 const struct dst_entry
*dst
);
1541 void tcp_fastopen_init_key_once(struct net
*net
);
1542 bool tcp_fastopen_cookie_check(struct sock
*sk
, u16
*mss
,
1543 struct tcp_fastopen_cookie
*cookie
);
1544 bool tcp_fastopen_defer_connect(struct sock
*sk
, int *err
);
1545 #define TCP_FASTOPEN_KEY_LENGTH 16
1547 /* Fastopen key context */
1548 struct tcp_fastopen_context
{
1549 struct crypto_cipher
*tfm
;
1550 __u8 key
[TCP_FASTOPEN_KEY_LENGTH
];
1551 struct rcu_head rcu
;
1554 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout
;
1555 void tcp_fastopen_active_disable(struct sock
*sk
);
1556 bool tcp_fastopen_active_should_disable(struct sock
*sk
);
1557 void tcp_fastopen_active_disable_ofo_check(struct sock
*sk
);
1558 void tcp_fastopen_active_timeout_reset(void);
1560 /* Latencies incurred by various limits for a sender. They are
1561 * chronograph-like stats that are mutually exclusive.
1565 TCP_CHRONO_BUSY
, /* Actively sending data (non-empty write queue) */
1566 TCP_CHRONO_RWND_LIMITED
, /* Stalled by insufficient receive window */
1567 TCP_CHRONO_SNDBUF_LIMITED
, /* Stalled by insufficient send buffer */
1571 void tcp_chrono_start(struct sock
*sk
, const enum tcp_chrono type
);
1572 void tcp_chrono_stop(struct sock
*sk
, const enum tcp_chrono type
);
1574 /* This helper is needed, because skb->tcp_tsorted_anchor uses
1575 * the same memory storage than skb->destructor/_skb_refdst
1577 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff
*skb
)
1579 skb
->destructor
= NULL
;
1580 skb
->_skb_refdst
= 0UL;
1583 #define tcp_skb_tsorted_save(skb) { \
1584 unsigned long _save = skb->_skb_refdst; \
1585 skb->_skb_refdst = 0UL;
1587 #define tcp_skb_tsorted_restore(skb) \
1588 skb->_skb_refdst = _save; \
1591 void tcp_write_queue_purge(struct sock
*sk
);
1593 static inline struct sk_buff
*tcp_rtx_queue_head(const struct sock
*sk
)
1595 return skb_rb_first(&sk
->tcp_rtx_queue
);
1598 static inline struct sk_buff
*tcp_write_queue_head(const struct sock
*sk
)
1600 return skb_peek(&sk
->sk_write_queue
);
1603 static inline struct sk_buff
*tcp_write_queue_tail(const struct sock
*sk
)
1605 return skb_peek_tail(&sk
->sk_write_queue
);
1608 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1609 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1611 static inline struct sk_buff
*tcp_send_head(const struct sock
*sk
)
1613 return skb_peek(&sk
->sk_write_queue
);
1616 static inline bool tcp_skb_is_last(const struct sock
*sk
,
1617 const struct sk_buff
*skb
)
1619 return skb_queue_is_last(&sk
->sk_write_queue
, skb
);
1622 static inline bool tcp_write_queue_empty(const struct sock
*sk
)
1624 return skb_queue_empty(&sk
->sk_write_queue
);
1627 static inline bool tcp_rtx_queue_empty(const struct sock
*sk
)
1629 return RB_EMPTY_ROOT(&sk
->tcp_rtx_queue
);
1632 static inline bool tcp_rtx_and_write_queues_empty(const struct sock
*sk
)
1634 return tcp_rtx_queue_empty(sk
) && tcp_write_queue_empty(sk
);
1637 static inline void tcp_check_send_head(struct sock
*sk
, struct sk_buff
*skb_unlinked
)
1639 if (tcp_write_queue_empty(sk
))
1640 tcp_chrono_stop(sk
, TCP_CHRONO_BUSY
);
1643 static inline void __tcp_add_write_queue_tail(struct sock
*sk
, struct sk_buff
*skb
)
1645 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
1648 static inline void tcp_add_write_queue_tail(struct sock
*sk
, struct sk_buff
*skb
)
1650 __tcp_add_write_queue_tail(sk
, skb
);
1652 /* Queue it, remembering where we must start sending. */
1653 if (sk
->sk_write_queue
.next
== skb
)
1654 tcp_chrono_start(sk
, TCP_CHRONO_BUSY
);
1657 /* Insert new before skb on the write queue of sk. */
1658 static inline void tcp_insert_write_queue_before(struct sk_buff
*new,
1659 struct sk_buff
*skb
,
1662 __skb_queue_before(&sk
->sk_write_queue
, skb
, new);
1665 static inline void tcp_unlink_write_queue(struct sk_buff
*skb
, struct sock
*sk
)
1667 tcp_skb_tsorted_anchor_cleanup(skb
);
1668 __skb_unlink(skb
, &sk
->sk_write_queue
);
1671 void tcp_rbtree_insert(struct rb_root
*root
, struct sk_buff
*skb
);
1673 static inline void tcp_rtx_queue_unlink(struct sk_buff
*skb
, struct sock
*sk
)
1675 tcp_skb_tsorted_anchor_cleanup(skb
);
1676 rb_erase(&skb
->rbnode
, &sk
->tcp_rtx_queue
);
1679 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff
*skb
, struct sock
*sk
)
1681 list_del(&skb
->tcp_tsorted_anchor
);
1682 tcp_rtx_queue_unlink(skb
, sk
);
1683 sk_wmem_free_skb(sk
, skb
);
1686 static inline void tcp_push_pending_frames(struct sock
*sk
)
1688 if (tcp_send_head(sk
)) {
1689 struct tcp_sock
*tp
= tcp_sk(sk
);
1691 __tcp_push_pending_frames(sk
, tcp_current_mss(sk
), tp
->nonagle
);
1695 /* Start sequence of the skb just after the highest skb with SACKed
1696 * bit, valid only if sacked_out > 0 or when the caller has ensured
1697 * validity by itself.
1699 static inline u32
tcp_highest_sack_seq(struct tcp_sock
*tp
)
1701 if (!tp
->sacked_out
)
1704 if (tp
->highest_sack
== NULL
)
1707 return TCP_SKB_CB(tp
->highest_sack
)->seq
;
1710 static inline void tcp_advance_highest_sack(struct sock
*sk
, struct sk_buff
*skb
)
1712 tcp_sk(sk
)->highest_sack
= skb_rb_next(skb
);
1715 static inline struct sk_buff
*tcp_highest_sack(struct sock
*sk
)
1717 return tcp_sk(sk
)->highest_sack
;
1720 static inline void tcp_highest_sack_reset(struct sock
*sk
)
1722 tcp_sk(sk
)->highest_sack
= tcp_rtx_queue_head(sk
);
1725 /* Called when old skb is about to be deleted and replaced by new skb */
1726 static inline void tcp_highest_sack_replace(struct sock
*sk
,
1727 struct sk_buff
*old
,
1728 struct sk_buff
*new)
1730 if (old
== tcp_highest_sack(sk
))
1731 tcp_sk(sk
)->highest_sack
= new;
1734 /* This helper checks if socket has IP_TRANSPARENT set */
1735 static inline bool inet_sk_transparent(const struct sock
*sk
)
1737 switch (sk
->sk_state
) {
1739 return inet_twsk(sk
)->tw_transparent
;
1740 case TCP_NEW_SYN_RECV
:
1741 return inet_rsk(inet_reqsk(sk
))->no_srccheck
;
1743 return inet_sk(sk
)->transparent
;
1746 /* Determines whether this is a thin stream (which may suffer from
1747 * increased latency). Used to trigger latency-reducing mechanisms.
1749 static inline bool tcp_stream_is_thin(struct tcp_sock
*tp
)
1751 return tp
->packets_out
< 4 && !tcp_in_initial_slowstart(tp
);
1755 enum tcp_seq_states
{
1756 TCP_SEQ_STATE_LISTENING
,
1757 TCP_SEQ_STATE_ESTABLISHED
,
1760 int tcp_seq_open(struct inode
*inode
, struct file
*file
);
1762 struct tcp_seq_afinfo
{
1765 const struct file_operations
*seq_fops
;
1766 struct seq_operations seq_ops
;
1769 struct tcp_iter_state
{
1770 struct seq_net_private p
;
1772 enum tcp_seq_states state
;
1773 struct sock
*syn_wait_sk
;
1774 int bucket
, offset
, sbucket
, num
;
1778 int tcp_proc_register(struct net
*net
, struct tcp_seq_afinfo
*afinfo
);
1779 void tcp_proc_unregister(struct net
*net
, struct tcp_seq_afinfo
*afinfo
);
1781 extern struct request_sock_ops tcp_request_sock_ops
;
1782 extern struct request_sock_ops tcp6_request_sock_ops
;
1784 void tcp_v4_destroy_sock(struct sock
*sk
);
1786 struct sk_buff
*tcp_gso_segment(struct sk_buff
*skb
,
1787 netdev_features_t features
);
1788 struct sk_buff
**tcp_gro_receive(struct sk_buff
**head
, struct sk_buff
*skb
);
1789 int tcp_gro_complete(struct sk_buff
*skb
);
1791 void __tcp_v4_send_check(struct sk_buff
*skb
, __be32 saddr
, __be32 daddr
);
1793 static inline u32
tcp_notsent_lowat(const struct tcp_sock
*tp
)
1795 struct net
*net
= sock_net((struct sock
*)tp
);
1796 return tp
->notsent_lowat
?: net
->ipv4
.sysctl_tcp_notsent_lowat
;
1799 static inline bool tcp_stream_memory_free(const struct sock
*sk
)
1801 const struct tcp_sock
*tp
= tcp_sk(sk
);
1802 u32 notsent_bytes
= tp
->write_seq
- tp
->snd_nxt
;
1804 return notsent_bytes
< tcp_notsent_lowat(tp
);
1807 #ifdef CONFIG_PROC_FS
1808 int tcp4_proc_init(void);
1809 void tcp4_proc_exit(void);
1812 int tcp_rtx_synack(const struct sock
*sk
, struct request_sock
*req
);
1813 int tcp_conn_request(struct request_sock_ops
*rsk_ops
,
1814 const struct tcp_request_sock_ops
*af_ops
,
1815 struct sock
*sk
, struct sk_buff
*skb
);
1817 /* TCP af-specific functions */
1818 struct tcp_sock_af_ops
{
1819 #ifdef CONFIG_TCP_MD5SIG
1820 struct tcp_md5sig_key
*(*md5_lookup
) (const struct sock
*sk
,
1821 const struct sock
*addr_sk
);
1822 int (*calc_md5_hash
)(char *location
,
1823 const struct tcp_md5sig_key
*md5
,
1824 const struct sock
*sk
,
1825 const struct sk_buff
*skb
);
1826 int (*md5_parse
)(struct sock
*sk
,
1828 char __user
*optval
,
1833 struct tcp_request_sock_ops
{
1835 #ifdef CONFIG_TCP_MD5SIG
1836 struct tcp_md5sig_key
*(*req_md5_lookup
)(const struct sock
*sk
,
1837 const struct sock
*addr_sk
);
1838 int (*calc_md5_hash
) (char *location
,
1839 const struct tcp_md5sig_key
*md5
,
1840 const struct sock
*sk
,
1841 const struct sk_buff
*skb
);
1843 void (*init_req
)(struct request_sock
*req
,
1844 const struct sock
*sk_listener
,
1845 struct sk_buff
*skb
);
1846 #ifdef CONFIG_SYN_COOKIES
1847 __u32 (*cookie_init_seq
)(const struct sk_buff
*skb
,
1850 struct dst_entry
*(*route_req
)(const struct sock
*sk
, struct flowi
*fl
,
1851 const struct request_sock
*req
);
1852 u32 (*init_seq
)(const struct sk_buff
*skb
);
1853 u32 (*init_ts_off
)(const struct net
*net
, const struct sk_buff
*skb
);
1854 int (*send_synack
)(const struct sock
*sk
, struct dst_entry
*dst
,
1855 struct flowi
*fl
, struct request_sock
*req
,
1856 struct tcp_fastopen_cookie
*foc
,
1857 enum tcp_synack_type synack_type
);
1860 #ifdef CONFIG_SYN_COOKIES
1861 static inline __u32
cookie_init_sequence(const struct tcp_request_sock_ops
*ops
,
1862 const struct sock
*sk
, struct sk_buff
*skb
,
1865 tcp_synq_overflow(sk
);
1866 __NET_INC_STATS(sock_net(sk
), LINUX_MIB_SYNCOOKIESSENT
);
1867 return ops
->cookie_init_seq(skb
, mss
);
1870 static inline __u32
cookie_init_sequence(const struct tcp_request_sock_ops
*ops
,
1871 const struct sock
*sk
, struct sk_buff
*skb
,
1878 int tcpv4_offload_init(void);
1880 void tcp_v4_init(void);
1881 void tcp_init(void);
1883 /* tcp_recovery.c */
1884 extern void tcp_rack_mark_lost(struct sock
*sk
);
1885 extern void tcp_rack_advance(struct tcp_sock
*tp
, u8 sacked
, u32 end_seq
,
1887 extern void tcp_rack_reo_timeout(struct sock
*sk
);
1888 extern void tcp_rack_update_reo_wnd(struct sock
*sk
, struct rate_sample
*rs
);
1890 /* At how many usecs into the future should the RTO fire? */
1891 static inline s64
tcp_rto_delta_us(const struct sock
*sk
)
1893 const struct sk_buff
*skb
= tcp_rtx_queue_head(sk
);
1894 u32 rto
= inet_csk(sk
)->icsk_rto
;
1895 u64 rto_time_stamp_us
= skb
->skb_mstamp
+ jiffies_to_usecs(rto
);
1897 return rto_time_stamp_us
- tcp_sk(sk
)->tcp_mstamp
;
1901 * Save and compile IPv4 options, return a pointer to it
1903 static inline struct ip_options_rcu
*tcp_v4_save_options(struct net
*net
,
1904 struct sk_buff
*skb
)
1906 const struct ip_options
*opt
= &TCP_SKB_CB(skb
)->header
.h4
.opt
;
1907 struct ip_options_rcu
*dopt
= NULL
;
1910 int opt_size
= sizeof(*dopt
) + opt
->optlen
;
1912 dopt
= kmalloc(opt_size
, GFP_ATOMIC
);
1913 if (dopt
&& __ip_options_echo(net
, &dopt
->opt
, skb
, opt
)) {
1921 /* locally generated TCP pure ACKs have skb->truesize == 2
1922 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1923 * This is much faster than dissecting the packet to find out.
1924 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1926 static inline bool skb_is_tcp_pure_ack(const struct sk_buff
*skb
)
1928 return skb
->truesize
== 2;
1931 static inline void skb_set_tcp_pure_ack(struct sk_buff
*skb
)
1936 static inline int tcp_inq(struct sock
*sk
)
1938 struct tcp_sock
*tp
= tcp_sk(sk
);
1941 if ((1 << sk
->sk_state
) & (TCPF_SYN_SENT
| TCPF_SYN_RECV
)) {
1943 } else if (sock_flag(sk
, SOCK_URGINLINE
) ||
1945 before(tp
->urg_seq
, tp
->copied_seq
) ||
1946 !before(tp
->urg_seq
, tp
->rcv_nxt
)) {
1948 answ
= tp
->rcv_nxt
- tp
->copied_seq
;
1950 /* Subtract 1, if FIN was received */
1951 if (answ
&& sock_flag(sk
, SOCK_DONE
))
1954 answ
= tp
->urg_seq
- tp
->copied_seq
;
1960 int tcp_peek_len(struct socket
*sock
);
1962 static inline void tcp_segs_in(struct tcp_sock
*tp
, const struct sk_buff
*skb
)
1966 segs_in
= max_t(u16
, 1, skb_shinfo(skb
)->gso_segs
);
1967 tp
->segs_in
+= segs_in
;
1968 if (skb
->len
> tcp_hdrlen(skb
))
1969 tp
->data_segs_in
+= segs_in
;
1973 * TCP listen path runs lockless.
1974 * We forced "struct sock" to be const qualified to make sure
1975 * we don't modify one of its field by mistake.
1976 * Here, we increment sk_drops which is an atomic_t, so we can safely
1977 * make sock writable again.
1979 static inline void tcp_listendrop(const struct sock
*sk
)
1981 atomic_inc(&((struct sock
*)sk
)->sk_drops
);
1982 __NET_INC_STATS(sock_net(sk
), LINUX_MIB_LISTENDROPS
);
1985 enum hrtimer_restart
tcp_pace_kick(struct hrtimer
*timer
);
1988 * Interface for adding Upper Level Protocols over TCP
1991 #define TCP_ULP_NAME_MAX 16
1992 #define TCP_ULP_MAX 128
1993 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
1995 struct tcp_ulp_ops
{
1996 struct list_head list
;
1998 /* initialize ulp */
1999 int (*init
)(struct sock
*sk
);
2001 void (*release
)(struct sock
*sk
);
2003 char name
[TCP_ULP_NAME_MAX
];
2004 struct module
*owner
;
2006 int tcp_register_ulp(struct tcp_ulp_ops
*type
);
2007 void tcp_unregister_ulp(struct tcp_ulp_ops
*type
);
2008 int tcp_set_ulp(struct sock
*sk
, const char *name
);
2009 void tcp_get_available_ulp(char *buf
, size_t len
);
2010 void tcp_cleanup_ulp(struct sock
*sk
);
2012 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2013 * is < 0, then the BPF op failed (for example if the loaded BPF
2014 * program does not support the chosen operation or there is no BPF
2018 static inline int tcp_call_bpf(struct sock
*sk
, int op
)
2020 struct bpf_sock_ops_kern sock_ops
;
2023 if (sk_fullsock(sk
))
2024 sock_owned_by_me(sk
);
2026 memset(&sock_ops
, 0, sizeof(sock_ops
));
2030 ret
= BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops
);
2032 ret
= sock_ops
.reply
;
2038 static inline int tcp_call_bpf(struct sock
*sk
, int op
)
2044 static inline u32
tcp_timeout_init(struct sock
*sk
)
2048 timeout
= tcp_call_bpf(sk
, BPF_SOCK_OPS_TIMEOUT_INIT
);
2051 timeout
= TCP_TIMEOUT_INIT
;
2055 static inline u32
tcp_rwnd_init_bpf(struct sock
*sk
)
2059 rwnd
= tcp_call_bpf(sk
, BPF_SOCK_OPS_RWND_INIT
);
2066 static inline bool tcp_bpf_ca_needs_ecn(struct sock
*sk
)
2068 return (tcp_call_bpf(sk
, BPF_SOCK_OPS_NEEDS_ECN
) == 1);
2071 #if IS_ENABLED(CONFIG_SMC)
2072 extern struct static_key_false tcp_have_smc
;