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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
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.
6 *
7 * Definitions for the TCP module.
8 *
9 * Version: @(#)tcp.h 1.0.5 05/23/93
10 *
11 * Authors: Ross Biro
12 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 */
14#ifndef _TCP_H
15#define _TCP_H
16
17#define FASTRETRANS_DEBUG 1
18
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>
29
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>
36#include <net/sock.h>
37#include <net/snmp.h>
38#include <net/ip.h>
39#include <net/tcp_states.h>
40#include <net/inet_ecn.h>
41#include <net/dst.h>
42#include <net/mptcp.h>
43
44#include <linux/seq_file.h>
45#include <linux/memcontrol.h>
46#include <linux/bpf-cgroup.h>
47#include <linux/siphash.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51DECLARE_PER_CPU(unsigned int, tcp_orphan_count);
52int tcp_orphan_count_sum(void);
53
54void tcp_time_wait(struct sock *sk, int state, int timeo);
55
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)
60
61/*
62 * Never offer a window over 32767 without using window scaling. Some
63 * poor stacks do signed 16bit maths!
64 */
65#define MAX_TCP_WINDOW 32767U
66
67/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68#define TCP_MIN_MSS 88U
69
70/* The initial MTU to use for probing */
71#define TCP_BASE_MSS 1024
72
73/* probing interval, default to 10 minutes as per RFC4821 */
74#define TCP_PROBE_INTERVAL 600
75
76/* Specify interval when tcp mtu probing will stop */
77#define TCP_PROBE_THRESHOLD 8
78
79/* After receiving this amount of duplicate ACKs fast retransmit starts. */
80#define TCP_FASTRETRANS_THRESH 3
81
82/* Maximal number of ACKs sent quickly to accelerate slow-start. */
83#define TCP_MAX_QUICKACKS 16U
84
85/* Maximal number of window scale according to RFC1323 */
86#define TCP_MAX_WSCALE 14U
87
88/* urg_data states */
89#define TCP_URG_VALID 0x0100
90#define TCP_URG_NOTYET 0x0200
91#define TCP_URG_READ 0x0400
92
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.
98 */
99
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.
105 */
106
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.
114 */
115
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
120 * initial RTO.
121 */
122
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
129 * TIME-WAIT timer.
130 */
131#define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
132
133#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
134#if HZ >= 100
135#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
136#define TCP_ATO_MIN ((unsigned)(HZ/25))
137#else
138#define TCP_DELACK_MIN 4U
139#define TCP_ATO_MIN 4U
140#endif
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.
150 */
151
152#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
153 * for local resources.
154 */
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)
158
159#define MAX_TCP_KEEPIDLE 32767
160#define MAX_TCP_KEEPINTVL 32767
161#define MAX_TCP_KEEPCNT 127
162#define MAX_TCP_SYNCNT 127
163
164#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
165
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.
172 */
173#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
174 * timestamps. It must be less than
175 * minimal timewait lifetime.
176 */
177/*
178 * TCP option
179 */
180
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
194 */
195#define TCPOPT_FASTOPEN_MAGIC 0xF989
196#define TCPOPT_SMC_MAGIC 0xE2D4C3D9
197
198/*
199 * TCP option lengths
200 */
201
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
210
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
221
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 */
226
227/* TCP thin-stream limits */
228#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
229
230/* TCP initial congestion window as per rfc6928 */
231#define TCP_INIT_CWND 10
232
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 */
237
238/* Accept SYN data w/o any cookie option */
239#define TFO_SERVER_COOKIE_NOT_REQD 0x200
240
241/* Force enable TFO on all listeners, i.e., not requiring the
242 * TCP_FASTOPEN socket option.
243 */
244#define TFO_SERVER_WO_SOCKOPT1 0x400
245
246
247/* sysctl variables for tcp */
248extern int sysctl_tcp_max_orphans;
249extern long sysctl_tcp_mem[3];
250
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 */
254
255extern atomic_long_t tcp_memory_allocated;
256DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
257
258extern struct percpu_counter tcp_sockets_allocated;
259extern unsigned long tcp_memory_pressure;
260
261/* optimized version of sk_under_memory_pressure() for TCP sockets */
262static inline bool tcp_under_memory_pressure(const struct sock *sk)
263{
264 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
265 mem_cgroup_under_socket_pressure(sk->sk_memcg))
266 return true;
267
268 return READ_ONCE(tcp_memory_pressure);
269}
270/*
271 * The next routines deal with comparing 32 bit unsigned ints
272 * and worry about wraparound (automatic with unsigned arithmetic).
273 */
274
275static inline bool before(__u32 seq1, __u32 seq2)
276{
277 return (__s32)(seq1-seq2) < 0;
278}
279#define after(seq2, seq1) before(seq1, seq2)
280
281/* is s2<=s1<=s3 ? */
282static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
283{
284 return seq3 - seq2 >= seq1 - seq2;
285}
286
287static inline bool tcp_out_of_memory(struct sock *sk)
288{
289 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
290 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
291 return true;
292 return false;
293}
294
295static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
296{
297 sk_wmem_queued_add(sk, -skb->truesize);
298 if (!skb_zcopy_pure(skb))
299 sk_mem_uncharge(sk, skb->truesize);
300 else
301 sk_mem_uncharge(sk, SKB_TRUESIZE(skb_end_offset(skb)));
302 __kfree_skb(skb);
303}
304
305void sk_forced_mem_schedule(struct sock *sk, int size);
306
307bool tcp_check_oom(struct sock *sk, int shift);
308
309
310extern struct proto tcp_prot;
311
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)
316
317void tcp_tasklet_init(void);
318
319int tcp_v4_err(struct sk_buff *skb, u32);
320
321void tcp_shutdown(struct sock *sk, int how);
322
323int tcp_v4_early_demux(struct sk_buff *skb);
324int tcp_v4_rcv(struct sk_buff *skb);
325
326void tcp_remove_empty_skb(struct sock *sk);
327int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
328int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
329int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
330int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
331 size_t size, struct ubuf_info *uarg);
332int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
333 int flags);
334int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
335 size_t size, int flags);
336ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
337 size_t size, int flags);
338int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
339void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
340 int size_goal);
341void tcp_release_cb(struct sock *sk);
342void tcp_wfree(struct sk_buff *skb);
343void tcp_write_timer_handler(struct sock *sk);
344void tcp_delack_timer_handler(struct sock *sk);
345int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
346int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
347void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
348void tcp_rcv_space_adjust(struct sock *sk);
349int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
350void tcp_twsk_destructor(struct sock *sk);
351void tcp_twsk_purge(struct list_head *net_exit_list, int family);
352ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
353 struct pipe_inode_info *pipe, size_t len,
354 unsigned int flags);
355struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
356 bool force_schedule);
357
358void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
359static inline void tcp_dec_quickack_mode(struct sock *sk,
360 const unsigned int pkts)
361{
362 struct inet_connection_sock *icsk = inet_csk(sk);
363
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;
369 } else
370 icsk->icsk_ack.quick -= pkts;
371 }
372}
373
374#define TCP_ECN_OK 1
375#define TCP_ECN_QUEUE_CWR 2
376#define TCP_ECN_DEMAND_CWR 4
377#define TCP_ECN_SEEN 8
378
379enum tcp_tw_status {
380 TCP_TW_SUCCESS = 0,
381 TCP_TW_RST = 1,
382 TCP_TW_ACK = 2,
383 TCP_TW_SYN = 3
384};
385
386
387enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
388 struct sk_buff *skb,
389 const struct tcphdr *th);
390struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
391 struct request_sock *req, bool fastopen,
392 bool *lost_race);
393int tcp_child_process(struct sock *parent, struct sock *child,
394 struct sk_buff *skb);
395void tcp_enter_loss(struct sock *sk);
396void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
397void tcp_clear_retrans(struct tcp_sock *tp);
398void tcp_update_metrics(struct sock *sk);
399void tcp_init_metrics(struct sock *sk);
400void tcp_metrics_init(void);
401bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
402void __tcp_close(struct sock *sk, long timeout);
403void tcp_close(struct sock *sk, long timeout);
404void tcp_init_sock(struct sock *sk);
405void 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);
408int do_tcp_getsockopt(struct sock *sk, int level,
409 int optname, sockptr_t optval, sockptr_t optlen);
410int tcp_getsockopt(struct sock *sk, int level, int optname,
411 char __user *optval, int __user *optlen);
412bool tcp_bpf_bypass_getsockopt(int level, int optname);
413int do_tcp_setsockopt(struct sock *sk, int level, int optname,
414 sockptr_t optval, unsigned int optlen);
415int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
416 unsigned int optlen);
417void tcp_set_keepalive(struct sock *sk, int val);
418void tcp_syn_ack_timeout(const struct request_sock *req);
419int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
420 int flags, int *addr_len);
421int tcp_set_rcvlowat(struct sock *sk, int val);
422int tcp_set_window_clamp(struct sock *sk, int val);
423void tcp_update_recv_tstamps(struct sk_buff *skb,
424 struct scm_timestamping_internal *tss);
425void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
426 struct scm_timestamping_internal *tss);
427void tcp_data_ready(struct sock *sk);
428#ifdef CONFIG_MMU
429int tcp_mmap(struct file *file, struct socket *sock,
430 struct vm_area_struct *vma);
431#endif
432void 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);
435const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
436
437/*
438 * BPF SKB-less helpers
439 */
440u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
441 struct tcphdr *th, u32 *cookie);
442u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
443 struct tcphdr *th, u32 *cookie);
444u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss);
445u16 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);
448/*
449 * TCP v4 functions exported for the inet6 API
450 */
451
452void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
453void tcp_v4_mtu_reduced(struct sock *sk);
454void tcp_req_err(struct sock *sk, u32 seq, bool abort);
455void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
456int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
457struct sock *tcp_create_openreq_child(const struct sock *sk,
458 struct request_sock *req,
459 struct sk_buff *skb);
460void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
461struct 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,
465 bool *own_req);
466int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
467int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
468int tcp_connect(struct sock *sk);
469enum tcp_synack_type {
470 TCP_SYNACK_NORMAL,
471 TCP_SYNACK_FASTOPEN,
472 TCP_SYNACK_COOKIE,
473};
474struct 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);
479int tcp_disconnect(struct sock *sk, int flags);
480
481void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
482int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
483void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
484
485/* From syncookies.c */
486struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
487 struct request_sock *req,
488 struct dst_entry *dst, u32 tsoff);
489int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
490 u32 cookie);
491struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
492struct 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
496
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).
503 */
504#define MAX_SYNCOOKIE_AGE 2
505#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
506#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
507
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.
511 */
512static inline void tcp_synq_overflow(const struct sock *sk)
513{
514 unsigned int last_overflow;
515 unsigned int now = jiffies;
516
517 if (sk->sk_reuseport) {
518 struct sock_reuseport *reuse;
519
520 reuse = rcu_dereference(sk->sk_reuseport_cb);
521 if (likely(reuse)) {
522 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
523 if (!time_between32(now, last_overflow,
524 last_overflow + HZ))
525 WRITE_ONCE(reuse->synq_overflow_ts, now);
526 return;
527 }
528 }
529
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);
533}
534
535/* syncookies: no recent synqueue overflow on this listening socket? */
536static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
537{
538 unsigned int last_overflow;
539 unsigned int now = jiffies;
540
541 if (sk->sk_reuseport) {
542 struct sock_reuseport *reuse;
543
544 reuse = rcu_dereference(sk->sk_reuseport_cb);
545 if (likely(reuse)) {
546 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
547 return !time_between32(now, last_overflow - HZ,
548 last_overflow +
549 TCP_SYNCOOKIE_VALID);
550 }
551 }
552
553 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
554
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.
561 */
562 return !time_between32(now, last_overflow - HZ,
563 last_overflow + TCP_SYNCOOKIE_VALID);
564}
565
566static inline u32 tcp_cookie_time(void)
567{
568 u64 val = get_jiffies_64();
569
570 do_div(val, TCP_SYNCOOKIE_PERIOD);
571 return val;
572}
573
574u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
575 u16 *mssp);
576__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
577u64 cookie_init_timestamp(struct request_sock *req, u64 now);
578bool cookie_timestamp_decode(const struct net *net,
579 struct tcp_options_received *opt);
580bool cookie_ecn_ok(const struct tcp_options_received *opt,
581 const struct net *net, const struct dst_entry *dst);
582
583/* From net/ipv6/syncookies.c */
584int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
585 u32 cookie);
586struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
587
588u32 __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);
591#endif
592/* tcp_output.c */
593
594void tcp_skb_entail(struct sock *sk, struct sk_buff *skb);
595void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb);
596void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
597 int nonagle);
598int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
599int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
600void tcp_retransmit_timer(struct sock *sk);
601void tcp_xmit_retransmit_queue(struct sock *);
602void tcp_simple_retransmit(struct sock *);
603void tcp_enter_recovery(struct sock *sk, bool ece_ack);
604int tcp_trim_head(struct sock *, struct sk_buff *, u32);
605enum tcp_queue {
606 TCP_FRAG_IN_WRITE_QUEUE,
607 TCP_FRAG_IN_RTX_QUEUE,
608};
609int 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);
612
613void tcp_send_probe0(struct sock *);
614void tcp_send_partial(struct sock *);
615int tcp_write_wakeup(struct sock *, int mib);
616void tcp_send_fin(struct sock *sk);
617void tcp_send_active_reset(struct sock *sk, gfp_t priority);
618int tcp_send_synack(struct sock *);
619void tcp_push_one(struct sock *, unsigned int mss_now);
620void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
621void tcp_send_ack(struct sock *sk);
622void tcp_send_delayed_ack(struct sock *sk);
623void tcp_send_loss_probe(struct sock *sk);
624bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
625void tcp_skb_collapse_tstamp(struct sk_buff *skb,
626 const struct sk_buff *next_skb);
627
628/* tcp_input.c */
629void tcp_rearm_rto(struct sock *sk);
630void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
631void tcp_reset(struct sock *sk, struct sk_buff *skb);
632void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
633void tcp_fin(struct sock *sk);
634void tcp_check_space(struct sock *sk);
635
636/* tcp_timer.c */
637void tcp_init_xmit_timers(struct sock *);
638static inline void tcp_clear_xmit_timers(struct sock *sk)
639{
640 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
641 __sock_put(sk);
642
643 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
644 __sock_put(sk);
645
646 inet_csk_clear_xmit_timers(sk);
647}
648
649unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
650unsigned int tcp_current_mss(struct sock *sk);
651u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when);
652
653/* Bound MSS / TSO packet size with the half of the window */
654static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
655{
656 int cutoff;
657
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.
661 *
662 * On the other hand, for extremely large MSS devices, handling
663 * smaller than MSS windows in this way does make sense.
664 */
665 if (tp->max_window > TCP_MSS_DEFAULT)
666 cutoff = (tp->max_window >> 1);
667 else
668 cutoff = tp->max_window;
669
670 if (cutoff && pktsize > cutoff)
671 return max_t(int, cutoff, 68U - tp->tcp_header_len);
672 else
673 return pktsize;
674}
675
676/* tcp.c */
677void tcp_get_info(struct sock *, struct tcp_info *);
678
679/* Read 'sendfile()'-style from a TCP socket */
680int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
681 sk_read_actor_t recv_actor);
682int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
683struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off);
684void tcp_read_done(struct sock *sk, size_t len);
685
686void tcp_initialize_rcv_mss(struct sock *sk);
687
688int tcp_mtu_to_mss(struct sock *sk, int pmtu);
689int tcp_mss_to_mtu(struct sock *sk, int mss);
690void tcp_mtup_init(struct sock *sk);
691
692static inline void tcp_bound_rto(const struct sock *sk)
693{
694 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
695 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
696}
697
698static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
699{
700 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
701}
702
703static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
704{
705 /* mptcp hooks are only on the slow path */
706 if (sk_is_mptcp((struct sock *)tp))
707 return;
708
709 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
710 ntohl(TCP_FLAG_ACK) |
711 snd_wnd);
712}
713
714static inline void tcp_fast_path_on(struct tcp_sock *tp)
715{
716 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
717}
718
719static inline void tcp_fast_path_check(struct sock *sk)
720{
721 struct tcp_sock *tp = tcp_sk(sk);
722
723 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
724 tp->rcv_wnd &&
725 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
726 !tp->urg_data)
727 tcp_fast_path_on(tp);
728}
729
730/* Compute the actual rto_min value */
731static inline u32 tcp_rto_min(struct sock *sk)
732{
733 const struct dst_entry *dst = __sk_dst_get(sk);
734 u32 rto_min = inet_csk(sk)->icsk_rto_min;
735
736 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
737 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
738 return rto_min;
739}
740
741static inline u32 tcp_rto_min_us(struct sock *sk)
742{
743 return jiffies_to_usecs(tcp_rto_min(sk));
744}
745
746static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
747{
748 return dst_metric_locked(dst, RTAX_CC_ALGO);
749}
750
751/* Minimum RTT in usec. ~0 means not available. */
752static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
753{
754 return minmax_get(&tp->rtt_min);
755}
756
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.
760 */
761static inline u32 tcp_receive_window(const struct tcp_sock *tp)
762{
763 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
764
765 if (win < 0)
766 win = 0;
767 return (u32) win;
768}
769
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.
773 */
774u32 __tcp_select_window(struct sock *sk);
775
776void tcp_send_window_probe(struct sock *sk);
777
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.
781 */
782#define tcp_jiffies32 ((u32)jiffies)
783
784/*
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.
788 */
789#define TCP_TS_HZ 1000
790
791static inline u64 tcp_clock_ns(void)
792{
793 return ktime_get_ns();
794}
795
796static inline u64 tcp_clock_us(void)
797{
798 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
799}
800
801/* This should only be used in contexts where tp->tcp_mstamp is up to date */
802static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
803{
804 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
805}
806
807/* Convert a nsec timestamp into TCP TSval timestamp (ms based currently) */
808static inline u32 tcp_ns_to_ts(u64 ns)
809{
810 return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ);
811}
812
813/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
814static inline u32 tcp_time_stamp_raw(void)
815{
816 return tcp_ns_to_ts(tcp_clock_ns());
817}
818
819void tcp_mstamp_refresh(struct tcp_sock *tp);
820
821static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
822{
823 return max_t(s64, t1 - t0, 0);
824}
825
826static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
827{
828 return tcp_ns_to_ts(skb->skb_mstamp_ns);
829}
830
831/* provide the departure time in us unit */
832static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
833{
834 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
835}
836
837
838#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
839
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
848
849#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
850
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.
856 */
857struct tcp_skb_cb {
858 __u32 seq; /* Starting sequence number */
859 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
860 union {
861 /* Note : tcp_tw_isn is used in input path only
862 * (isn chosen by tcp_timewait_state_process())
863 *
864 * tcp_gso_segs/size are used in write queue only,
865 * cf tcp_skb_pcount()/tcp_skb_mss()
866 */
867 __u32 tcp_tw_isn;
868 struct {
869 u16 tcp_gso_segs;
870 u16 tcp_gso_size;
871 };
872 };
873 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
874
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| \
883 TCPCB_REPAIRED)
884
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 */
889 unused:5;
890 __u32 ack_seq; /* Sequence number ACK'd */
891 union {
892 struct {
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? */
896 delivered_ce:20,
897 unused:11;
898 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
899 __u32 delivered;
900 /* start of send pipeline phase */
901 u64 first_tx_mstamp;
902 /* when we reached the "delivered" count */
903 u64 delivered_mstamp;
904 } tx; /* only used for outgoing skbs */
905 union {
906 struct inet_skb_parm h4;
907#if IS_ENABLED(CONFIG_IPV6)
908 struct inet6_skb_parm h6;
909#endif
910 } header; /* For incoming skbs */
911 };
912};
913
914#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
915
916extern const struct inet_connection_sock_af_ops ipv4_specific;
917
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[]
921 */
922static inline int tcp_v6_iif(const struct sk_buff *skb)
923{
924 return TCP_SKB_CB(skb)->header.h6.iif;
925}
926
927static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
928{
929 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
930
931 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
932}
933
934/* TCP_SKB_CB reference means this can not be used from early demux */
935static inline int tcp_v6_sdif(const struct sk_buff *skb)
936{
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;
940#endif
941 return 0;
942}
943
944extern const struct inet_connection_sock_af_ops ipv6_specific;
945
946INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
947INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
948void tcp_v6_early_demux(struct sk_buff *skb);
949
950#endif
951
952/* TCP_SKB_CB reference means this can not be used from early demux */
953static inline int tcp_v4_sdif(struct sk_buff *skb)
954{
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;
958#endif
959 return 0;
960}
961
962/* Due to TSO, an SKB can be composed of multiple actual
963 * packets. To keep these tracked properly, we use this.
964 */
965static inline int tcp_skb_pcount(const struct sk_buff *skb)
966{
967 return TCP_SKB_CB(skb)->tcp_gso_segs;
968}
969
970static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
971{
972 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
973}
974
975static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
976{
977 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
978}
979
980/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
981static inline int tcp_skb_mss(const struct sk_buff *skb)
982{
983 return TCP_SKB_CB(skb)->tcp_gso_size;
984}
985
986static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
987{
988 return likely(!TCP_SKB_CB(skb)->eor);
989}
990
991static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
992 const struct sk_buff *from)
993{
994 return likely(tcp_skb_can_collapse_to(to) &&
995 mptcp_skb_can_collapse(to, from) &&
996 skb_pure_zcopy_same(to, from));
997}
998
999/* Events passed to congestion control interface */
1000enum tcp_ca_event {
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 */
1007};
1008
1009/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1010enum 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 */
1014};
1015
1016/*
1017 * Interface for adding new TCP congestion control handlers
1018 */
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)
1022
1023#define TCP_CA_UNSPEC 0
1024
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)
1030
1031union tcp_cc_info;
1032
1033struct ack_sample {
1034 u32 pkts_acked;
1035 s32 rtt_us;
1036 u32 in_flight;
1037};
1038
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.
1046 */
1047struct 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? */
1064};
1065
1066struct tcp_congestion_ops {
1067/* fast path fields are put first to fill one cache line */
1068
1069 /* return slow start threshold (required) */
1070 u32 (*ssthresh)(struct sock *sk);
1071
1072 /* do new cwnd calculation (required) */
1073 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1074
1075 /* call before changing ca_state (optional) */
1076 void (*set_state)(struct sock *sk, u8 new_state);
1077
1078 /* call when cwnd event occurs (optional) */
1079 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1080
1081 /* call when ack arrives (optional) */
1082 void (*in_ack_event)(struct sock *sk, u32 flags);
1083
1084 /* hook for packet ack accounting (optional) */
1085 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1086
1087 /* override sysctl_tcp_min_tso_segs */
1088 u32 (*min_tso_segs)(struct sock *sk);
1089
1090 /* call when packets are delivered to update cwnd and pacing rate,
1091 * after all the ca_state processing. (optional)
1092 */
1093 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1094
1095
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);
1100
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);
1105
1106 char name[TCP_CA_NAME_MAX];
1107 struct module *owner;
1108 struct list_head list;
1109 u32 key;
1110 u32 flags;
1111
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;
1117
1118int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1119void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1120
1121void tcp_assign_congestion_control(struct sock *sk);
1122void tcp_init_congestion_control(struct sock *sk);
1123void tcp_cleanup_congestion_control(struct sock *sk);
1124int tcp_set_default_congestion_control(struct net *net, const char *name);
1125void tcp_get_default_congestion_control(struct net *net, char *name);
1126void tcp_get_available_congestion_control(char *buf, size_t len);
1127void tcp_get_allowed_congestion_control(char *buf, size_t len);
1128int tcp_set_allowed_congestion_control(char *allowed);
1129int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1130 bool cap_net_admin);
1131u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1132void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1133
1134u32 tcp_reno_ssthresh(struct sock *sk);
1135u32 tcp_reno_undo_cwnd(struct sock *sk);
1136void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1137extern struct tcp_congestion_ops tcp_reno;
1138
1139struct tcp_congestion_ops *tcp_ca_find(const char *name);
1140struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1141u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1142#ifdef CONFIG_INET
1143char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1144#else
1145static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1146{
1147 return NULL;
1148}
1149#endif
1150
1151static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1152{
1153 const struct inet_connection_sock *icsk = inet_csk(sk);
1154
1155 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1156}
1157
1158static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1159{
1160 const struct inet_connection_sock *icsk = inet_csk(sk);
1161
1162 if (icsk->icsk_ca_ops->cwnd_event)
1163 icsk->icsk_ca_ops->cwnd_event(sk, event);
1164}
1165
1166/* From tcp_cong.c */
1167void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
1168
1169/* From tcp_rate.c */
1170void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1171void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1172 struct rate_sample *rs);
1173void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1174 bool is_sack_reneg, struct rate_sample *rs);
1175void tcp_rate_check_app_limited(struct sock *sk);
1176
1177static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
1178{
1179 return t1 > t2 || (t1 == t2 && after(seq1, seq2));
1180}
1181
1182/* These functions determine how the current flow behaves in respect of SACK
1183 * handling. SACK is negotiated with the peer, and therefore it can vary
1184 * between different flows.
1185 *
1186 * tcp_is_sack - SACK enabled
1187 * tcp_is_reno - No SACK
1188 */
1189static inline int tcp_is_sack(const struct tcp_sock *tp)
1190{
1191 return likely(tp->rx_opt.sack_ok);
1192}
1193
1194static inline bool tcp_is_reno(const struct tcp_sock *tp)
1195{
1196 return !tcp_is_sack(tp);
1197}
1198
1199static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1200{
1201 return tp->sacked_out + tp->lost_out;
1202}
1203
1204/* This determines how many packets are "in the network" to the best
1205 * of our knowledge. In many cases it is conservative, but where
1206 * detailed information is available from the receiver (via SACK
1207 * blocks etc.) we can make more aggressive calculations.
1208 *
1209 * Use this for decisions involving congestion control, use just
1210 * tp->packets_out to determine if the send queue is empty or not.
1211 *
1212 * Read this equation as:
1213 *
1214 * "Packets sent once on transmission queue" MINUS
1215 * "Packets left network, but not honestly ACKed yet" PLUS
1216 * "Packets fast retransmitted"
1217 */
1218static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1219{
1220 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1221}
1222
1223#define TCP_INFINITE_SSTHRESH 0x7fffffff
1224
1225static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
1226{
1227 return tp->snd_cwnd;
1228}
1229
1230static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
1231{
1232 WARN_ON_ONCE((int)val <= 0);
1233 tp->snd_cwnd = val;
1234}
1235
1236static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1237{
1238 return tcp_snd_cwnd(tp) < tp->snd_ssthresh;
1239}
1240
1241static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1242{
1243 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1244}
1245
1246static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1247{
1248 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1249 (1 << inet_csk(sk)->icsk_ca_state);
1250}
1251
1252/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1253 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1254 * ssthresh.
1255 */
1256static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1257{
1258 const struct tcp_sock *tp = tcp_sk(sk);
1259
1260 if (tcp_in_cwnd_reduction(sk))
1261 return tp->snd_ssthresh;
1262 else
1263 return max(tp->snd_ssthresh,
1264 ((tcp_snd_cwnd(tp) >> 1) +
1265 (tcp_snd_cwnd(tp) >> 2)));
1266}
1267
1268/* Use define here intentionally to get WARN_ON location shown at the caller */
1269#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1270
1271void tcp_enter_cwr(struct sock *sk);
1272__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1273
1274/* The maximum number of MSS of available cwnd for which TSO defers
1275 * sending if not using sysctl_tcp_tso_win_divisor.
1276 */
1277static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1278{
1279 return 3;
1280}
1281
1282/* Returns end sequence number of the receiver's advertised window */
1283static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1284{
1285 return tp->snd_una + tp->snd_wnd;
1286}
1287
1288/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1289 * flexible approach. The RFC suggests cwnd should not be raised unless
1290 * it was fully used previously. And that's exactly what we do in
1291 * congestion avoidance mode. But in slow start we allow cwnd to grow
1292 * as long as the application has used half the cwnd.
1293 * Example :
1294 * cwnd is 10 (IW10), but application sends 9 frames.
1295 * We allow cwnd to reach 18 when all frames are ACKed.
1296 * This check is safe because it's as aggressive as slow start which already
1297 * risks 100% overshoot. The advantage is that we discourage application to
1298 * either send more filler packets or data to artificially blow up the cwnd
1299 * usage, and allow application-limited process to probe bw more aggressively.
1300 */
1301static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1302{
1303 const struct tcp_sock *tp = tcp_sk(sk);
1304
1305 if (tp->is_cwnd_limited)
1306 return true;
1307
1308 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1309 if (tcp_in_slow_start(tp))
1310 return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out;
1311
1312 return false;
1313}
1314
1315/* BBR congestion control needs pacing.
1316 * Same remark for SO_MAX_PACING_RATE.
1317 * sch_fq packet scheduler is efficiently handling pacing,
1318 * but is not always installed/used.
1319 * Return true if TCP stack should pace packets itself.
1320 */
1321static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1322{
1323 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1324}
1325
1326/* Estimates in how many jiffies next packet for this flow can be sent.
1327 * Scheduling a retransmit timer too early would be silly.
1328 */
1329static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1330{
1331 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1332
1333 return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1334}
1335
1336static inline void tcp_reset_xmit_timer(struct sock *sk,
1337 const int what,
1338 unsigned long when,
1339 const unsigned long max_when)
1340{
1341 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1342 max_when);
1343}
1344
1345/* Something is really bad, we could not queue an additional packet,
1346 * because qdisc is full or receiver sent a 0 window, or we are paced.
1347 * We do not want to add fuel to the fire, or abort too early,
1348 * so make sure the timer we arm now is at least 200ms in the future,
1349 * regardless of current icsk_rto value (as it could be ~2ms)
1350 */
1351static inline unsigned long tcp_probe0_base(const struct sock *sk)
1352{
1353 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1354}
1355
1356/* Variant of inet_csk_rto_backoff() used for zero window probes */
1357static inline unsigned long tcp_probe0_when(const struct sock *sk,
1358 unsigned long max_when)
1359{
1360 u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1,
1361 inet_csk(sk)->icsk_backoff);
1362 u64 when = (u64)tcp_probe0_base(sk) << backoff;
1363
1364 return (unsigned long)min_t(u64, when, max_when);
1365}
1366
1367static inline void tcp_check_probe_timer(struct sock *sk)
1368{
1369 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1370 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1371 tcp_probe0_base(sk), TCP_RTO_MAX);
1372}
1373
1374static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1375{
1376 tp->snd_wl1 = seq;
1377}
1378
1379static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1380{
1381 tp->snd_wl1 = seq;
1382}
1383
1384/*
1385 * Calculate(/check) TCP checksum
1386 */
1387static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1388 __be32 daddr, __wsum base)
1389{
1390 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1391}
1392
1393static inline bool tcp_checksum_complete(struct sk_buff *skb)
1394{
1395 return !skb_csum_unnecessary(skb) &&
1396 __skb_checksum_complete(skb);
1397}
1398
1399bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
1400 enum skb_drop_reason *reason);
1401
1402
1403int tcp_filter(struct sock *sk, struct sk_buff *skb);
1404void tcp_set_state(struct sock *sk, int state);
1405void tcp_done(struct sock *sk);
1406int tcp_abort(struct sock *sk, int err);
1407
1408static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1409{
1410 rx_opt->dsack = 0;
1411 rx_opt->num_sacks = 0;
1412}
1413
1414void tcp_cwnd_restart(struct sock *sk, s32 delta);
1415
1416static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1417{
1418 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1419 struct tcp_sock *tp = tcp_sk(sk);
1420 s32 delta;
1421
1422 if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) ||
1423 tp->packets_out || ca_ops->cong_control)
1424 return;
1425 delta = tcp_jiffies32 - tp->lsndtime;
1426 if (delta > inet_csk(sk)->icsk_rto)
1427 tcp_cwnd_restart(sk, delta);
1428}
1429
1430/* Determine a window scaling and initial window to offer. */
1431void tcp_select_initial_window(const struct sock *sk, int __space,
1432 __u32 mss, __u32 *rcv_wnd,
1433 __u32 *window_clamp, int wscale_ok,
1434 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1435
1436static inline int tcp_win_from_space(const struct sock *sk, int space)
1437{
1438 int tcp_adv_win_scale = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale);
1439
1440 return tcp_adv_win_scale <= 0 ?
1441 (space>>(-tcp_adv_win_scale)) :
1442 space - (space>>tcp_adv_win_scale);
1443}
1444
1445/* Note: caller must be prepared to deal with negative returns */
1446static inline int tcp_space(const struct sock *sk)
1447{
1448 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1449 READ_ONCE(sk->sk_backlog.len) -
1450 atomic_read(&sk->sk_rmem_alloc));
1451}
1452
1453static inline int tcp_full_space(const struct sock *sk)
1454{
1455 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1456}
1457
1458static inline void tcp_adjust_rcv_ssthresh(struct sock *sk)
1459{
1460 int unused_mem = sk_unused_reserved_mem(sk);
1461 struct tcp_sock *tp = tcp_sk(sk);
1462
1463 tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
1464 if (unused_mem)
1465 tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh,
1466 tcp_win_from_space(sk, unused_mem));
1467}
1468
1469void tcp_cleanup_rbuf(struct sock *sk, int copied);
1470
1471/* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1472 * If 87.5 % (7/8) of the space has been consumed, we want to override
1473 * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1474 * len/truesize ratio.
1475 */
1476static inline bool tcp_rmem_pressure(const struct sock *sk)
1477{
1478 int rcvbuf, threshold;
1479
1480 if (tcp_under_memory_pressure(sk))
1481 return true;
1482
1483 rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1484 threshold = rcvbuf - (rcvbuf >> 3);
1485
1486 return atomic_read(&sk->sk_rmem_alloc) > threshold;
1487}
1488
1489static inline bool tcp_epollin_ready(const struct sock *sk, int target)
1490{
1491 const struct tcp_sock *tp = tcp_sk(sk);
1492 int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);
1493
1494 if (avail <= 0)
1495 return false;
1496
1497 return (avail >= target) || tcp_rmem_pressure(sk) ||
1498 (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss);
1499}
1500
1501extern void tcp_openreq_init_rwin(struct request_sock *req,
1502 const struct sock *sk_listener,
1503 const struct dst_entry *dst);
1504
1505void tcp_enter_memory_pressure(struct sock *sk);
1506void tcp_leave_memory_pressure(struct sock *sk);
1507
1508static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1509{
1510 struct net *net = sock_net((struct sock *)tp);
1511
1512 return tp->keepalive_intvl ? :
1513 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
1514}
1515
1516static inline int keepalive_time_when(const struct tcp_sock *tp)
1517{
1518 struct net *net = sock_net((struct sock *)tp);
1519
1520 return tp->keepalive_time ? :
1521 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
1522}
1523
1524static inline int keepalive_probes(const struct tcp_sock *tp)
1525{
1526 struct net *net = sock_net((struct sock *)tp);
1527
1528 return tp->keepalive_probes ? :
1529 READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes);
1530}
1531
1532static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1533{
1534 const struct inet_connection_sock *icsk = &tp->inet_conn;
1535
1536 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1537 tcp_jiffies32 - tp->rcv_tstamp);
1538}
1539
1540static inline int tcp_fin_time(const struct sock *sk)
1541{
1542 int fin_timeout = tcp_sk(sk)->linger2 ? :
1543 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout);
1544 const int rto = inet_csk(sk)->icsk_rto;
1545
1546 if (fin_timeout < (rto << 2) - (rto >> 1))
1547 fin_timeout = (rto << 2) - (rto >> 1);
1548
1549 return fin_timeout;
1550}
1551
1552static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1553 int paws_win)
1554{
1555 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1556 return true;
1557 if (unlikely(!time_before32(ktime_get_seconds(),
1558 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1559 return true;
1560 /*
1561 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1562 * then following tcp messages have valid values. Ignore 0 value,
1563 * or else 'negative' tsval might forbid us to accept their packets.
1564 */
1565 if (!rx_opt->ts_recent)
1566 return true;
1567 return false;
1568}
1569
1570static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1571 int rst)
1572{
1573 if (tcp_paws_check(rx_opt, 0))
1574 return false;
1575
1576 /* RST segments are not recommended to carry timestamp,
1577 and, if they do, it is recommended to ignore PAWS because
1578 "their cleanup function should take precedence over timestamps."
1579 Certainly, it is mistake. It is necessary to understand the reasons
1580 of this constraint to relax it: if peer reboots, clock may go
1581 out-of-sync and half-open connections will not be reset.
1582 Actually, the problem would be not existing if all
1583 the implementations followed draft about maintaining clock
1584 via reboots. Linux-2.2 DOES NOT!
1585
1586 However, we can relax time bounds for RST segments to MSL.
1587 */
1588 if (rst && !time_before32(ktime_get_seconds(),
1589 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1590 return false;
1591 return true;
1592}
1593
1594bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1595 int mib_idx, u32 *last_oow_ack_time);
1596
1597static inline void tcp_mib_init(struct net *net)
1598{
1599 /* See RFC 2012 */
1600 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1601 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1602 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1603 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1604}
1605
1606/* from STCP */
1607static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1608{
1609 tp->lost_skb_hint = NULL;
1610}
1611
1612static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1613{
1614 tcp_clear_retrans_hints_partial(tp);
1615 tp->retransmit_skb_hint = NULL;
1616}
1617
1618union tcp_md5_addr {
1619 struct in_addr a4;
1620#if IS_ENABLED(CONFIG_IPV6)
1621 struct in6_addr a6;
1622#endif
1623};
1624
1625/* - key database */
1626struct tcp_md5sig_key {
1627 struct hlist_node node;
1628 u8 keylen;
1629 u8 family; /* AF_INET or AF_INET6 */
1630 u8 prefixlen;
1631 u8 flags;
1632 union tcp_md5_addr addr;
1633 int l3index; /* set if key added with L3 scope */
1634 u8 key[TCP_MD5SIG_MAXKEYLEN];
1635 struct rcu_head rcu;
1636};
1637
1638/* - sock block */
1639struct tcp_md5sig_info {
1640 struct hlist_head head;
1641 struct rcu_head rcu;
1642};
1643
1644/* - pseudo header */
1645struct tcp4_pseudohdr {
1646 __be32 saddr;
1647 __be32 daddr;
1648 __u8 pad;
1649 __u8 protocol;
1650 __be16 len;
1651};
1652
1653struct tcp6_pseudohdr {
1654 struct in6_addr saddr;
1655 struct in6_addr daddr;
1656 __be32 len;
1657 __be32 protocol; /* including padding */
1658};
1659
1660union tcp_md5sum_block {
1661 struct tcp4_pseudohdr ip4;
1662#if IS_ENABLED(CONFIG_IPV6)
1663 struct tcp6_pseudohdr ip6;
1664#endif
1665};
1666
1667/* - pool: digest algorithm, hash description and scratch buffer */
1668struct tcp_md5sig_pool {
1669 struct ahash_request *md5_req;
1670 void *scratch;
1671};
1672
1673/* - functions */
1674int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1675 const struct sock *sk, const struct sk_buff *skb);
1676int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1677 int family, u8 prefixlen, int l3index, u8 flags,
1678 const u8 *newkey, u8 newkeylen);
1679int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr,
1680 int family, u8 prefixlen, int l3index,
1681 struct tcp_md5sig_key *key);
1682
1683int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1684 int family, u8 prefixlen, int l3index, u8 flags);
1685struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1686 const struct sock *addr_sk);
1687
1688#ifdef CONFIG_TCP_MD5SIG
1689#include <linux/jump_label.h>
1690extern struct static_key_false_deferred tcp_md5_needed;
1691struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1692 const union tcp_md5_addr *addr,
1693 int family);
1694static inline struct tcp_md5sig_key *
1695tcp_md5_do_lookup(const struct sock *sk, int l3index,
1696 const union tcp_md5_addr *addr, int family)
1697{
1698 if (!static_branch_unlikely(&tcp_md5_needed.key))
1699 return NULL;
1700 return __tcp_md5_do_lookup(sk, l3index, addr, family);
1701}
1702
1703enum skb_drop_reason
1704tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1705 const void *saddr, const void *daddr,
1706 int family, int dif, int sdif);
1707
1708
1709#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1710#else
1711static inline struct tcp_md5sig_key *
1712tcp_md5_do_lookup(const struct sock *sk, int l3index,
1713 const union tcp_md5_addr *addr, int family)
1714{
1715 return NULL;
1716}
1717
1718static inline enum skb_drop_reason
1719tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1720 const void *saddr, const void *daddr,
1721 int family, int dif, int sdif)
1722{
1723 return SKB_NOT_DROPPED_YET;
1724}
1725#define tcp_twsk_md5_key(twsk) NULL
1726#endif
1727
1728bool tcp_alloc_md5sig_pool(void);
1729
1730struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1731static inline void tcp_put_md5sig_pool(void)
1732{
1733 local_bh_enable();
1734}
1735
1736int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1737 unsigned int header_len);
1738int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1739 const struct tcp_md5sig_key *key);
1740
1741/* From tcp_fastopen.c */
1742void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1743 struct tcp_fastopen_cookie *cookie);
1744void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1745 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1746 u16 try_exp);
1747struct tcp_fastopen_request {
1748 /* Fast Open cookie. Size 0 means a cookie request */
1749 struct tcp_fastopen_cookie cookie;
1750 struct msghdr *data; /* data in MSG_FASTOPEN */
1751 size_t size;
1752 int copied; /* queued in tcp_connect() */
1753 struct ubuf_info *uarg;
1754};
1755void tcp_free_fastopen_req(struct tcp_sock *tp);
1756void tcp_fastopen_destroy_cipher(struct sock *sk);
1757void tcp_fastopen_ctx_destroy(struct net *net);
1758int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1759 void *primary_key, void *backup_key);
1760int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1761 u64 *key);
1762void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1763struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1764 struct request_sock *req,
1765 struct tcp_fastopen_cookie *foc,
1766 const struct dst_entry *dst);
1767void tcp_fastopen_init_key_once(struct net *net);
1768bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1769 struct tcp_fastopen_cookie *cookie);
1770bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1771#define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1772#define TCP_FASTOPEN_KEY_MAX 2
1773#define TCP_FASTOPEN_KEY_BUF_LENGTH \
1774 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1775
1776/* Fastopen key context */
1777struct tcp_fastopen_context {
1778 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1779 int num;
1780 struct rcu_head rcu;
1781};
1782
1783void tcp_fastopen_active_disable(struct sock *sk);
1784bool tcp_fastopen_active_should_disable(struct sock *sk);
1785void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1786void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1787
1788/* Caller needs to wrap with rcu_read_(un)lock() */
1789static inline
1790struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1791{
1792 struct tcp_fastopen_context *ctx;
1793
1794 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1795 if (!ctx)
1796 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1797 return ctx;
1798}
1799
1800static inline
1801bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1802 const struct tcp_fastopen_cookie *orig)
1803{
1804 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1805 orig->len == foc->len &&
1806 !memcmp(orig->val, foc->val, foc->len))
1807 return true;
1808 return false;
1809}
1810
1811static inline
1812int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1813{
1814 return ctx->num;
1815}
1816
1817/* Latencies incurred by various limits for a sender. They are
1818 * chronograph-like stats that are mutually exclusive.
1819 */
1820enum tcp_chrono {
1821 TCP_CHRONO_UNSPEC,
1822 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1823 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1824 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1825 __TCP_CHRONO_MAX,
1826};
1827
1828void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1829void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1830
1831/* This helper is needed, because skb->tcp_tsorted_anchor uses
1832 * the same memory storage than skb->destructor/_skb_refdst
1833 */
1834static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1835{
1836 skb->destructor = NULL;
1837 skb->_skb_refdst = 0UL;
1838}
1839
1840#define tcp_skb_tsorted_save(skb) { \
1841 unsigned long _save = skb->_skb_refdst; \
1842 skb->_skb_refdst = 0UL;
1843
1844#define tcp_skb_tsorted_restore(skb) \
1845 skb->_skb_refdst = _save; \
1846}
1847
1848void tcp_write_queue_purge(struct sock *sk);
1849
1850static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1851{
1852 return skb_rb_first(&sk->tcp_rtx_queue);
1853}
1854
1855static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1856{
1857 return skb_rb_last(&sk->tcp_rtx_queue);
1858}
1859
1860static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1861{
1862 return skb_peek_tail(&sk->sk_write_queue);
1863}
1864
1865#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1866 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1867
1868static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1869{
1870 return skb_peek(&sk->sk_write_queue);
1871}
1872
1873static inline bool tcp_skb_is_last(const struct sock *sk,
1874 const struct sk_buff *skb)
1875{
1876 return skb_queue_is_last(&sk->sk_write_queue, skb);
1877}
1878
1879/**
1880 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
1881 * @sk: socket
1882 *
1883 * Since the write queue can have a temporary empty skb in it,
1884 * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
1885 */
1886static inline bool tcp_write_queue_empty(const struct sock *sk)
1887{
1888 const struct tcp_sock *tp = tcp_sk(sk);
1889
1890 return tp->write_seq == tp->snd_nxt;
1891}
1892
1893static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1894{
1895 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1896}
1897
1898static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1899{
1900 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1901}
1902
1903static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1904{
1905 __skb_queue_tail(&sk->sk_write_queue, skb);
1906
1907 /* Queue it, remembering where we must start sending. */
1908 if (sk->sk_write_queue.next == skb)
1909 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1910}
1911
1912/* Insert new before skb on the write queue of sk. */
1913static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1914 struct sk_buff *skb,
1915 struct sock *sk)
1916{
1917 __skb_queue_before(&sk->sk_write_queue, skb, new);
1918}
1919
1920static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1921{
1922 tcp_skb_tsorted_anchor_cleanup(skb);
1923 __skb_unlink(skb, &sk->sk_write_queue);
1924}
1925
1926void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1927
1928static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1929{
1930 tcp_skb_tsorted_anchor_cleanup(skb);
1931 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1932}
1933
1934static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1935{
1936 list_del(&skb->tcp_tsorted_anchor);
1937 tcp_rtx_queue_unlink(skb, sk);
1938 tcp_wmem_free_skb(sk, skb);
1939}
1940
1941static inline void tcp_push_pending_frames(struct sock *sk)
1942{
1943 if (tcp_send_head(sk)) {
1944 struct tcp_sock *tp = tcp_sk(sk);
1945
1946 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1947 }
1948}
1949
1950/* Start sequence of the skb just after the highest skb with SACKed
1951 * bit, valid only if sacked_out > 0 or when the caller has ensured
1952 * validity by itself.
1953 */
1954static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1955{
1956 if (!tp->sacked_out)
1957 return tp->snd_una;
1958
1959 if (tp->highest_sack == NULL)
1960 return tp->snd_nxt;
1961
1962 return TCP_SKB_CB(tp->highest_sack)->seq;
1963}
1964
1965static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1966{
1967 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1968}
1969
1970static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1971{
1972 return tcp_sk(sk)->highest_sack;
1973}
1974
1975static inline void tcp_highest_sack_reset(struct sock *sk)
1976{
1977 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1978}
1979
1980/* Called when old skb is about to be deleted and replaced by new skb */
1981static inline void tcp_highest_sack_replace(struct sock *sk,
1982 struct sk_buff *old,
1983 struct sk_buff *new)
1984{
1985 if (old == tcp_highest_sack(sk))
1986 tcp_sk(sk)->highest_sack = new;
1987}
1988
1989/* This helper checks if socket has IP_TRANSPARENT set */
1990static inline bool inet_sk_transparent(const struct sock *sk)
1991{
1992 switch (sk->sk_state) {
1993 case TCP_TIME_WAIT:
1994 return inet_twsk(sk)->tw_transparent;
1995 case TCP_NEW_SYN_RECV:
1996 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1997 }
1998 return inet_sk(sk)->transparent;
1999}
2000
2001/* Determines whether this is a thin stream (which may suffer from
2002 * increased latency). Used to trigger latency-reducing mechanisms.
2003 */
2004static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
2005{
2006 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
2007}
2008
2009/* /proc */
2010enum tcp_seq_states {
2011 TCP_SEQ_STATE_LISTENING,
2012 TCP_SEQ_STATE_ESTABLISHED,
2013};
2014
2015void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
2016void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
2017void tcp_seq_stop(struct seq_file *seq, void *v);
2018
2019struct tcp_seq_afinfo {
2020 sa_family_t family;
2021};
2022
2023struct tcp_iter_state {
2024 struct seq_net_private p;
2025 enum tcp_seq_states state;
2026 struct sock *syn_wait_sk;
2027 int bucket, offset, sbucket, num;
2028 loff_t last_pos;
2029};
2030
2031extern struct request_sock_ops tcp_request_sock_ops;
2032extern struct request_sock_ops tcp6_request_sock_ops;
2033
2034void tcp_v4_destroy_sock(struct sock *sk);
2035
2036struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
2037 netdev_features_t features);
2038struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
2039INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
2040INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
2041INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
2042INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
2043int tcp_gro_complete(struct sk_buff *skb);
2044
2045void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
2046
2047static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
2048{
2049 struct net *net = sock_net((struct sock *)tp);
2050 return tp->notsent_lowat ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);
2051}
2052
2053bool tcp_stream_memory_free(const struct sock *sk, int wake);
2054
2055#ifdef CONFIG_PROC_FS
2056int tcp4_proc_init(void);
2057void tcp4_proc_exit(void);
2058#endif
2059
2060int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
2061int tcp_conn_request(struct request_sock_ops *rsk_ops,
2062 const struct tcp_request_sock_ops *af_ops,
2063 struct sock *sk, struct sk_buff *skb);
2064
2065/* TCP af-specific functions */
2066struct tcp_sock_af_ops {
2067#ifdef CONFIG_TCP_MD5SIG
2068 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
2069 const struct sock *addr_sk);
2070 int (*calc_md5_hash)(char *location,
2071 const struct tcp_md5sig_key *md5,
2072 const struct sock *sk,
2073 const struct sk_buff *skb);
2074 int (*md5_parse)(struct sock *sk,
2075 int optname,
2076 sockptr_t optval,
2077 int optlen);
2078#endif
2079};
2080
2081struct tcp_request_sock_ops {
2082 u16 mss_clamp;
2083#ifdef CONFIG_TCP_MD5SIG
2084 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2085 const struct sock *addr_sk);
2086 int (*calc_md5_hash) (char *location,
2087 const struct tcp_md5sig_key *md5,
2088 const struct sock *sk,
2089 const struct sk_buff *skb);
2090#endif
2091#ifdef CONFIG_SYN_COOKIES
2092 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
2093 __u16 *mss);
2094#endif
2095 struct dst_entry *(*route_req)(const struct sock *sk,
2096 struct sk_buff *skb,
2097 struct flowi *fl,
2098 struct request_sock *req);
2099 u32 (*init_seq)(const struct sk_buff *skb);
2100 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2101 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2102 struct flowi *fl, struct request_sock *req,
2103 struct tcp_fastopen_cookie *foc,
2104 enum tcp_synack_type synack_type,
2105 struct sk_buff *syn_skb);
2106};
2107
2108extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2109#if IS_ENABLED(CONFIG_IPV6)
2110extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2111#endif
2112
2113#ifdef CONFIG_SYN_COOKIES
2114static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2115 const struct sock *sk, struct sk_buff *skb,
2116 __u16 *mss)
2117{
2118 tcp_synq_overflow(sk);
2119 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2120 return ops->cookie_init_seq(skb, mss);
2121}
2122#else
2123static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2124 const struct sock *sk, struct sk_buff *skb,
2125 __u16 *mss)
2126{
2127 return 0;
2128}
2129#endif
2130
2131int tcpv4_offload_init(void);
2132
2133void tcp_v4_init(void);
2134void tcp_init(void);
2135
2136/* tcp_recovery.c */
2137void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2138void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2139extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2140 u32 reo_wnd);
2141extern bool tcp_rack_mark_lost(struct sock *sk);
2142extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2143 u64 xmit_time);
2144extern void tcp_rack_reo_timeout(struct sock *sk);
2145extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2146
2147/* tcp_plb.c */
2148
2149/*
2150 * Scaling factor for fractions in PLB. For example, tcp_plb_update_state
2151 * expects cong_ratio which represents fraction of traffic that experienced
2152 * congestion over a single RTT. In order to avoid floating point operations,
2153 * this fraction should be mapped to (1 << TCP_PLB_SCALE) and passed in.
2154 */
2155#define TCP_PLB_SCALE 8
2156
2157/* State for PLB (Protective Load Balancing) for a single TCP connection. */
2158struct tcp_plb_state {
2159 u8 consec_cong_rounds:5, /* consecutive congested rounds */
2160 unused:3;
2161 u32 pause_until; /* jiffies32 when PLB can resume rerouting */
2162};
2163
2164static inline void tcp_plb_init(const struct sock *sk,
2165 struct tcp_plb_state *plb)
2166{
2167 plb->consec_cong_rounds = 0;
2168 plb->pause_until = 0;
2169}
2170void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb,
2171 const int cong_ratio);
2172void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb);
2173void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb);
2174
2175/* At how many usecs into the future should the RTO fire? */
2176static inline s64 tcp_rto_delta_us(const struct sock *sk)
2177{
2178 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2179 u32 rto = inet_csk(sk)->icsk_rto;
2180 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2181
2182 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2183}
2184
2185/*
2186 * Save and compile IPv4 options, return a pointer to it
2187 */
2188static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2189 struct sk_buff *skb)
2190{
2191 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2192 struct ip_options_rcu *dopt = NULL;
2193
2194 if (opt->optlen) {
2195 int opt_size = sizeof(*dopt) + opt->optlen;
2196
2197 dopt = kmalloc(opt_size, GFP_ATOMIC);
2198 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2199 kfree(dopt);
2200 dopt = NULL;
2201 }
2202 }
2203 return dopt;
2204}
2205
2206/* locally generated TCP pure ACKs have skb->truesize == 2
2207 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2208 * This is much faster than dissecting the packet to find out.
2209 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2210 */
2211static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2212{
2213 return skb->truesize == 2;
2214}
2215
2216static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2217{
2218 skb->truesize = 2;
2219}
2220
2221static inline int tcp_inq(struct sock *sk)
2222{
2223 struct tcp_sock *tp = tcp_sk(sk);
2224 int answ;
2225
2226 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2227 answ = 0;
2228 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2229 !tp->urg_data ||
2230 before(tp->urg_seq, tp->copied_seq) ||
2231 !before(tp->urg_seq, tp->rcv_nxt)) {
2232
2233 answ = tp->rcv_nxt - tp->copied_seq;
2234
2235 /* Subtract 1, if FIN was received */
2236 if (answ && sock_flag(sk, SOCK_DONE))
2237 answ--;
2238 } else {
2239 answ = tp->urg_seq - tp->copied_seq;
2240 }
2241
2242 return answ;
2243}
2244
2245int tcp_peek_len(struct socket *sock);
2246
2247static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2248{
2249 u16 segs_in;
2250
2251 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2252
2253 /* We update these fields while other threads might
2254 * read them from tcp_get_info()
2255 */
2256 WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in);
2257 if (skb->len > tcp_hdrlen(skb))
2258 WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in);
2259}
2260
2261/*
2262 * TCP listen path runs lockless.
2263 * We forced "struct sock" to be const qualified to make sure
2264 * we don't modify one of its field by mistake.
2265 * Here, we increment sk_drops which is an atomic_t, so we can safely
2266 * make sock writable again.
2267 */
2268static inline void tcp_listendrop(const struct sock *sk)
2269{
2270 atomic_inc(&((struct sock *)sk)->sk_drops);
2271 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2272}
2273
2274enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2275
2276/*
2277 * Interface for adding Upper Level Protocols over TCP
2278 */
2279
2280#define TCP_ULP_NAME_MAX 16
2281#define TCP_ULP_MAX 128
2282#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2283
2284struct tcp_ulp_ops {
2285 struct list_head list;
2286
2287 /* initialize ulp */
2288 int (*init)(struct sock *sk);
2289 /* update ulp */
2290 void (*update)(struct sock *sk, struct proto *p,
2291 void (*write_space)(struct sock *sk));
2292 /* cleanup ulp */
2293 void (*release)(struct sock *sk);
2294 /* diagnostic */
2295 int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2296 size_t (*get_info_size)(const struct sock *sk);
2297 /* clone ulp */
2298 void (*clone)(const struct request_sock *req, struct sock *newsk,
2299 const gfp_t priority);
2300
2301 char name[TCP_ULP_NAME_MAX];
2302 struct module *owner;
2303};
2304int tcp_register_ulp(struct tcp_ulp_ops *type);
2305void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2306int tcp_set_ulp(struct sock *sk, const char *name);
2307void tcp_get_available_ulp(char *buf, size_t len);
2308void tcp_cleanup_ulp(struct sock *sk);
2309void tcp_update_ulp(struct sock *sk, struct proto *p,
2310 void (*write_space)(struct sock *sk));
2311
2312#define MODULE_ALIAS_TCP_ULP(name) \
2313 __MODULE_INFO(alias, alias_userspace, name); \
2314 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2315
2316#ifdef CONFIG_NET_SOCK_MSG
2317struct sk_msg;
2318struct sk_psock;
2319
2320#ifdef CONFIG_BPF_SYSCALL
2321struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
2322int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
2323void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2324#endif /* CONFIG_BPF_SYSCALL */
2325
2326int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
2327 struct sk_msg *msg, u32 bytes, int flags);
2328#endif /* CONFIG_NET_SOCK_MSG */
2329
2330#if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)
2331static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2332{
2333}
2334#endif
2335
2336#ifdef CONFIG_CGROUP_BPF
2337static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2338 struct sk_buff *skb,
2339 unsigned int end_offset)
2340{
2341 skops->skb = skb;
2342 skops->skb_data_end = skb->data + end_offset;
2343}
2344#else
2345static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2346 struct sk_buff *skb,
2347 unsigned int end_offset)
2348{
2349}
2350#endif
2351
2352/* Call BPF_SOCK_OPS program that returns an int. If the return value
2353 * is < 0, then the BPF op failed (for example if the loaded BPF
2354 * program does not support the chosen operation or there is no BPF
2355 * program loaded).
2356 */
2357#ifdef CONFIG_BPF
2358static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2359{
2360 struct bpf_sock_ops_kern sock_ops;
2361 int ret;
2362
2363 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2364 if (sk_fullsock(sk)) {
2365 sock_ops.is_fullsock = 1;
2366 sock_owned_by_me(sk);
2367 }
2368
2369 sock_ops.sk = sk;
2370 sock_ops.op = op;
2371 if (nargs > 0)
2372 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2373
2374 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2375 if (ret == 0)
2376 ret = sock_ops.reply;
2377 else
2378 ret = -1;
2379 return ret;
2380}
2381
2382static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2383{
2384 u32 args[2] = {arg1, arg2};
2385
2386 return tcp_call_bpf(sk, op, 2, args);
2387}
2388
2389static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2390 u32 arg3)
2391{
2392 u32 args[3] = {arg1, arg2, arg3};
2393
2394 return tcp_call_bpf(sk, op, 3, args);
2395}
2396
2397#else
2398static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2399{
2400 return -EPERM;
2401}
2402
2403static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2404{
2405 return -EPERM;
2406}
2407
2408static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2409 u32 arg3)
2410{
2411 return -EPERM;
2412}
2413
2414#endif
2415
2416static inline u32 tcp_timeout_init(struct sock *sk)
2417{
2418 int timeout;
2419
2420 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2421
2422 if (timeout <= 0)
2423 timeout = TCP_TIMEOUT_INIT;
2424 return min_t(int, timeout, TCP_RTO_MAX);
2425}
2426
2427static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2428{
2429 int rwnd;
2430
2431 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2432
2433 if (rwnd < 0)
2434 rwnd = 0;
2435 return rwnd;
2436}
2437
2438static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2439{
2440 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2441}
2442
2443static inline void tcp_bpf_rtt(struct sock *sk)
2444{
2445 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2446 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2447}
2448
2449#if IS_ENABLED(CONFIG_SMC)
2450extern struct static_key_false tcp_have_smc;
2451#endif
2452
2453#if IS_ENABLED(CONFIG_TLS_DEVICE)
2454void clean_acked_data_enable(struct inet_connection_sock *icsk,
2455 void (*cad)(struct sock *sk, u32 ack_seq));
2456void clean_acked_data_disable(struct inet_connection_sock *icsk);
2457void clean_acked_data_flush(void);
2458#endif
2459
2460DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2461static inline void tcp_add_tx_delay(struct sk_buff *skb,
2462 const struct tcp_sock *tp)
2463{
2464 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2465 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2466}
2467
2468/* Compute Earliest Departure Time for some control packets
2469 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2470 */
2471static inline u64 tcp_transmit_time(const struct sock *sk)
2472{
2473 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2474 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2475 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2476
2477 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;
2478 }
2479 return 0;
2480}
2481
2482#endif /* _TCP_H */
1/*
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.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
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.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define FASTRETRANS_DEBUG 1
22
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>
33
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>
39#include <net/sock.h>
40#include <net/snmp.h>
41#include <net/ip.h>
42#include <net/tcp_states.h>
43#include <net/inet_ecn.h>
44#include <net/dst.h>
45
46#include <linux/seq_file.h>
47#include <linux/memcontrol.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER (128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56
57/*
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
60 */
61#define MAX_TCP_WINDOW 32767U
62
63/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
64#define TCP_MIN_MSS 88U
65
66/* The least MTU to use for probing */
67#define TCP_BASE_MSS 1024
68
69/* probing interval, default to 10 minutes as per RFC4821 */
70#define TCP_PROBE_INTERVAL 600
71
72/* Specify interval when tcp mtu probing will stop */
73#define TCP_PROBE_THRESHOLD 8
74
75/* After receiving this amount of duplicate ACKs fast retransmit starts. */
76#define TCP_FASTRETRANS_THRESH 3
77
78/* Maximal number of ACKs sent quickly to accelerate slow-start. */
79#define TCP_MAX_QUICKACKS 16U
80
81/* urg_data states */
82#define TCP_URG_VALID 0x0100
83#define TCP_URG_NOTYET 0x0200
84#define TCP_URG_READ 0x0400
85
86#define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
91 */
92
93#define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
98 */
99
100#define TCP_SYN_RETRIES 6 /* This is how many retries are done
101 * when active opening a connection.
102 * RFC1122 says the minimum retry MUST
103 * be at least 180secs. Nevertheless
104 * this value is corresponding to
105 * 63secs of retransmission with the
106 * current initial RTO.
107 */
108
109#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
110 * when passive opening a connection.
111 * This is corresponding to 31secs of
112 * retransmission with the current
113 * initial RTO.
114 */
115
116#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
117 * state, about 60 seconds */
118#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
119 /* BSD style FIN_WAIT2 deadlock breaker.
120 * It used to be 3min, new value is 60sec,
121 * to combine FIN-WAIT-2 timeout with
122 * TIME-WAIT timer.
123 */
124
125#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
126#if HZ >= 100
127#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
128#define TCP_ATO_MIN ((unsigned)(HZ/25))
129#else
130#define TCP_DELACK_MIN 4U
131#define TCP_ATO_MIN 4U
132#endif
133#define TCP_RTO_MAX ((unsigned)(120*HZ))
134#define TCP_RTO_MIN ((unsigned)(HZ/5))
135#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
136#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
137 * used as a fallback RTO for the
138 * initial data transmission if no
139 * valid RTT sample has been acquired,
140 * most likely due to retrans in 3WHS.
141 */
142
143#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
144 * for local resources.
145 */
146
147#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
148#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
149#define TCP_KEEPALIVE_INTVL (75*HZ)
150
151#define MAX_TCP_KEEPIDLE 32767
152#define MAX_TCP_KEEPINTVL 32767
153#define MAX_TCP_KEEPCNT 127
154#define MAX_TCP_SYNCNT 127
155
156#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
157
158#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
159#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
160 * after this time. It should be equal
161 * (or greater than) TCP_TIMEWAIT_LEN
162 * to provide reliability equal to one
163 * provided by timewait state.
164 */
165#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
166 * timestamps. It must be less than
167 * minimal timewait lifetime.
168 */
169/*
170 * TCP option
171 */
172
173#define TCPOPT_NOP 1 /* Padding */
174#define TCPOPT_EOL 0 /* End of options */
175#define TCPOPT_MSS 2 /* Segment size negotiating */
176#define TCPOPT_WINDOW 3 /* Window scaling */
177#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
178#define TCPOPT_SACK 5 /* SACK Block */
179#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
180#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
181#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
182#define TCPOPT_EXP 254 /* Experimental */
183/* Magic number to be after the option value for sharing TCP
184 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
185 */
186#define TCPOPT_FASTOPEN_MAGIC 0xF989
187
188/*
189 * TCP option lengths
190 */
191
192#define TCPOLEN_MSS 4
193#define TCPOLEN_WINDOW 3
194#define TCPOLEN_SACK_PERM 2
195#define TCPOLEN_TIMESTAMP 10
196#define TCPOLEN_MD5SIG 18
197#define TCPOLEN_FASTOPEN_BASE 2
198#define TCPOLEN_EXP_FASTOPEN_BASE 4
199
200/* But this is what stacks really send out. */
201#define TCPOLEN_TSTAMP_ALIGNED 12
202#define TCPOLEN_WSCALE_ALIGNED 4
203#define TCPOLEN_SACKPERM_ALIGNED 4
204#define TCPOLEN_SACK_BASE 2
205#define TCPOLEN_SACK_BASE_ALIGNED 4
206#define TCPOLEN_SACK_PERBLOCK 8
207#define TCPOLEN_MD5SIG_ALIGNED 20
208#define TCPOLEN_MSS_ALIGNED 4
209
210/* Flags in tp->nonagle */
211#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
212#define TCP_NAGLE_CORK 2 /* Socket is corked */
213#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
214
215/* TCP thin-stream limits */
216#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
217
218/* TCP initial congestion window as per rfc6928 */
219#define TCP_INIT_CWND 10
220
221/* Bit Flags for sysctl_tcp_fastopen */
222#define TFO_CLIENT_ENABLE 1
223#define TFO_SERVER_ENABLE 2
224#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
225
226/* Accept SYN data w/o any cookie option */
227#define TFO_SERVER_COOKIE_NOT_REQD 0x200
228
229/* Force enable TFO on all listeners, i.e., not requiring the
230 * TCP_FASTOPEN socket option.
231 */
232#define TFO_SERVER_WO_SOCKOPT1 0x400
233
234extern struct inet_timewait_death_row tcp_death_row;
235
236/* sysctl variables for tcp */
237extern int sysctl_tcp_timestamps;
238extern int sysctl_tcp_window_scaling;
239extern int sysctl_tcp_sack;
240extern int sysctl_tcp_fastopen;
241extern int sysctl_tcp_retrans_collapse;
242extern int sysctl_tcp_stdurg;
243extern int sysctl_tcp_rfc1337;
244extern int sysctl_tcp_abort_on_overflow;
245extern int sysctl_tcp_max_orphans;
246extern int sysctl_tcp_fack;
247extern int sysctl_tcp_reordering;
248extern int sysctl_tcp_max_reordering;
249extern int sysctl_tcp_dsack;
250extern long sysctl_tcp_mem[3];
251extern int sysctl_tcp_wmem[3];
252extern int sysctl_tcp_rmem[3];
253extern int sysctl_tcp_app_win;
254extern int sysctl_tcp_adv_win_scale;
255extern int sysctl_tcp_frto;
256extern int sysctl_tcp_low_latency;
257extern int sysctl_tcp_nometrics_save;
258extern int sysctl_tcp_moderate_rcvbuf;
259extern int sysctl_tcp_tso_win_divisor;
260extern int sysctl_tcp_workaround_signed_windows;
261extern int sysctl_tcp_slow_start_after_idle;
262extern int sysctl_tcp_thin_linear_timeouts;
263extern int sysctl_tcp_thin_dupack;
264extern int sysctl_tcp_early_retrans;
265extern int sysctl_tcp_limit_output_bytes;
266extern int sysctl_tcp_challenge_ack_limit;
267extern int sysctl_tcp_min_tso_segs;
268extern int sysctl_tcp_min_rtt_wlen;
269extern int sysctl_tcp_autocorking;
270extern int sysctl_tcp_invalid_ratelimit;
271extern int sysctl_tcp_pacing_ss_ratio;
272extern int sysctl_tcp_pacing_ca_ratio;
273
274extern atomic_long_t tcp_memory_allocated;
275extern struct percpu_counter tcp_sockets_allocated;
276extern int tcp_memory_pressure;
277
278/* optimized version of sk_under_memory_pressure() for TCP sockets */
279static inline bool tcp_under_memory_pressure(const struct sock *sk)
280{
281 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
282 mem_cgroup_under_socket_pressure(sk->sk_memcg))
283 return true;
284
285 return tcp_memory_pressure;
286}
287/*
288 * The next routines deal with comparing 32 bit unsigned ints
289 * and worry about wraparound (automatic with unsigned arithmetic).
290 */
291
292static inline bool before(__u32 seq1, __u32 seq2)
293{
294 return (__s32)(seq1-seq2) < 0;
295}
296#define after(seq2, seq1) before(seq1, seq2)
297
298/* is s2<=s1<=s3 ? */
299static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
300{
301 return seq3 - seq2 >= seq1 - seq2;
302}
303
304static inline bool tcp_out_of_memory(struct sock *sk)
305{
306 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
307 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
308 return true;
309 return false;
310}
311
312void sk_forced_mem_schedule(struct sock *sk, int size);
313
314static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
315{
316 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
317 int orphans = percpu_counter_read_positive(ocp);
318
319 if (orphans << shift > sysctl_tcp_max_orphans) {
320 orphans = percpu_counter_sum_positive(ocp);
321 if (orphans << shift > sysctl_tcp_max_orphans)
322 return true;
323 }
324 return false;
325}
326
327bool tcp_check_oom(struct sock *sk, int shift);
328
329
330extern struct proto tcp_prot;
331
332#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
333#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
334#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
335#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
336
337void tcp_tasklet_init(void);
338
339void tcp_v4_err(struct sk_buff *skb, u32);
340
341void tcp_shutdown(struct sock *sk, int how);
342
343void tcp_v4_early_demux(struct sk_buff *skb);
344int tcp_v4_rcv(struct sk_buff *skb);
345
346int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
347int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
348int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
349 int flags);
350void tcp_release_cb(struct sock *sk);
351void tcp_wfree(struct sk_buff *skb);
352void tcp_write_timer_handler(struct sock *sk);
353void tcp_delack_timer_handler(struct sock *sk);
354int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
355int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
356void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
357 const struct tcphdr *th, unsigned int len);
358void tcp_rcv_space_adjust(struct sock *sk);
359int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
360void tcp_twsk_destructor(struct sock *sk);
361ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
362 struct pipe_inode_info *pipe, size_t len,
363 unsigned int flags);
364
365static inline void tcp_dec_quickack_mode(struct sock *sk,
366 const unsigned int pkts)
367{
368 struct inet_connection_sock *icsk = inet_csk(sk);
369
370 if (icsk->icsk_ack.quick) {
371 if (pkts >= icsk->icsk_ack.quick) {
372 icsk->icsk_ack.quick = 0;
373 /* Leaving quickack mode we deflate ATO. */
374 icsk->icsk_ack.ato = TCP_ATO_MIN;
375 } else
376 icsk->icsk_ack.quick -= pkts;
377 }
378}
379
380#define TCP_ECN_OK 1
381#define TCP_ECN_QUEUE_CWR 2
382#define TCP_ECN_DEMAND_CWR 4
383#define TCP_ECN_SEEN 8
384
385enum tcp_tw_status {
386 TCP_TW_SUCCESS = 0,
387 TCP_TW_RST = 1,
388 TCP_TW_ACK = 2,
389 TCP_TW_SYN = 3
390};
391
392
393enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
394 struct sk_buff *skb,
395 const struct tcphdr *th);
396struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
397 struct request_sock *req, bool fastopen);
398int tcp_child_process(struct sock *parent, struct sock *child,
399 struct sk_buff *skb);
400void tcp_enter_loss(struct sock *sk);
401void tcp_clear_retrans(struct tcp_sock *tp);
402void tcp_update_metrics(struct sock *sk);
403void tcp_init_metrics(struct sock *sk);
404void tcp_metrics_init(void);
405bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
406 bool paws_check, bool timestamps);
407bool tcp_remember_stamp(struct sock *sk);
408bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
409void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
410void tcp_disable_fack(struct tcp_sock *tp);
411void tcp_close(struct sock *sk, long timeout);
412void tcp_init_sock(struct sock *sk);
413unsigned int tcp_poll(struct file *file, struct socket *sock,
414 struct poll_table_struct *wait);
415int tcp_getsockopt(struct sock *sk, int level, int optname,
416 char __user *optval, int __user *optlen);
417int tcp_setsockopt(struct sock *sk, int level, int optname,
418 char __user *optval, unsigned int optlen);
419int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
420 char __user *optval, int __user *optlen);
421int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
422 char __user *optval, unsigned int optlen);
423void tcp_set_keepalive(struct sock *sk, int val);
424void tcp_syn_ack_timeout(const struct request_sock *req);
425int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
426 int flags, int *addr_len);
427void tcp_parse_options(const struct sk_buff *skb,
428 struct tcp_options_received *opt_rx,
429 int estab, struct tcp_fastopen_cookie *foc);
430const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
431
432/*
433 * TCP v4 functions exported for the inet6 API
434 */
435
436void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
437void tcp_v4_mtu_reduced(struct sock *sk);
438void tcp_req_err(struct sock *sk, u32 seq, bool abort);
439int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
440struct sock *tcp_create_openreq_child(const struct sock *sk,
441 struct request_sock *req,
442 struct sk_buff *skb);
443void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
444struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
445 struct request_sock *req,
446 struct dst_entry *dst,
447 struct request_sock *req_unhash,
448 bool *own_req);
449int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
450int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
451int tcp_connect(struct sock *sk);
452enum tcp_synack_type {
453 TCP_SYNACK_NORMAL,
454 TCP_SYNACK_FASTOPEN,
455 TCP_SYNACK_COOKIE,
456};
457struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
458 struct request_sock *req,
459 struct tcp_fastopen_cookie *foc,
460 enum tcp_synack_type synack_type);
461int tcp_disconnect(struct sock *sk, int flags);
462
463void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
464int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
465void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
466
467/* From syncookies.c */
468struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
469 struct request_sock *req,
470 struct dst_entry *dst);
471int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
472 u32 cookie);
473struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
474#ifdef CONFIG_SYN_COOKIES
475
476/* Syncookies use a monotonic timer which increments every 60 seconds.
477 * This counter is used both as a hash input and partially encoded into
478 * the cookie value. A cookie is only validated further if the delta
479 * between the current counter value and the encoded one is less than this,
480 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
481 * the counter advances immediately after a cookie is generated).
482 */
483#define MAX_SYNCOOKIE_AGE 2
484#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
485#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
486
487/* syncookies: remember time of last synqueue overflow
488 * But do not dirty this field too often (once per second is enough)
489 * It is racy as we do not hold a lock, but race is very minor.
490 */
491static inline void tcp_synq_overflow(const struct sock *sk)
492{
493 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
494 unsigned long now = jiffies;
495
496 if (time_after(now, last_overflow + HZ))
497 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
498}
499
500/* syncookies: no recent synqueue overflow on this listening socket? */
501static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
502{
503 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
504
505 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
506}
507
508static inline u32 tcp_cookie_time(void)
509{
510 u64 val = get_jiffies_64();
511
512 do_div(val, TCP_SYNCOOKIE_PERIOD);
513 return val;
514}
515
516u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
517 u16 *mssp);
518__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
519__u32 cookie_init_timestamp(struct request_sock *req);
520bool cookie_timestamp_decode(struct tcp_options_received *opt);
521bool cookie_ecn_ok(const struct tcp_options_received *opt,
522 const struct net *net, const struct dst_entry *dst);
523
524/* From net/ipv6/syncookies.c */
525int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
526 u32 cookie);
527struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
528
529u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
530 const struct tcphdr *th, u16 *mssp);
531__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
532#endif
533/* tcp_output.c */
534
535u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
536 int min_tso_segs);
537void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
538 int nonagle);
539bool tcp_may_send_now(struct sock *sk);
540int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
541int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
542void tcp_retransmit_timer(struct sock *sk);
543void tcp_xmit_retransmit_queue(struct sock *);
544void tcp_simple_retransmit(struct sock *);
545int tcp_trim_head(struct sock *, struct sk_buff *, u32);
546int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
547
548void tcp_send_probe0(struct sock *);
549void tcp_send_partial(struct sock *);
550int tcp_write_wakeup(struct sock *, int mib);
551void tcp_send_fin(struct sock *sk);
552void tcp_send_active_reset(struct sock *sk, gfp_t priority);
553int tcp_send_synack(struct sock *);
554void tcp_push_one(struct sock *, unsigned int mss_now);
555void tcp_send_ack(struct sock *sk);
556void tcp_send_delayed_ack(struct sock *sk);
557void tcp_send_loss_probe(struct sock *sk);
558bool tcp_schedule_loss_probe(struct sock *sk);
559void tcp_skb_collapse_tstamp(struct sk_buff *skb,
560 const struct sk_buff *next_skb);
561
562/* tcp_input.c */
563void tcp_resume_early_retransmit(struct sock *sk);
564void tcp_rearm_rto(struct sock *sk);
565void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
566void tcp_reset(struct sock *sk);
567void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
568void tcp_fin(struct sock *sk);
569
570/* tcp_timer.c */
571void tcp_init_xmit_timers(struct sock *);
572static inline void tcp_clear_xmit_timers(struct sock *sk)
573{
574 inet_csk_clear_xmit_timers(sk);
575}
576
577unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
578unsigned int tcp_current_mss(struct sock *sk);
579
580/* Bound MSS / TSO packet size with the half of the window */
581static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
582{
583 int cutoff;
584
585 /* When peer uses tiny windows, there is no use in packetizing
586 * to sub-MSS pieces for the sake of SWS or making sure there
587 * are enough packets in the pipe for fast recovery.
588 *
589 * On the other hand, for extremely large MSS devices, handling
590 * smaller than MSS windows in this way does make sense.
591 */
592 if (tp->max_window > TCP_MSS_DEFAULT)
593 cutoff = (tp->max_window >> 1);
594 else
595 cutoff = tp->max_window;
596
597 if (cutoff && pktsize > cutoff)
598 return max_t(int, cutoff, 68U - tp->tcp_header_len);
599 else
600 return pktsize;
601}
602
603/* tcp.c */
604void tcp_get_info(struct sock *, struct tcp_info *);
605
606/* Read 'sendfile()'-style from a TCP socket */
607int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
608 sk_read_actor_t recv_actor);
609
610void tcp_initialize_rcv_mss(struct sock *sk);
611
612int tcp_mtu_to_mss(struct sock *sk, int pmtu);
613int tcp_mss_to_mtu(struct sock *sk, int mss);
614void tcp_mtup_init(struct sock *sk);
615void tcp_init_buffer_space(struct sock *sk);
616
617static inline void tcp_bound_rto(const struct sock *sk)
618{
619 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
620 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
621}
622
623static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
624{
625 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
626}
627
628static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
629{
630 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
631 ntohl(TCP_FLAG_ACK) |
632 snd_wnd);
633}
634
635static inline void tcp_fast_path_on(struct tcp_sock *tp)
636{
637 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
638}
639
640static inline void tcp_fast_path_check(struct sock *sk)
641{
642 struct tcp_sock *tp = tcp_sk(sk);
643
644 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
645 tp->rcv_wnd &&
646 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
647 !tp->urg_data)
648 tcp_fast_path_on(tp);
649}
650
651/* Compute the actual rto_min value */
652static inline u32 tcp_rto_min(struct sock *sk)
653{
654 const struct dst_entry *dst = __sk_dst_get(sk);
655 u32 rto_min = TCP_RTO_MIN;
656
657 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
658 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
659 return rto_min;
660}
661
662static inline u32 tcp_rto_min_us(struct sock *sk)
663{
664 return jiffies_to_usecs(tcp_rto_min(sk));
665}
666
667static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
668{
669 return dst_metric_locked(dst, RTAX_CC_ALGO);
670}
671
672/* Minimum RTT in usec. ~0 means not available. */
673static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
674{
675 return minmax_get(&tp->rtt_min);
676}
677
678/* Compute the actual receive window we are currently advertising.
679 * Rcv_nxt can be after the window if our peer push more data
680 * than the offered window.
681 */
682static inline u32 tcp_receive_window(const struct tcp_sock *tp)
683{
684 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
685
686 if (win < 0)
687 win = 0;
688 return (u32) win;
689}
690
691/* Choose a new window, without checks for shrinking, and without
692 * scaling applied to the result. The caller does these things
693 * if necessary. This is a "raw" window selection.
694 */
695u32 __tcp_select_window(struct sock *sk);
696
697void tcp_send_window_probe(struct sock *sk);
698
699/* TCP timestamps are only 32-bits, this causes a slight
700 * complication on 64-bit systems since we store a snapshot
701 * of jiffies in the buffer control blocks below. We decided
702 * to use only the low 32-bits of jiffies and hide the ugly
703 * casts with the following macro.
704 */
705#define tcp_time_stamp ((__u32)(jiffies))
706
707static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
708{
709 return skb->skb_mstamp.stamp_jiffies;
710}
711
712
713#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
714
715#define TCPHDR_FIN 0x01
716#define TCPHDR_SYN 0x02
717#define TCPHDR_RST 0x04
718#define TCPHDR_PSH 0x08
719#define TCPHDR_ACK 0x10
720#define TCPHDR_URG 0x20
721#define TCPHDR_ECE 0x40
722#define TCPHDR_CWR 0x80
723
724#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
725
726/* This is what the send packet queuing engine uses to pass
727 * TCP per-packet control information to the transmission code.
728 * We also store the host-order sequence numbers in here too.
729 * This is 44 bytes if IPV6 is enabled.
730 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
731 */
732struct tcp_skb_cb {
733 __u32 seq; /* Starting sequence number */
734 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
735 union {
736 /* Note : tcp_tw_isn is used in input path only
737 * (isn chosen by tcp_timewait_state_process())
738 *
739 * tcp_gso_segs/size are used in write queue only,
740 * cf tcp_skb_pcount()/tcp_skb_mss()
741 */
742 __u32 tcp_tw_isn;
743 struct {
744 u16 tcp_gso_segs;
745 u16 tcp_gso_size;
746 };
747 };
748 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
749
750 __u8 sacked; /* State flags for SACK/FACK. */
751#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
752#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
753#define TCPCB_LOST 0x04 /* SKB is lost */
754#define TCPCB_TAGBITS 0x07 /* All tag bits */
755#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
756#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
757#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
758 TCPCB_REPAIRED)
759
760 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
761 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
762 eor:1, /* Is skb MSG_EOR marked? */
763 unused:6;
764 __u32 ack_seq; /* Sequence number ACK'd */
765 union {
766 struct {
767 /* There is space for up to 24 bytes */
768 __u32 in_flight:30,/* Bytes in flight at transmit */
769 is_app_limited:1, /* cwnd not fully used? */
770 unused:1;
771 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
772 __u32 delivered;
773 /* start of send pipeline phase */
774 struct skb_mstamp first_tx_mstamp;
775 /* when we reached the "delivered" count */
776 struct skb_mstamp delivered_mstamp;
777 } tx; /* only used for outgoing skbs */
778 union {
779 struct inet_skb_parm h4;
780#if IS_ENABLED(CONFIG_IPV6)
781 struct inet6_skb_parm h6;
782#endif
783 } header; /* For incoming skbs */
784 };
785};
786
787#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
788
789
790#if IS_ENABLED(CONFIG_IPV6)
791/* This is the variant of inet6_iif() that must be used by TCP,
792 * as TCP moves IP6CB into a different location in skb->cb[]
793 */
794static inline int tcp_v6_iif(const struct sk_buff *skb)
795{
796 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
797
798 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
799}
800#endif
801
802/* TCP_SKB_CB reference means this can not be used from early demux */
803static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
804{
805#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
806 if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
807 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
808 return true;
809#endif
810 return false;
811}
812
813/* Due to TSO, an SKB can be composed of multiple actual
814 * packets. To keep these tracked properly, we use this.
815 */
816static inline int tcp_skb_pcount(const struct sk_buff *skb)
817{
818 return TCP_SKB_CB(skb)->tcp_gso_segs;
819}
820
821static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
822{
823 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
824}
825
826static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
827{
828 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
829}
830
831/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
832static inline int tcp_skb_mss(const struct sk_buff *skb)
833{
834 return TCP_SKB_CB(skb)->tcp_gso_size;
835}
836
837static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
838{
839 return likely(!TCP_SKB_CB(skb)->eor);
840}
841
842/* Events passed to congestion control interface */
843enum tcp_ca_event {
844 CA_EVENT_TX_START, /* first transmit when no packets in flight */
845 CA_EVENT_CWND_RESTART, /* congestion window restart */
846 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
847 CA_EVENT_LOSS, /* loss timeout */
848 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
849 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
850 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
851 CA_EVENT_NON_DELAYED_ACK,
852};
853
854/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
855enum tcp_ca_ack_event_flags {
856 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
857 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
858 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
859};
860
861/*
862 * Interface for adding new TCP congestion control handlers
863 */
864#define TCP_CA_NAME_MAX 16
865#define TCP_CA_MAX 128
866#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
867
868#define TCP_CA_UNSPEC 0
869
870/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
871#define TCP_CONG_NON_RESTRICTED 0x1
872/* Requires ECN/ECT set on all packets */
873#define TCP_CONG_NEEDS_ECN 0x2
874
875union tcp_cc_info;
876
877struct ack_sample {
878 u32 pkts_acked;
879 s32 rtt_us;
880 u32 in_flight;
881};
882
883/* A rate sample measures the number of (original/retransmitted) data
884 * packets delivered "delivered" over an interval of time "interval_us".
885 * The tcp_rate.c code fills in the rate sample, and congestion
886 * control modules that define a cong_control function to run at the end
887 * of ACK processing can optionally chose to consult this sample when
888 * setting cwnd and pacing rate.
889 * A sample is invalid if "delivered" or "interval_us" is negative.
890 */
891struct rate_sample {
892 struct skb_mstamp prior_mstamp; /* starting timestamp for interval */
893 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
894 s32 delivered; /* number of packets delivered over interval */
895 long interval_us; /* time for tp->delivered to incr "delivered" */
896 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
897 int losses; /* number of packets marked lost upon ACK */
898 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
899 u32 prior_in_flight; /* in flight before this ACK */
900 bool is_app_limited; /* is sample from packet with bubble in pipe? */
901 bool is_retrans; /* is sample from retransmission? */
902};
903
904struct tcp_congestion_ops {
905 struct list_head list;
906 u32 key;
907 u32 flags;
908
909 /* initialize private data (optional) */
910 void (*init)(struct sock *sk);
911 /* cleanup private data (optional) */
912 void (*release)(struct sock *sk);
913
914 /* return slow start threshold (required) */
915 u32 (*ssthresh)(struct sock *sk);
916 /* do new cwnd calculation (required) */
917 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
918 /* call before changing ca_state (optional) */
919 void (*set_state)(struct sock *sk, u8 new_state);
920 /* call when cwnd event occurs (optional) */
921 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
922 /* call when ack arrives (optional) */
923 void (*in_ack_event)(struct sock *sk, u32 flags);
924 /* new value of cwnd after loss (optional) */
925 u32 (*undo_cwnd)(struct sock *sk);
926 /* hook for packet ack accounting (optional) */
927 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
928 /* suggest number of segments for each skb to transmit (optional) */
929 u32 (*tso_segs_goal)(struct sock *sk);
930 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
931 u32 (*sndbuf_expand)(struct sock *sk);
932 /* call when packets are delivered to update cwnd and pacing rate,
933 * after all the ca_state processing. (optional)
934 */
935 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
936 /* get info for inet_diag (optional) */
937 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
938 union tcp_cc_info *info);
939
940 char name[TCP_CA_NAME_MAX];
941 struct module *owner;
942};
943
944int tcp_register_congestion_control(struct tcp_congestion_ops *type);
945void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
946
947void tcp_assign_congestion_control(struct sock *sk);
948void tcp_init_congestion_control(struct sock *sk);
949void tcp_cleanup_congestion_control(struct sock *sk);
950int tcp_set_default_congestion_control(const char *name);
951void tcp_get_default_congestion_control(char *name);
952void tcp_get_available_congestion_control(char *buf, size_t len);
953void tcp_get_allowed_congestion_control(char *buf, size_t len);
954int tcp_set_allowed_congestion_control(char *allowed);
955int tcp_set_congestion_control(struct sock *sk, const char *name);
956u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
957void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
958
959u32 tcp_reno_ssthresh(struct sock *sk);
960u32 tcp_reno_undo_cwnd(struct sock *sk);
961void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
962extern struct tcp_congestion_ops tcp_reno;
963
964struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
965u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
966#ifdef CONFIG_INET
967char *tcp_ca_get_name_by_key(u32 key, char *buffer);
968#else
969static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
970{
971 return NULL;
972}
973#endif
974
975static inline bool tcp_ca_needs_ecn(const struct sock *sk)
976{
977 const struct inet_connection_sock *icsk = inet_csk(sk);
978
979 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
980}
981
982static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
983{
984 struct inet_connection_sock *icsk = inet_csk(sk);
985
986 if (icsk->icsk_ca_ops->set_state)
987 icsk->icsk_ca_ops->set_state(sk, ca_state);
988 icsk->icsk_ca_state = ca_state;
989}
990
991static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
992{
993 const struct inet_connection_sock *icsk = inet_csk(sk);
994
995 if (icsk->icsk_ca_ops->cwnd_event)
996 icsk->icsk_ca_ops->cwnd_event(sk, event);
997}
998
999/* From tcp_rate.c */
1000void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1001void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1002 struct rate_sample *rs);
1003void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1004 struct skb_mstamp *now, struct rate_sample *rs);
1005void tcp_rate_check_app_limited(struct sock *sk);
1006
1007/* These functions determine how the current flow behaves in respect of SACK
1008 * handling. SACK is negotiated with the peer, and therefore it can vary
1009 * between different flows.
1010 *
1011 * tcp_is_sack - SACK enabled
1012 * tcp_is_reno - No SACK
1013 * tcp_is_fack - FACK enabled, implies SACK enabled
1014 */
1015static inline int tcp_is_sack(const struct tcp_sock *tp)
1016{
1017 return tp->rx_opt.sack_ok;
1018}
1019
1020static inline bool tcp_is_reno(const struct tcp_sock *tp)
1021{
1022 return !tcp_is_sack(tp);
1023}
1024
1025static inline bool tcp_is_fack(const struct tcp_sock *tp)
1026{
1027 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
1028}
1029
1030static inline void tcp_enable_fack(struct tcp_sock *tp)
1031{
1032 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
1033}
1034
1035/* TCP early-retransmit (ER) is similar to but more conservative than
1036 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
1037 */
1038static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
1039{
1040 struct net *net = sock_net((struct sock *)tp);
1041
1042 tp->do_early_retrans = sysctl_tcp_early_retrans &&
1043 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
1044 net->ipv4.sysctl_tcp_reordering == 3;
1045}
1046
1047static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
1048{
1049 tp->do_early_retrans = 0;
1050}
1051
1052static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1053{
1054 return tp->sacked_out + tp->lost_out;
1055}
1056
1057/* This determines how many packets are "in the network" to the best
1058 * of our knowledge. In many cases it is conservative, but where
1059 * detailed information is available from the receiver (via SACK
1060 * blocks etc.) we can make more aggressive calculations.
1061 *
1062 * Use this for decisions involving congestion control, use just
1063 * tp->packets_out to determine if the send queue is empty or not.
1064 *
1065 * Read this equation as:
1066 *
1067 * "Packets sent once on transmission queue" MINUS
1068 * "Packets left network, but not honestly ACKed yet" PLUS
1069 * "Packets fast retransmitted"
1070 */
1071static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1072{
1073 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1074}
1075
1076#define TCP_INFINITE_SSTHRESH 0x7fffffff
1077
1078static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1079{
1080 return tp->snd_cwnd < tp->snd_ssthresh;
1081}
1082
1083static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1084{
1085 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1086}
1087
1088static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1089{
1090 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1091 (1 << inet_csk(sk)->icsk_ca_state);
1092}
1093
1094/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1095 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1096 * ssthresh.
1097 */
1098static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1099{
1100 const struct tcp_sock *tp = tcp_sk(sk);
1101
1102 if (tcp_in_cwnd_reduction(sk))
1103 return tp->snd_ssthresh;
1104 else
1105 return max(tp->snd_ssthresh,
1106 ((tp->snd_cwnd >> 1) +
1107 (tp->snd_cwnd >> 2)));
1108}
1109
1110/* Use define here intentionally to get WARN_ON location shown at the caller */
1111#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1112
1113void tcp_enter_cwr(struct sock *sk);
1114__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1115
1116/* The maximum number of MSS of available cwnd for which TSO defers
1117 * sending if not using sysctl_tcp_tso_win_divisor.
1118 */
1119static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1120{
1121 return 3;
1122}
1123
1124/* Returns end sequence number of the receiver's advertised window */
1125static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1126{
1127 return tp->snd_una + tp->snd_wnd;
1128}
1129
1130/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1131 * flexible approach. The RFC suggests cwnd should not be raised unless
1132 * it was fully used previously. And that's exactly what we do in
1133 * congestion avoidance mode. But in slow start we allow cwnd to grow
1134 * as long as the application has used half the cwnd.
1135 * Example :
1136 * cwnd is 10 (IW10), but application sends 9 frames.
1137 * We allow cwnd to reach 18 when all frames are ACKed.
1138 * This check is safe because it's as aggressive as slow start which already
1139 * risks 100% overshoot. The advantage is that we discourage application to
1140 * either send more filler packets or data to artificially blow up the cwnd
1141 * usage, and allow application-limited process to probe bw more aggressively.
1142 */
1143static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1144{
1145 const struct tcp_sock *tp = tcp_sk(sk);
1146
1147 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1148 if (tcp_in_slow_start(tp))
1149 return tp->snd_cwnd < 2 * tp->max_packets_out;
1150
1151 return tp->is_cwnd_limited;
1152}
1153
1154/* Something is really bad, we could not queue an additional packet,
1155 * because qdisc is full or receiver sent a 0 window.
1156 * We do not want to add fuel to the fire, or abort too early,
1157 * so make sure the timer we arm now is at least 200ms in the future,
1158 * regardless of current icsk_rto value (as it could be ~2ms)
1159 */
1160static inline unsigned long tcp_probe0_base(const struct sock *sk)
1161{
1162 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1163}
1164
1165/* Variant of inet_csk_rto_backoff() used for zero window probes */
1166static inline unsigned long tcp_probe0_when(const struct sock *sk,
1167 unsigned long max_when)
1168{
1169 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1170
1171 return (unsigned long)min_t(u64, when, max_when);
1172}
1173
1174static inline void tcp_check_probe_timer(struct sock *sk)
1175{
1176 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1177 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1178 tcp_probe0_base(sk), TCP_RTO_MAX);
1179}
1180
1181static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1182{
1183 tp->snd_wl1 = seq;
1184}
1185
1186static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1187{
1188 tp->snd_wl1 = seq;
1189}
1190
1191/*
1192 * Calculate(/check) TCP checksum
1193 */
1194static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1195 __be32 daddr, __wsum base)
1196{
1197 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1198}
1199
1200static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1201{
1202 return __skb_checksum_complete(skb);
1203}
1204
1205static inline bool tcp_checksum_complete(struct sk_buff *skb)
1206{
1207 return !skb_csum_unnecessary(skb) &&
1208 __tcp_checksum_complete(skb);
1209}
1210
1211/* Prequeue for VJ style copy to user, combined with checksumming. */
1212
1213static inline void tcp_prequeue_init(struct tcp_sock *tp)
1214{
1215 tp->ucopy.task = NULL;
1216 tp->ucopy.len = 0;
1217 tp->ucopy.memory = 0;
1218 skb_queue_head_init(&tp->ucopy.prequeue);
1219}
1220
1221bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1222bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1223int tcp_filter(struct sock *sk, struct sk_buff *skb);
1224
1225#undef STATE_TRACE
1226
1227#ifdef STATE_TRACE
1228static const char *statename[]={
1229 "Unused","Established","Syn Sent","Syn Recv",
1230 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1231 "Close Wait","Last ACK","Listen","Closing"
1232};
1233#endif
1234void tcp_set_state(struct sock *sk, int state);
1235
1236void tcp_done(struct sock *sk);
1237
1238int tcp_abort(struct sock *sk, int err);
1239
1240static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1241{
1242 rx_opt->dsack = 0;
1243 rx_opt->num_sacks = 0;
1244}
1245
1246u32 tcp_default_init_rwnd(u32 mss);
1247void tcp_cwnd_restart(struct sock *sk, s32 delta);
1248
1249static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1250{
1251 struct tcp_sock *tp = tcp_sk(sk);
1252 s32 delta;
1253
1254 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out)
1255 return;
1256 delta = tcp_time_stamp - tp->lsndtime;
1257 if (delta > inet_csk(sk)->icsk_rto)
1258 tcp_cwnd_restart(sk, delta);
1259}
1260
1261/* Determine a window scaling and initial window to offer. */
1262void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1263 __u32 *window_clamp, int wscale_ok,
1264 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1265
1266static inline int tcp_win_from_space(int space)
1267{
1268 return sysctl_tcp_adv_win_scale<=0 ?
1269 (space>>(-sysctl_tcp_adv_win_scale)) :
1270 space - (space>>sysctl_tcp_adv_win_scale);
1271}
1272
1273/* Note: caller must be prepared to deal with negative returns */
1274static inline int tcp_space(const struct sock *sk)
1275{
1276 return tcp_win_from_space(sk->sk_rcvbuf -
1277 atomic_read(&sk->sk_rmem_alloc));
1278}
1279
1280static inline int tcp_full_space(const struct sock *sk)
1281{
1282 return tcp_win_from_space(sk->sk_rcvbuf);
1283}
1284
1285extern void tcp_openreq_init_rwin(struct request_sock *req,
1286 const struct sock *sk_listener,
1287 const struct dst_entry *dst);
1288
1289void tcp_enter_memory_pressure(struct sock *sk);
1290
1291static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1292{
1293 struct net *net = sock_net((struct sock *)tp);
1294
1295 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1296}
1297
1298static inline int keepalive_time_when(const struct tcp_sock *tp)
1299{
1300 struct net *net = sock_net((struct sock *)tp);
1301
1302 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1303}
1304
1305static inline int keepalive_probes(const struct tcp_sock *tp)
1306{
1307 struct net *net = sock_net((struct sock *)tp);
1308
1309 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1310}
1311
1312static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1313{
1314 const struct inet_connection_sock *icsk = &tp->inet_conn;
1315
1316 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1317 tcp_time_stamp - tp->rcv_tstamp);
1318}
1319
1320static inline int tcp_fin_time(const struct sock *sk)
1321{
1322 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1323 const int rto = inet_csk(sk)->icsk_rto;
1324
1325 if (fin_timeout < (rto << 2) - (rto >> 1))
1326 fin_timeout = (rto << 2) - (rto >> 1);
1327
1328 return fin_timeout;
1329}
1330
1331static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1332 int paws_win)
1333{
1334 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1335 return true;
1336 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1337 return true;
1338 /*
1339 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1340 * then following tcp messages have valid values. Ignore 0 value,
1341 * or else 'negative' tsval might forbid us to accept their packets.
1342 */
1343 if (!rx_opt->ts_recent)
1344 return true;
1345 return false;
1346}
1347
1348static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1349 int rst)
1350{
1351 if (tcp_paws_check(rx_opt, 0))
1352 return false;
1353
1354 /* RST segments are not recommended to carry timestamp,
1355 and, if they do, it is recommended to ignore PAWS because
1356 "their cleanup function should take precedence over timestamps."
1357 Certainly, it is mistake. It is necessary to understand the reasons
1358 of this constraint to relax it: if peer reboots, clock may go
1359 out-of-sync and half-open connections will not be reset.
1360 Actually, the problem would be not existing if all
1361 the implementations followed draft about maintaining clock
1362 via reboots. Linux-2.2 DOES NOT!
1363
1364 However, we can relax time bounds for RST segments to MSL.
1365 */
1366 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1367 return false;
1368 return true;
1369}
1370
1371bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1372 int mib_idx, u32 *last_oow_ack_time);
1373
1374static inline void tcp_mib_init(struct net *net)
1375{
1376 /* See RFC 2012 */
1377 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1378 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1379 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1380 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1381}
1382
1383/* from STCP */
1384static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1385{
1386 tp->lost_skb_hint = NULL;
1387}
1388
1389static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1390{
1391 tcp_clear_retrans_hints_partial(tp);
1392 tp->retransmit_skb_hint = NULL;
1393}
1394
1395union tcp_md5_addr {
1396 struct in_addr a4;
1397#if IS_ENABLED(CONFIG_IPV6)
1398 struct in6_addr a6;
1399#endif
1400};
1401
1402/* - key database */
1403struct tcp_md5sig_key {
1404 struct hlist_node node;
1405 u8 keylen;
1406 u8 family; /* AF_INET or AF_INET6 */
1407 union tcp_md5_addr addr;
1408 u8 key[TCP_MD5SIG_MAXKEYLEN];
1409 struct rcu_head rcu;
1410};
1411
1412/* - sock block */
1413struct tcp_md5sig_info {
1414 struct hlist_head head;
1415 struct rcu_head rcu;
1416};
1417
1418/* - pseudo header */
1419struct tcp4_pseudohdr {
1420 __be32 saddr;
1421 __be32 daddr;
1422 __u8 pad;
1423 __u8 protocol;
1424 __be16 len;
1425};
1426
1427struct tcp6_pseudohdr {
1428 struct in6_addr saddr;
1429 struct in6_addr daddr;
1430 __be32 len;
1431 __be32 protocol; /* including padding */
1432};
1433
1434union tcp_md5sum_block {
1435 struct tcp4_pseudohdr ip4;
1436#if IS_ENABLED(CONFIG_IPV6)
1437 struct tcp6_pseudohdr ip6;
1438#endif
1439};
1440
1441/* - pool: digest algorithm, hash description and scratch buffer */
1442struct tcp_md5sig_pool {
1443 struct ahash_request *md5_req;
1444 void *scratch;
1445};
1446
1447/* - functions */
1448int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1449 const struct sock *sk, const struct sk_buff *skb);
1450int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1451 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1452int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1453 int family);
1454struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1455 const struct sock *addr_sk);
1456
1457#ifdef CONFIG_TCP_MD5SIG
1458struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1459 const union tcp_md5_addr *addr,
1460 int family);
1461#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1462#else
1463static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1464 const union tcp_md5_addr *addr,
1465 int family)
1466{
1467 return NULL;
1468}
1469#define tcp_twsk_md5_key(twsk) NULL
1470#endif
1471
1472bool tcp_alloc_md5sig_pool(void);
1473
1474struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1475static inline void tcp_put_md5sig_pool(void)
1476{
1477 local_bh_enable();
1478}
1479
1480int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1481 unsigned int header_len);
1482int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1483 const struct tcp_md5sig_key *key);
1484
1485/* From tcp_fastopen.c */
1486void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1487 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1488 unsigned long *last_syn_loss);
1489void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1490 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1491 u16 try_exp);
1492struct tcp_fastopen_request {
1493 /* Fast Open cookie. Size 0 means a cookie request */
1494 struct tcp_fastopen_cookie cookie;
1495 struct msghdr *data; /* data in MSG_FASTOPEN */
1496 size_t size;
1497 int copied; /* queued in tcp_connect() */
1498};
1499void tcp_free_fastopen_req(struct tcp_sock *tp);
1500
1501extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1502int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1503void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1504struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1505 struct request_sock *req,
1506 struct tcp_fastopen_cookie *foc,
1507 struct dst_entry *dst);
1508void tcp_fastopen_init_key_once(bool publish);
1509#define TCP_FASTOPEN_KEY_LENGTH 16
1510
1511/* Fastopen key context */
1512struct tcp_fastopen_context {
1513 struct crypto_cipher *tfm;
1514 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1515 struct rcu_head rcu;
1516};
1517
1518/* Latencies incurred by various limits for a sender. They are
1519 * chronograph-like stats that are mutually exclusive.
1520 */
1521enum tcp_chrono {
1522 TCP_CHRONO_UNSPEC,
1523 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1524 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1525 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1526 __TCP_CHRONO_MAX,
1527};
1528
1529void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1530void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1531
1532/* write queue abstraction */
1533static inline void tcp_write_queue_purge(struct sock *sk)
1534{
1535 struct sk_buff *skb;
1536
1537 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1538 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1539 sk_wmem_free_skb(sk, skb);
1540 sk_mem_reclaim(sk);
1541 tcp_clear_all_retrans_hints(tcp_sk(sk));
1542}
1543
1544static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1545{
1546 return skb_peek(&sk->sk_write_queue);
1547}
1548
1549static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1550{
1551 return skb_peek_tail(&sk->sk_write_queue);
1552}
1553
1554static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1555 const struct sk_buff *skb)
1556{
1557 return skb_queue_next(&sk->sk_write_queue, skb);
1558}
1559
1560static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1561 const struct sk_buff *skb)
1562{
1563 return skb_queue_prev(&sk->sk_write_queue, skb);
1564}
1565
1566#define tcp_for_write_queue(skb, sk) \
1567 skb_queue_walk(&(sk)->sk_write_queue, skb)
1568
1569#define tcp_for_write_queue_from(skb, sk) \
1570 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1571
1572#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1573 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1574
1575static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1576{
1577 return sk->sk_send_head;
1578}
1579
1580static inline bool tcp_skb_is_last(const struct sock *sk,
1581 const struct sk_buff *skb)
1582{
1583 return skb_queue_is_last(&sk->sk_write_queue, skb);
1584}
1585
1586static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1587{
1588 if (tcp_skb_is_last(sk, skb))
1589 sk->sk_send_head = NULL;
1590 else
1591 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1592}
1593
1594static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1595{
1596 if (sk->sk_send_head == skb_unlinked) {
1597 sk->sk_send_head = NULL;
1598 tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
1599 }
1600 if (tcp_sk(sk)->highest_sack == skb_unlinked)
1601 tcp_sk(sk)->highest_sack = NULL;
1602}
1603
1604static inline void tcp_init_send_head(struct sock *sk)
1605{
1606 sk->sk_send_head = NULL;
1607}
1608
1609static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1610{
1611 __skb_queue_tail(&sk->sk_write_queue, skb);
1612}
1613
1614static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1615{
1616 __tcp_add_write_queue_tail(sk, skb);
1617
1618 /* Queue it, remembering where we must start sending. */
1619 if (sk->sk_send_head == NULL) {
1620 sk->sk_send_head = skb;
1621 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1622
1623 if (tcp_sk(sk)->highest_sack == NULL)
1624 tcp_sk(sk)->highest_sack = skb;
1625 }
1626}
1627
1628static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1629{
1630 __skb_queue_head(&sk->sk_write_queue, skb);
1631}
1632
1633/* Insert buff after skb on the write queue of sk. */
1634static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1635 struct sk_buff *buff,
1636 struct sock *sk)
1637{
1638 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1639}
1640
1641/* Insert new before skb on the write queue of sk. */
1642static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1643 struct sk_buff *skb,
1644 struct sock *sk)
1645{
1646 __skb_queue_before(&sk->sk_write_queue, skb, new);
1647
1648 if (sk->sk_send_head == skb)
1649 sk->sk_send_head = new;
1650}
1651
1652static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1653{
1654 __skb_unlink(skb, &sk->sk_write_queue);
1655}
1656
1657static inline bool tcp_write_queue_empty(struct sock *sk)
1658{
1659 return skb_queue_empty(&sk->sk_write_queue);
1660}
1661
1662static inline void tcp_push_pending_frames(struct sock *sk)
1663{
1664 if (tcp_send_head(sk)) {
1665 struct tcp_sock *tp = tcp_sk(sk);
1666
1667 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1668 }
1669}
1670
1671/* Start sequence of the skb just after the highest skb with SACKed
1672 * bit, valid only if sacked_out > 0 or when the caller has ensured
1673 * validity by itself.
1674 */
1675static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1676{
1677 if (!tp->sacked_out)
1678 return tp->snd_una;
1679
1680 if (tp->highest_sack == NULL)
1681 return tp->snd_nxt;
1682
1683 return TCP_SKB_CB(tp->highest_sack)->seq;
1684}
1685
1686static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1687{
1688 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1689 tcp_write_queue_next(sk, skb);
1690}
1691
1692static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1693{
1694 return tcp_sk(sk)->highest_sack;
1695}
1696
1697static inline void tcp_highest_sack_reset(struct sock *sk)
1698{
1699 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1700}
1701
1702/* Called when old skb is about to be deleted (to be combined with new skb) */
1703static inline void tcp_highest_sack_combine(struct sock *sk,
1704 struct sk_buff *old,
1705 struct sk_buff *new)
1706{
1707 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1708 tcp_sk(sk)->highest_sack = new;
1709}
1710
1711/* This helper checks if socket has IP_TRANSPARENT set */
1712static inline bool inet_sk_transparent(const struct sock *sk)
1713{
1714 switch (sk->sk_state) {
1715 case TCP_TIME_WAIT:
1716 return inet_twsk(sk)->tw_transparent;
1717 case TCP_NEW_SYN_RECV:
1718 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1719 }
1720 return inet_sk(sk)->transparent;
1721}
1722
1723/* Determines whether this is a thin stream (which may suffer from
1724 * increased latency). Used to trigger latency-reducing mechanisms.
1725 */
1726static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1727{
1728 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1729}
1730
1731/* /proc */
1732enum tcp_seq_states {
1733 TCP_SEQ_STATE_LISTENING,
1734 TCP_SEQ_STATE_ESTABLISHED,
1735};
1736
1737int tcp_seq_open(struct inode *inode, struct file *file);
1738
1739struct tcp_seq_afinfo {
1740 char *name;
1741 sa_family_t family;
1742 const struct file_operations *seq_fops;
1743 struct seq_operations seq_ops;
1744};
1745
1746struct tcp_iter_state {
1747 struct seq_net_private p;
1748 sa_family_t family;
1749 enum tcp_seq_states state;
1750 struct sock *syn_wait_sk;
1751 int bucket, offset, sbucket, num;
1752 loff_t last_pos;
1753};
1754
1755int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1756void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1757
1758extern struct request_sock_ops tcp_request_sock_ops;
1759extern struct request_sock_ops tcp6_request_sock_ops;
1760
1761void tcp_v4_destroy_sock(struct sock *sk);
1762
1763struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1764 netdev_features_t features);
1765struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1766int tcp_gro_complete(struct sk_buff *skb);
1767
1768void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1769
1770static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1771{
1772 struct net *net = sock_net((struct sock *)tp);
1773 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1774}
1775
1776static inline bool tcp_stream_memory_free(const struct sock *sk)
1777{
1778 const struct tcp_sock *tp = tcp_sk(sk);
1779 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1780
1781 return notsent_bytes < tcp_notsent_lowat(tp);
1782}
1783
1784#ifdef CONFIG_PROC_FS
1785int tcp4_proc_init(void);
1786void tcp4_proc_exit(void);
1787#endif
1788
1789int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1790int tcp_conn_request(struct request_sock_ops *rsk_ops,
1791 const struct tcp_request_sock_ops *af_ops,
1792 struct sock *sk, struct sk_buff *skb);
1793
1794/* TCP af-specific functions */
1795struct tcp_sock_af_ops {
1796#ifdef CONFIG_TCP_MD5SIG
1797 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1798 const struct sock *addr_sk);
1799 int (*calc_md5_hash)(char *location,
1800 const struct tcp_md5sig_key *md5,
1801 const struct sock *sk,
1802 const struct sk_buff *skb);
1803 int (*md5_parse)(struct sock *sk,
1804 char __user *optval,
1805 int optlen);
1806#endif
1807};
1808
1809struct tcp_request_sock_ops {
1810 u16 mss_clamp;
1811#ifdef CONFIG_TCP_MD5SIG
1812 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1813 const struct sock *addr_sk);
1814 int (*calc_md5_hash) (char *location,
1815 const struct tcp_md5sig_key *md5,
1816 const struct sock *sk,
1817 const struct sk_buff *skb);
1818#endif
1819 void (*init_req)(struct request_sock *req,
1820 const struct sock *sk_listener,
1821 struct sk_buff *skb);
1822#ifdef CONFIG_SYN_COOKIES
1823 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1824 __u16 *mss);
1825#endif
1826 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1827 const struct request_sock *req,
1828 bool *strict);
1829 __u32 (*init_seq)(const struct sk_buff *skb, u32 *tsoff);
1830 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1831 struct flowi *fl, struct request_sock *req,
1832 struct tcp_fastopen_cookie *foc,
1833 enum tcp_synack_type synack_type);
1834};
1835
1836#ifdef CONFIG_SYN_COOKIES
1837static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1838 const struct sock *sk, struct sk_buff *skb,
1839 __u16 *mss)
1840{
1841 tcp_synq_overflow(sk);
1842 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1843 return ops->cookie_init_seq(skb, mss);
1844}
1845#else
1846static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1847 const struct sock *sk, struct sk_buff *skb,
1848 __u16 *mss)
1849{
1850 return 0;
1851}
1852#endif
1853
1854int tcpv4_offload_init(void);
1855
1856void tcp_v4_init(void);
1857void tcp_init(void);
1858
1859/* tcp_recovery.c */
1860
1861/* Flags to enable various loss recovery features. See below */
1862extern int sysctl_tcp_recovery;
1863
1864/* Use TCP RACK to detect (some) tail and retransmit losses */
1865#define TCP_RACK_LOST_RETRANS 0x1
1866
1867extern int tcp_rack_mark_lost(struct sock *sk);
1868
1869extern void tcp_rack_advance(struct tcp_sock *tp,
1870 const struct skb_mstamp *xmit_time, u8 sacked);
1871
1872/*
1873 * Save and compile IPv4 options, return a pointer to it
1874 */
1875static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
1876{
1877 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1878 struct ip_options_rcu *dopt = NULL;
1879
1880 if (opt->optlen) {
1881 int opt_size = sizeof(*dopt) + opt->optlen;
1882
1883 dopt = kmalloc(opt_size, GFP_ATOMIC);
1884 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
1885 kfree(dopt);
1886 dopt = NULL;
1887 }
1888 }
1889 return dopt;
1890}
1891
1892/* locally generated TCP pure ACKs have skb->truesize == 2
1893 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1894 * This is much faster than dissecting the packet to find out.
1895 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1896 */
1897static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1898{
1899 return skb->truesize == 2;
1900}
1901
1902static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1903{
1904 skb->truesize = 2;
1905}
1906
1907static inline int tcp_inq(struct sock *sk)
1908{
1909 struct tcp_sock *tp = tcp_sk(sk);
1910 int answ;
1911
1912 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1913 answ = 0;
1914 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1915 !tp->urg_data ||
1916 before(tp->urg_seq, tp->copied_seq) ||
1917 !before(tp->urg_seq, tp->rcv_nxt)) {
1918
1919 answ = tp->rcv_nxt - tp->copied_seq;
1920
1921 /* Subtract 1, if FIN was received */
1922 if (answ && sock_flag(sk, SOCK_DONE))
1923 answ--;
1924 } else {
1925 answ = tp->urg_seq - tp->copied_seq;
1926 }
1927
1928 return answ;
1929}
1930
1931int tcp_peek_len(struct socket *sock);
1932
1933static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1934{
1935 u16 segs_in;
1936
1937 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1938 tp->segs_in += segs_in;
1939 if (skb->len > tcp_hdrlen(skb))
1940 tp->data_segs_in += segs_in;
1941}
1942
1943/*
1944 * TCP listen path runs lockless.
1945 * We forced "struct sock" to be const qualified to make sure
1946 * we don't modify one of its field by mistake.
1947 * Here, we increment sk_drops which is an atomic_t, so we can safely
1948 * make sock writable again.
1949 */
1950static inline void tcp_listendrop(const struct sock *sk)
1951{
1952 atomic_inc(&((struct sock *)sk)->sk_drops);
1953 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
1954}
1955
1956#endif /* _TCP_H */