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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/tcp_ao.h>
41#include <net/inet_ecn.h>
42#include <net/dst.h>
43#include <net/mptcp.h>
44#include <net/xfrm.h>
45
46#include <linux/seq_file.h>
47#include <linux/memcontrol.h>
48#include <linux/bpf-cgroup.h>
49#include <linux/siphash.h>
50
51extern struct inet_hashinfo tcp_hashinfo;
52
53DECLARE_PER_CPU(unsigned int, tcp_orphan_count);
54int tcp_orphan_count_sum(void);
55
56DECLARE_PER_CPU(u32, tcp_tw_isn);
57
58void tcp_time_wait(struct sock *sk, int state, int timeo);
59
60#define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER)
61#define MAX_TCP_OPTION_SPACE 40
62#define TCP_MIN_SND_MSS 48
63#define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
64
65/*
66 * Never offer a window over 32767 without using window scaling. Some
67 * poor stacks do signed 16bit maths!
68 */
69#define MAX_TCP_WINDOW 32767U
70
71/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
72#define TCP_MIN_MSS 88U
73
74/* The initial MTU to use for probing */
75#define TCP_BASE_MSS 1024
76
77/* probing interval, default to 10 minutes as per RFC4821 */
78#define TCP_PROBE_INTERVAL 600
79
80/* Specify interval when tcp mtu probing will stop */
81#define TCP_PROBE_THRESHOLD 8
82
83/* After receiving this amount of duplicate ACKs fast retransmit starts. */
84#define TCP_FASTRETRANS_THRESH 3
85
86/* Maximal number of ACKs sent quickly to accelerate slow-start. */
87#define TCP_MAX_QUICKACKS 16U
88
89/* Maximal number of window scale according to RFC1323 */
90#define TCP_MAX_WSCALE 14U
91
92/* urg_data states */
93#define TCP_URG_VALID 0x0100
94#define TCP_URG_NOTYET 0x0200
95#define TCP_URG_READ 0x0400
96
97#define TCP_RETR1 3 /*
98 * This is how many retries it does before it
99 * tries to figure out if the gateway is
100 * down. Minimal RFC value is 3; it corresponds
101 * to ~3sec-8min depending on RTO.
102 */
103
104#define TCP_RETR2 15 /*
105 * This should take at least
106 * 90 minutes to time out.
107 * RFC1122 says that the limit is 100 sec.
108 * 15 is ~13-30min depending on RTO.
109 */
110
111#define TCP_SYN_RETRIES 6 /* This is how many retries are done
112 * when active opening a connection.
113 * RFC1122 says the minimum retry MUST
114 * be at least 180secs. Nevertheless
115 * this value is corresponding to
116 * 63secs of retransmission with the
117 * current initial RTO.
118 */
119
120#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
121 * when passive opening a connection.
122 * This is corresponding to 31secs of
123 * retransmission with the current
124 * initial RTO.
125 */
126
127#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
128 * state, about 60 seconds */
129#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
130 /* BSD style FIN_WAIT2 deadlock breaker.
131 * It used to be 3min, new value is 60sec,
132 * to combine FIN-WAIT-2 timeout with
133 * TIME-WAIT timer.
134 */
135#define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
136
137#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
138static_assert((1 << ATO_BITS) > TCP_DELACK_MAX);
139
140#if HZ >= 100
141#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
142#define TCP_ATO_MIN ((unsigned)(HZ/25))
143#else
144#define TCP_DELACK_MIN 4U
145#define TCP_ATO_MIN 4U
146#endif
147#define TCP_RTO_MAX ((unsigned)(120*HZ))
148#define TCP_RTO_MIN ((unsigned)(HZ/5))
149#define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
150
151#define TCP_TIMEOUT_MIN_US (2*USEC_PER_MSEC) /* Min TCP timeout in microsecs */
152
153#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
154#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
155 * used as a fallback RTO for the
156 * initial data transmission if no
157 * valid RTT sample has been acquired,
158 * most likely due to retrans in 3WHS.
159 */
160
161#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
162 * for local resources.
163 */
164#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
165#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
166#define TCP_KEEPALIVE_INTVL (75*HZ)
167
168#define MAX_TCP_KEEPIDLE 32767
169#define MAX_TCP_KEEPINTVL 32767
170#define MAX_TCP_KEEPCNT 127
171#define MAX_TCP_SYNCNT 127
172
173/* Ensure that TCP PAWS checks are relaxed after ~2147 seconds
174 * to avoid overflows. This assumes a clock smaller than 1 Mhz.
175 * Default clock is 1 Khz, tcp_usec_ts uses 1 Mhz.
176 */
177#define TCP_PAWS_WRAP (INT_MAX / USEC_PER_SEC)
178
179#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
180 * after this time. It should be equal
181 * (or greater than) TCP_TIMEWAIT_LEN
182 * to provide reliability equal to one
183 * provided by timewait state.
184 */
185#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
186 * timestamps. It must be less than
187 * minimal timewait lifetime.
188 */
189/*
190 * TCP option
191 */
192
193#define TCPOPT_NOP 1 /* Padding */
194#define TCPOPT_EOL 0 /* End of options */
195#define TCPOPT_MSS 2 /* Segment size negotiating */
196#define TCPOPT_WINDOW 3 /* Window scaling */
197#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
198#define TCPOPT_SACK 5 /* SACK Block */
199#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
200#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
201#define TCPOPT_AO 29 /* Authentication Option (RFC5925) */
202#define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */
203#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
204#define TCPOPT_EXP 254 /* Experimental */
205/* Magic number to be after the option value for sharing TCP
206 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
207 */
208#define TCPOPT_FASTOPEN_MAGIC 0xF989
209#define TCPOPT_SMC_MAGIC 0xE2D4C3D9
210
211/*
212 * TCP option lengths
213 */
214
215#define TCPOLEN_MSS 4
216#define TCPOLEN_WINDOW 3
217#define TCPOLEN_SACK_PERM 2
218#define TCPOLEN_TIMESTAMP 10
219#define TCPOLEN_MD5SIG 18
220#define TCPOLEN_FASTOPEN_BASE 2
221#define TCPOLEN_EXP_FASTOPEN_BASE 4
222#define TCPOLEN_EXP_SMC_BASE 6
223
224/* But this is what stacks really send out. */
225#define TCPOLEN_TSTAMP_ALIGNED 12
226#define TCPOLEN_WSCALE_ALIGNED 4
227#define TCPOLEN_SACKPERM_ALIGNED 4
228#define TCPOLEN_SACK_BASE 2
229#define TCPOLEN_SACK_BASE_ALIGNED 4
230#define TCPOLEN_SACK_PERBLOCK 8
231#define TCPOLEN_MD5SIG_ALIGNED 20
232#define TCPOLEN_MSS_ALIGNED 4
233#define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
234
235/* Flags in tp->nonagle */
236#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
237#define TCP_NAGLE_CORK 2 /* Socket is corked */
238#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
239
240/* TCP thin-stream limits */
241#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
242
243/* TCP initial congestion window as per rfc6928 */
244#define TCP_INIT_CWND 10
245
246/* Bit Flags for sysctl_tcp_fastopen */
247#define TFO_CLIENT_ENABLE 1
248#define TFO_SERVER_ENABLE 2
249#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
250
251/* Accept SYN data w/o any cookie option */
252#define TFO_SERVER_COOKIE_NOT_REQD 0x200
253
254/* Force enable TFO on all listeners, i.e., not requiring the
255 * TCP_FASTOPEN socket option.
256 */
257#define TFO_SERVER_WO_SOCKOPT1 0x400
258
259
260/* sysctl variables for tcp */
261extern int sysctl_tcp_max_orphans;
262extern long sysctl_tcp_mem[3];
263
264#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
265#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
266#define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
267
268extern atomic_long_t tcp_memory_allocated;
269DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
270
271extern struct percpu_counter tcp_sockets_allocated;
272extern unsigned long tcp_memory_pressure;
273
274/* optimized version of sk_under_memory_pressure() for TCP sockets */
275static inline bool tcp_under_memory_pressure(const struct sock *sk)
276{
277 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
278 mem_cgroup_under_socket_pressure(sk->sk_memcg))
279 return true;
280
281 return READ_ONCE(tcp_memory_pressure);
282}
283/*
284 * The next routines deal with comparing 32 bit unsigned ints
285 * and worry about wraparound (automatic with unsigned arithmetic).
286 */
287
288static inline bool before(__u32 seq1, __u32 seq2)
289{
290 return (__s32)(seq1-seq2) < 0;
291}
292#define after(seq2, seq1) before(seq1, seq2)
293
294/* is s2<=s1<=s3 ? */
295static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
296{
297 return seq3 - seq2 >= seq1 - seq2;
298}
299
300static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
301{
302 sk_wmem_queued_add(sk, -skb->truesize);
303 if (!skb_zcopy_pure(skb))
304 sk_mem_uncharge(sk, skb->truesize);
305 else
306 sk_mem_uncharge(sk, SKB_TRUESIZE(skb_end_offset(skb)));
307 __kfree_skb(skb);
308}
309
310void sk_forced_mem_schedule(struct sock *sk, int size);
311
312bool tcp_check_oom(const struct sock *sk, int shift);
313
314
315extern struct proto tcp_prot;
316
317#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
318#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
319#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
320#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
321
322void tcp_tasklet_init(void);
323
324int tcp_v4_err(struct sk_buff *skb, u32);
325
326void tcp_shutdown(struct sock *sk, int how);
327
328int tcp_v4_early_demux(struct sk_buff *skb);
329int tcp_v4_rcv(struct sk_buff *skb);
330
331void tcp_remove_empty_skb(struct sock *sk);
332int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
333int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
334int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
335 size_t size, struct ubuf_info *uarg);
336void tcp_splice_eof(struct socket *sock);
337int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
338int tcp_wmem_schedule(struct sock *sk, int copy);
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, int *karg);
346enum skb_drop_reason 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);
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, gfp_t gfp,
356 bool force_schedule);
357
358static inline void tcp_dec_quickack_mode(struct sock *sk)
359{
360 struct inet_connection_sock *icsk = inet_csk(sk);
361
362 if (icsk->icsk_ack.quick) {
363 /* How many ACKs S/ACKing new data have we sent? */
364 const unsigned int pkts = inet_csk_ack_scheduled(sk) ? 1 : 0;
365
366 if (pkts >= icsk->icsk_ack.quick) {
367 icsk->icsk_ack.quick = 0;
368 /* Leaving quickack mode we deflate ATO. */
369 icsk->icsk_ack.ato = TCP_ATO_MIN;
370 } else
371 icsk->icsk_ack.quick -= pkts;
372 }
373}
374
375#define TCP_ECN_OK 1
376#define TCP_ECN_QUEUE_CWR 2
377#define TCP_ECN_DEMAND_CWR 4
378#define TCP_ECN_SEEN 8
379
380enum tcp_tw_status {
381 TCP_TW_SUCCESS = 0,
382 TCP_TW_RST = 1,
383 TCP_TW_ACK = 2,
384 TCP_TW_SYN = 3
385};
386
387
388enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
389 struct sk_buff *skb,
390 const struct tcphdr *th,
391 u32 *tw_isn);
392struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
393 struct request_sock *req, bool fastopen,
394 bool *lost_race);
395enum skb_drop_reason tcp_child_process(struct sock *parent, struct sock *child,
396 struct sk_buff *skb);
397void tcp_enter_loss(struct sock *sk);
398void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
399void tcp_clear_retrans(struct tcp_sock *tp);
400void tcp_update_metrics(struct sock *sk);
401void tcp_init_metrics(struct sock *sk);
402void tcp_metrics_init(void);
403bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
404void __tcp_close(struct sock *sk, long timeout);
405void tcp_close(struct sock *sk, long timeout);
406void tcp_init_sock(struct sock *sk);
407void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb);
408__poll_t tcp_poll(struct file *file, struct socket *sock,
409 struct poll_table_struct *wait);
410int do_tcp_getsockopt(struct sock *sk, int level,
411 int optname, sockptr_t optval, sockptr_t optlen);
412int tcp_getsockopt(struct sock *sk, int level, int optname,
413 char __user *optval, int __user *optlen);
414bool tcp_bpf_bypass_getsockopt(int level, int optname);
415int do_tcp_setsockopt(struct sock *sk, int level, int optname,
416 sockptr_t optval, unsigned int optlen);
417int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
418 unsigned int optlen);
419void tcp_set_keepalive(struct sock *sk, int val);
420void tcp_syn_ack_timeout(const struct request_sock *req);
421int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
422 int flags, int *addr_len);
423int tcp_set_rcvlowat(struct sock *sk, int val);
424int tcp_set_window_clamp(struct sock *sk, int val);
425void tcp_update_recv_tstamps(struct sk_buff *skb,
426 struct scm_timestamping_internal *tss);
427void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
428 struct scm_timestamping_internal *tss);
429void tcp_data_ready(struct sock *sk);
430#ifdef CONFIG_MMU
431int tcp_mmap(struct file *file, struct socket *sock,
432 struct vm_area_struct *vma);
433#endif
434void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
435 struct tcp_options_received *opt_rx,
436 int estab, struct tcp_fastopen_cookie *foc);
437
438/*
439 * BPF SKB-less helpers
440 */
441u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
442 struct tcphdr *th, u32 *cookie);
443u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
444 struct tcphdr *th, u32 *cookie);
445u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss);
446u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
447 const struct tcp_request_sock_ops *af_ops,
448 struct sock *sk, struct tcphdr *th);
449/*
450 * TCP v4 functions exported for the inet6 API
451 */
452
453void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
454void tcp_v4_mtu_reduced(struct sock *sk);
455void tcp_req_err(struct sock *sk, u32 seq, bool abort);
456void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
457int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
458struct sock *tcp_create_openreq_child(const struct sock *sk,
459 struct request_sock *req,
460 struct sk_buff *skb);
461void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
462struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
463 struct request_sock *req,
464 struct dst_entry *dst,
465 struct request_sock *req_unhash,
466 bool *own_req);
467int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
468int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
469int tcp_connect(struct sock *sk);
470enum tcp_synack_type {
471 TCP_SYNACK_NORMAL,
472 TCP_SYNACK_FASTOPEN,
473 TCP_SYNACK_COOKIE,
474};
475struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
476 struct request_sock *req,
477 struct tcp_fastopen_cookie *foc,
478 enum tcp_synack_type synack_type,
479 struct sk_buff *syn_skb);
480int tcp_disconnect(struct sock *sk, int flags);
481
482void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
483int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
484void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
485
486/* From syncookies.c */
487struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
488 struct request_sock *req,
489 struct dst_entry *dst);
490int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th);
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 struct sock *sk, struct sk_buff *skb,
494 struct tcp_options_received *tcp_opt,
495 int mss, u32 tsoff);
496
497#if IS_ENABLED(CONFIG_BPF)
498struct bpf_tcp_req_attrs {
499 u32 rcv_tsval;
500 u32 rcv_tsecr;
501 u16 mss;
502 u8 rcv_wscale;
503 u8 snd_wscale;
504 u8 ecn_ok;
505 u8 wscale_ok;
506 u8 sack_ok;
507 u8 tstamp_ok;
508 u8 usec_ts_ok;
509 u8 reserved[3];
510};
511#endif
512
513#ifdef CONFIG_SYN_COOKIES
514
515/* Syncookies use a monotonic timer which increments every 60 seconds.
516 * This counter is used both as a hash input and partially encoded into
517 * the cookie value. A cookie is only validated further if the delta
518 * between the current counter value and the encoded one is less than this,
519 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
520 * the counter advances immediately after a cookie is generated).
521 */
522#define MAX_SYNCOOKIE_AGE 2
523#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
524#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
525
526/* syncookies: remember time of last synqueue overflow
527 * But do not dirty this field too often (once per second is enough)
528 * It is racy as we do not hold a lock, but race is very minor.
529 */
530static inline void tcp_synq_overflow(const struct sock *sk)
531{
532 unsigned int last_overflow;
533 unsigned int now = jiffies;
534
535 if (sk->sk_reuseport) {
536 struct sock_reuseport *reuse;
537
538 reuse = rcu_dereference(sk->sk_reuseport_cb);
539 if (likely(reuse)) {
540 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
541 if (!time_between32(now, last_overflow,
542 last_overflow + HZ))
543 WRITE_ONCE(reuse->synq_overflow_ts, now);
544 return;
545 }
546 }
547
548 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
549 if (!time_between32(now, last_overflow, last_overflow + HZ))
550 WRITE_ONCE(tcp_sk_rw(sk)->rx_opt.ts_recent_stamp, now);
551}
552
553/* syncookies: no recent synqueue overflow on this listening socket? */
554static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
555{
556 unsigned int last_overflow;
557 unsigned int now = jiffies;
558
559 if (sk->sk_reuseport) {
560 struct sock_reuseport *reuse;
561
562 reuse = rcu_dereference(sk->sk_reuseport_cb);
563 if (likely(reuse)) {
564 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
565 return !time_between32(now, last_overflow - HZ,
566 last_overflow +
567 TCP_SYNCOOKIE_VALID);
568 }
569 }
570
571 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
572
573 /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
574 * then we're under synflood. However, we have to use
575 * 'last_overflow - HZ' as lower bound. That's because a concurrent
576 * tcp_synq_overflow() could update .ts_recent_stamp after we read
577 * jiffies but before we store .ts_recent_stamp into last_overflow,
578 * which could lead to rejecting a valid syncookie.
579 */
580 return !time_between32(now, last_overflow - HZ,
581 last_overflow + TCP_SYNCOOKIE_VALID);
582}
583
584static inline u32 tcp_cookie_time(void)
585{
586 u64 val = get_jiffies_64();
587
588 do_div(val, TCP_SYNCOOKIE_PERIOD);
589 return val;
590}
591
592/* Convert one nsec 64bit timestamp to ts (ms or usec resolution) */
593static inline u64 tcp_ns_to_ts(bool usec_ts, u64 val)
594{
595 if (usec_ts)
596 return div_u64(val, NSEC_PER_USEC);
597
598 return div_u64(val, NSEC_PER_MSEC);
599}
600
601u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
602 u16 *mssp);
603__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
604u64 cookie_init_timestamp(struct request_sock *req, u64 now);
605bool cookie_timestamp_decode(const struct net *net,
606 struct tcp_options_received *opt);
607
608static inline bool cookie_ecn_ok(const struct net *net, const struct dst_entry *dst)
609{
610 return READ_ONCE(net->ipv4.sysctl_tcp_ecn) ||
611 dst_feature(dst, RTAX_FEATURE_ECN);
612}
613
614#if IS_ENABLED(CONFIG_BPF)
615static inline bool cookie_bpf_ok(struct sk_buff *skb)
616{
617 return skb->sk;
618}
619
620struct request_sock *cookie_bpf_check(struct sock *sk, struct sk_buff *skb);
621#else
622static inline bool cookie_bpf_ok(struct sk_buff *skb)
623{
624 return false;
625}
626
627static inline struct request_sock *cookie_bpf_check(struct net *net, struct sock *sk,
628 struct sk_buff *skb)
629{
630 return NULL;
631}
632#endif
633
634/* From net/ipv6/syncookies.c */
635int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th);
636struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
637
638u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
639 const struct tcphdr *th, u16 *mssp);
640__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
641#endif
642/* tcp_output.c */
643
644void tcp_skb_entail(struct sock *sk, struct sk_buff *skb);
645void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb);
646void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
647 int nonagle);
648int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
649int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
650void tcp_retransmit_timer(struct sock *sk);
651void tcp_xmit_retransmit_queue(struct sock *);
652void tcp_simple_retransmit(struct sock *);
653void tcp_enter_recovery(struct sock *sk, bool ece_ack);
654int tcp_trim_head(struct sock *, struct sk_buff *, u32);
655enum tcp_queue {
656 TCP_FRAG_IN_WRITE_QUEUE,
657 TCP_FRAG_IN_RTX_QUEUE,
658};
659int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
660 struct sk_buff *skb, u32 len,
661 unsigned int mss_now, gfp_t gfp);
662
663void tcp_send_probe0(struct sock *);
664int tcp_write_wakeup(struct sock *, int mib);
665void tcp_send_fin(struct sock *sk);
666void tcp_send_active_reset(struct sock *sk, gfp_t priority,
667 enum sk_rst_reason reason);
668int tcp_send_synack(struct sock *);
669void tcp_push_one(struct sock *, unsigned int mss_now);
670void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
671void tcp_send_ack(struct sock *sk);
672void tcp_send_delayed_ack(struct sock *sk);
673void tcp_send_loss_probe(struct sock *sk);
674bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
675void tcp_skb_collapse_tstamp(struct sk_buff *skb,
676 const struct sk_buff *next_skb);
677
678/* tcp_input.c */
679void tcp_rearm_rto(struct sock *sk);
680void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
681void tcp_done_with_error(struct sock *sk, int err);
682void tcp_reset(struct sock *sk, struct sk_buff *skb);
683void tcp_fin(struct sock *sk);
684void tcp_check_space(struct sock *sk);
685void tcp_sack_compress_send_ack(struct sock *sk);
686
687static inline void tcp_cleanup_skb(struct sk_buff *skb)
688{
689 skb_dst_drop(skb);
690 secpath_reset(skb);
691}
692
693static inline void tcp_add_receive_queue(struct sock *sk, struct sk_buff *skb)
694{
695 DEBUG_NET_WARN_ON_ONCE(skb_dst(skb));
696 DEBUG_NET_WARN_ON_ONCE(secpath_exists(skb));
697 __skb_queue_tail(&sk->sk_receive_queue, skb);
698}
699
700/* tcp_timer.c */
701void tcp_init_xmit_timers(struct sock *);
702static inline void tcp_clear_xmit_timers(struct sock *sk)
703{
704 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
705 __sock_put(sk);
706
707 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
708 __sock_put(sk);
709
710 inet_csk_clear_xmit_timers(sk);
711}
712
713unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
714unsigned int tcp_current_mss(struct sock *sk);
715u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when);
716
717/* Bound MSS / TSO packet size with the half of the window */
718static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
719{
720 int cutoff;
721
722 /* When peer uses tiny windows, there is no use in packetizing
723 * to sub-MSS pieces for the sake of SWS or making sure there
724 * are enough packets in the pipe for fast recovery.
725 *
726 * On the other hand, for extremely large MSS devices, handling
727 * smaller than MSS windows in this way does make sense.
728 */
729 if (tp->max_window > TCP_MSS_DEFAULT)
730 cutoff = (tp->max_window >> 1);
731 else
732 cutoff = tp->max_window;
733
734 if (cutoff && pktsize > cutoff)
735 return max_t(int, cutoff, 68U - tp->tcp_header_len);
736 else
737 return pktsize;
738}
739
740/* tcp.c */
741void tcp_get_info(struct sock *, struct tcp_info *);
742
743/* Read 'sendfile()'-style from a TCP socket */
744int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
745 sk_read_actor_t recv_actor);
746int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
747struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off);
748void tcp_read_done(struct sock *sk, size_t len);
749
750void tcp_initialize_rcv_mss(struct sock *sk);
751
752int tcp_mtu_to_mss(struct sock *sk, int pmtu);
753int tcp_mss_to_mtu(struct sock *sk, int mss);
754void tcp_mtup_init(struct sock *sk);
755
756static inline void tcp_bound_rto(struct sock *sk)
757{
758 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
759 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
760}
761
762static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
763{
764 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
765}
766
767static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
768{
769 /* mptcp hooks are only on the slow path */
770 if (sk_is_mptcp((struct sock *)tp))
771 return;
772
773 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
774 ntohl(TCP_FLAG_ACK) |
775 snd_wnd);
776}
777
778static inline void tcp_fast_path_on(struct tcp_sock *tp)
779{
780 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
781}
782
783static inline void tcp_fast_path_check(struct sock *sk)
784{
785 struct tcp_sock *tp = tcp_sk(sk);
786
787 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
788 tp->rcv_wnd &&
789 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
790 !tp->urg_data)
791 tcp_fast_path_on(tp);
792}
793
794u32 tcp_delack_max(const struct sock *sk);
795
796/* Compute the actual rto_min value */
797static inline u32 tcp_rto_min(const struct sock *sk)
798{
799 const struct dst_entry *dst = __sk_dst_get(sk);
800 u32 rto_min = inet_csk(sk)->icsk_rto_min;
801
802 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
803 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
804 return rto_min;
805}
806
807static inline u32 tcp_rto_min_us(const struct sock *sk)
808{
809 return jiffies_to_usecs(tcp_rto_min(sk));
810}
811
812static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
813{
814 return dst_metric_locked(dst, RTAX_CC_ALGO);
815}
816
817/* Minimum RTT in usec. ~0 means not available. */
818static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
819{
820 return minmax_get(&tp->rtt_min);
821}
822
823/* Compute the actual receive window we are currently advertising.
824 * Rcv_nxt can be after the window if our peer push more data
825 * than the offered window.
826 */
827static inline u32 tcp_receive_window(const struct tcp_sock *tp)
828{
829 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
830
831 if (win < 0)
832 win = 0;
833 return (u32) win;
834}
835
836/* Choose a new window, without checks for shrinking, and without
837 * scaling applied to the result. The caller does these things
838 * if necessary. This is a "raw" window selection.
839 */
840u32 __tcp_select_window(struct sock *sk);
841
842void tcp_send_window_probe(struct sock *sk);
843
844/* TCP uses 32bit jiffies to save some space.
845 * Note that this is different from tcp_time_stamp, which
846 * historically has been the same until linux-4.13.
847 */
848#define tcp_jiffies32 ((u32)jiffies)
849
850/*
851 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
852 * It is no longer tied to jiffies, but to 1 ms clock.
853 * Note: double check if you want to use tcp_jiffies32 instead of this.
854 */
855#define TCP_TS_HZ 1000
856
857static inline u64 tcp_clock_ns(void)
858{
859 return ktime_get_ns();
860}
861
862static inline u64 tcp_clock_us(void)
863{
864 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
865}
866
867static inline u64 tcp_clock_ms(void)
868{
869 return div_u64(tcp_clock_ns(), NSEC_PER_MSEC);
870}
871
872/* TCP Timestamp included in TS option (RFC 1323) can either use ms
873 * or usec resolution. Each socket carries a flag to select one or other
874 * resolution, as the route attribute could change anytime.
875 * Each flow must stick to initial resolution.
876 */
877static inline u32 tcp_clock_ts(bool usec_ts)
878{
879 return usec_ts ? tcp_clock_us() : tcp_clock_ms();
880}
881
882static inline u32 tcp_time_stamp_ms(const struct tcp_sock *tp)
883{
884 return div_u64(tp->tcp_mstamp, USEC_PER_MSEC);
885}
886
887static inline u32 tcp_time_stamp_ts(const struct tcp_sock *tp)
888{
889 if (tp->tcp_usec_ts)
890 return tp->tcp_mstamp;
891 return tcp_time_stamp_ms(tp);
892}
893
894void tcp_mstamp_refresh(struct tcp_sock *tp);
895
896static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
897{
898 return max_t(s64, t1 - t0, 0);
899}
900
901/* provide the departure time in us unit */
902static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
903{
904 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
905}
906
907/* Provide skb TSval in usec or ms unit */
908static inline u32 tcp_skb_timestamp_ts(bool usec_ts, const struct sk_buff *skb)
909{
910 if (usec_ts)
911 return tcp_skb_timestamp_us(skb);
912
913 return div_u64(skb->skb_mstamp_ns, NSEC_PER_MSEC);
914}
915
916static inline u32 tcp_tw_tsval(const struct tcp_timewait_sock *tcptw)
917{
918 return tcp_clock_ts(tcptw->tw_sk.tw_usec_ts) + tcptw->tw_ts_offset;
919}
920
921static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq)
922{
923 return tcp_clock_ts(treq->req_usec_ts) + treq->ts_off;
924}
925
926#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
927
928#define TCPHDR_FIN 0x01
929#define TCPHDR_SYN 0x02
930#define TCPHDR_RST 0x04
931#define TCPHDR_PSH 0x08
932#define TCPHDR_ACK 0x10
933#define TCPHDR_URG 0x20
934#define TCPHDR_ECE 0x40
935#define TCPHDR_CWR 0x80
936
937#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
938
939/* State flags for sacked in struct tcp_skb_cb */
940enum tcp_skb_cb_sacked_flags {
941 TCPCB_SACKED_ACKED = (1 << 0), /* SKB ACK'd by a SACK block */
942 TCPCB_SACKED_RETRANS = (1 << 1), /* SKB retransmitted */
943 TCPCB_LOST = (1 << 2), /* SKB is lost */
944 TCPCB_TAGBITS = (TCPCB_SACKED_ACKED | TCPCB_SACKED_RETRANS |
945 TCPCB_LOST), /* All tag bits */
946 TCPCB_REPAIRED = (1 << 4), /* SKB repaired (no skb_mstamp_ns) */
947 TCPCB_EVER_RETRANS = (1 << 7), /* Ever retransmitted frame */
948 TCPCB_RETRANS = (TCPCB_SACKED_RETRANS | TCPCB_EVER_RETRANS |
949 TCPCB_REPAIRED),
950};
951
952/* This is what the send packet queuing engine uses to pass
953 * TCP per-packet control information to the transmission code.
954 * We also store the host-order sequence numbers in here too.
955 * This is 44 bytes if IPV6 is enabled.
956 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
957 */
958struct tcp_skb_cb {
959 __u32 seq; /* Starting sequence number */
960 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
961 union {
962 /* Note :
963 * tcp_gso_segs/size are used in write queue only,
964 * cf tcp_skb_pcount()/tcp_skb_mss()
965 */
966 struct {
967 u16 tcp_gso_segs;
968 u16 tcp_gso_size;
969 };
970 };
971 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
972
973 __u8 sacked; /* State flags for SACK. */
974 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
975 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
976 eor:1, /* Is skb MSG_EOR marked? */
977 has_rxtstamp:1, /* SKB has a RX timestamp */
978 unused:5;
979 __u32 ack_seq; /* Sequence number ACK'd */
980 union {
981 struct {
982#define TCPCB_DELIVERED_CE_MASK ((1U<<20) - 1)
983 /* There is space for up to 24 bytes */
984 __u32 is_app_limited:1, /* cwnd not fully used? */
985 delivered_ce:20,
986 unused:11;
987 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
988 __u32 delivered;
989 /* start of send pipeline phase */
990 u64 first_tx_mstamp;
991 /* when we reached the "delivered" count */
992 u64 delivered_mstamp;
993 } tx; /* only used for outgoing skbs */
994 union {
995 struct inet_skb_parm h4;
996#if IS_ENABLED(CONFIG_IPV6)
997 struct inet6_skb_parm h6;
998#endif
999 } header; /* For incoming skbs */
1000 };
1001};
1002
1003#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
1004
1005extern const struct inet_connection_sock_af_ops ipv4_specific;
1006
1007#if IS_ENABLED(CONFIG_IPV6)
1008/* This is the variant of inet6_iif() that must be used by TCP,
1009 * as TCP moves IP6CB into a different location in skb->cb[]
1010 */
1011static inline int tcp_v6_iif(const struct sk_buff *skb)
1012{
1013 return TCP_SKB_CB(skb)->header.h6.iif;
1014}
1015
1016static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
1017{
1018 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
1019
1020 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
1021}
1022
1023/* TCP_SKB_CB reference means this can not be used from early demux */
1024static inline int tcp_v6_sdif(const struct sk_buff *skb)
1025{
1026#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
1027 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
1028 return TCP_SKB_CB(skb)->header.h6.iif;
1029#endif
1030 return 0;
1031}
1032
1033extern const struct inet_connection_sock_af_ops ipv6_specific;
1034
1035INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
1036INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
1037void tcp_v6_early_demux(struct sk_buff *skb);
1038
1039#endif
1040
1041/* TCP_SKB_CB reference means this can not be used from early demux */
1042static inline int tcp_v4_sdif(struct sk_buff *skb)
1043{
1044#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
1045 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
1046 return TCP_SKB_CB(skb)->header.h4.iif;
1047#endif
1048 return 0;
1049}
1050
1051/* Due to TSO, an SKB can be composed of multiple actual
1052 * packets. To keep these tracked properly, we use this.
1053 */
1054static inline int tcp_skb_pcount(const struct sk_buff *skb)
1055{
1056 return TCP_SKB_CB(skb)->tcp_gso_segs;
1057}
1058
1059static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
1060{
1061 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
1062}
1063
1064static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
1065{
1066 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
1067}
1068
1069/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
1070static inline int tcp_skb_mss(const struct sk_buff *skb)
1071{
1072 return TCP_SKB_CB(skb)->tcp_gso_size;
1073}
1074
1075static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
1076{
1077 return likely(!TCP_SKB_CB(skb)->eor);
1078}
1079
1080static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
1081 const struct sk_buff *from)
1082{
1083 /* skb_cmp_decrypted() not needed, use tcp_write_collapse_fence() */
1084 return likely(tcp_skb_can_collapse_to(to) &&
1085 mptcp_skb_can_collapse(to, from) &&
1086 skb_pure_zcopy_same(to, from) &&
1087 skb_frags_readable(to) == skb_frags_readable(from));
1088}
1089
1090static inline bool tcp_skb_can_collapse_rx(const struct sk_buff *to,
1091 const struct sk_buff *from)
1092{
1093 return likely(mptcp_skb_can_collapse(to, from) &&
1094 !skb_cmp_decrypted(to, from));
1095}
1096
1097/* Events passed to congestion control interface */
1098enum tcp_ca_event {
1099 CA_EVENT_TX_START, /* first transmit when no packets in flight */
1100 CA_EVENT_CWND_RESTART, /* congestion window restart */
1101 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
1102 CA_EVENT_LOSS, /* loss timeout */
1103 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
1104 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
1105};
1106
1107/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1108enum tcp_ca_ack_event_flags {
1109 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
1110 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
1111 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
1112};
1113
1114/*
1115 * Interface for adding new TCP congestion control handlers
1116 */
1117#define TCP_CA_NAME_MAX 16
1118#define TCP_CA_MAX 128
1119#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
1120
1121#define TCP_CA_UNSPEC 0
1122
1123/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1124#define TCP_CONG_NON_RESTRICTED 0x1
1125/* Requires ECN/ECT set on all packets */
1126#define TCP_CONG_NEEDS_ECN 0x2
1127#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
1128
1129union tcp_cc_info;
1130
1131struct ack_sample {
1132 u32 pkts_acked;
1133 s32 rtt_us;
1134 u32 in_flight;
1135};
1136
1137/* A rate sample measures the number of (original/retransmitted) data
1138 * packets delivered "delivered" over an interval of time "interval_us".
1139 * The tcp_rate.c code fills in the rate sample, and congestion
1140 * control modules that define a cong_control function to run at the end
1141 * of ACK processing can optionally chose to consult this sample when
1142 * setting cwnd and pacing rate.
1143 * A sample is invalid if "delivered" or "interval_us" is negative.
1144 */
1145struct rate_sample {
1146 u64 prior_mstamp; /* starting timestamp for interval */
1147 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1148 u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */
1149 s32 delivered; /* number of packets delivered over interval */
1150 s32 delivered_ce; /* number of packets delivered w/ CE marks*/
1151 long interval_us; /* time for tp->delivered to incr "delivered" */
1152 u32 snd_interval_us; /* snd interval for delivered packets */
1153 u32 rcv_interval_us; /* rcv interval for delivered packets */
1154 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1155 int losses; /* number of packets marked lost upon ACK */
1156 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1157 u32 prior_in_flight; /* in flight before this ACK */
1158 u32 last_end_seq; /* end_seq of most recently ACKed packet */
1159 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1160 bool is_retrans; /* is sample from retransmission? */
1161 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1162};
1163
1164struct tcp_congestion_ops {
1165/* fast path fields are put first to fill one cache line */
1166
1167 /* return slow start threshold (required) */
1168 u32 (*ssthresh)(struct sock *sk);
1169
1170 /* do new cwnd calculation (required) */
1171 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1172
1173 /* call before changing ca_state (optional) */
1174 void (*set_state)(struct sock *sk, u8 new_state);
1175
1176 /* call when cwnd event occurs (optional) */
1177 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1178
1179 /* call when ack arrives (optional) */
1180 void (*in_ack_event)(struct sock *sk, u32 flags);
1181
1182 /* hook for packet ack accounting (optional) */
1183 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1184
1185 /* override sysctl_tcp_min_tso_segs */
1186 u32 (*min_tso_segs)(struct sock *sk);
1187
1188 /* call when packets are delivered to update cwnd and pacing rate,
1189 * after all the ca_state processing. (optional)
1190 */
1191 void (*cong_control)(struct sock *sk, u32 ack, int flag, const struct rate_sample *rs);
1192
1193
1194 /* new value of cwnd after loss (required) */
1195 u32 (*undo_cwnd)(struct sock *sk);
1196 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1197 u32 (*sndbuf_expand)(struct sock *sk);
1198
1199/* control/slow paths put last */
1200 /* get info for inet_diag (optional) */
1201 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1202 union tcp_cc_info *info);
1203
1204 char name[TCP_CA_NAME_MAX];
1205 struct module *owner;
1206 struct list_head list;
1207 u32 key;
1208 u32 flags;
1209
1210 /* initialize private data (optional) */
1211 void (*init)(struct sock *sk);
1212 /* cleanup private data (optional) */
1213 void (*release)(struct sock *sk);
1214} ____cacheline_aligned_in_smp;
1215
1216int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1217void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1218int tcp_update_congestion_control(struct tcp_congestion_ops *type,
1219 struct tcp_congestion_ops *old_type);
1220int tcp_validate_congestion_control(struct tcp_congestion_ops *ca);
1221
1222void tcp_assign_congestion_control(struct sock *sk);
1223void tcp_init_congestion_control(struct sock *sk);
1224void tcp_cleanup_congestion_control(struct sock *sk);
1225int tcp_set_default_congestion_control(struct net *net, const char *name);
1226void tcp_get_default_congestion_control(struct net *net, char *name);
1227void tcp_get_available_congestion_control(char *buf, size_t len);
1228void tcp_get_allowed_congestion_control(char *buf, size_t len);
1229int tcp_set_allowed_congestion_control(char *allowed);
1230int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1231 bool cap_net_admin);
1232u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1233void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1234
1235u32 tcp_reno_ssthresh(struct sock *sk);
1236u32 tcp_reno_undo_cwnd(struct sock *sk);
1237void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1238extern struct tcp_congestion_ops tcp_reno;
1239
1240struct tcp_congestion_ops *tcp_ca_find(const char *name);
1241struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1242u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
1243#ifdef CONFIG_INET
1244char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1245#else
1246static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1247{
1248 return NULL;
1249}
1250#endif
1251
1252static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1253{
1254 const struct inet_connection_sock *icsk = inet_csk(sk);
1255
1256 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1257}
1258
1259static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1260{
1261 const struct inet_connection_sock *icsk = inet_csk(sk);
1262
1263 if (icsk->icsk_ca_ops->cwnd_event)
1264 icsk->icsk_ca_ops->cwnd_event(sk, event);
1265}
1266
1267/* From tcp_cong.c */
1268void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
1269
1270/* From tcp_rate.c */
1271void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1272void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1273 struct rate_sample *rs);
1274void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1275 bool is_sack_reneg, struct rate_sample *rs);
1276void tcp_rate_check_app_limited(struct sock *sk);
1277
1278static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
1279{
1280 return t1 > t2 || (t1 == t2 && after(seq1, seq2));
1281}
1282
1283/* These functions determine how the current flow behaves in respect of SACK
1284 * handling. SACK is negotiated with the peer, and therefore it can vary
1285 * between different flows.
1286 *
1287 * tcp_is_sack - SACK enabled
1288 * tcp_is_reno - No SACK
1289 */
1290static inline int tcp_is_sack(const struct tcp_sock *tp)
1291{
1292 return likely(tp->rx_opt.sack_ok);
1293}
1294
1295static inline bool tcp_is_reno(const struct tcp_sock *tp)
1296{
1297 return !tcp_is_sack(tp);
1298}
1299
1300static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1301{
1302 return tp->sacked_out + tp->lost_out;
1303}
1304
1305/* This determines how many packets are "in the network" to the best
1306 * of our knowledge. In many cases it is conservative, but where
1307 * detailed information is available from the receiver (via SACK
1308 * blocks etc.) we can make more aggressive calculations.
1309 *
1310 * Use this for decisions involving congestion control, use just
1311 * tp->packets_out to determine if the send queue is empty or not.
1312 *
1313 * Read this equation as:
1314 *
1315 * "Packets sent once on transmission queue" MINUS
1316 * "Packets left network, but not honestly ACKed yet" PLUS
1317 * "Packets fast retransmitted"
1318 */
1319static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1320{
1321 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1322}
1323
1324#define TCP_INFINITE_SSTHRESH 0x7fffffff
1325
1326static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
1327{
1328 return tp->snd_cwnd;
1329}
1330
1331static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
1332{
1333 WARN_ON_ONCE((int)val <= 0);
1334 tp->snd_cwnd = val;
1335}
1336
1337static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1338{
1339 return tcp_snd_cwnd(tp) < tp->snd_ssthresh;
1340}
1341
1342static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1343{
1344 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1345}
1346
1347static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1348{
1349 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1350 (1 << inet_csk(sk)->icsk_ca_state);
1351}
1352
1353/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1354 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1355 * ssthresh.
1356 */
1357static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1358{
1359 const struct tcp_sock *tp = tcp_sk(sk);
1360
1361 if (tcp_in_cwnd_reduction(sk))
1362 return tp->snd_ssthresh;
1363 else
1364 return max(tp->snd_ssthresh,
1365 ((tcp_snd_cwnd(tp) >> 1) +
1366 (tcp_snd_cwnd(tp) >> 2)));
1367}
1368
1369/* Use define here intentionally to get WARN_ON location shown at the caller */
1370#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1371
1372void tcp_enter_cwr(struct sock *sk);
1373__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1374
1375/* The maximum number of MSS of available cwnd for which TSO defers
1376 * sending if not using sysctl_tcp_tso_win_divisor.
1377 */
1378static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1379{
1380 return 3;
1381}
1382
1383/* Returns end sequence number of the receiver's advertised window */
1384static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1385{
1386 return tp->snd_una + tp->snd_wnd;
1387}
1388
1389/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1390 * flexible approach. The RFC suggests cwnd should not be raised unless
1391 * it was fully used previously. And that's exactly what we do in
1392 * congestion avoidance mode. But in slow start we allow cwnd to grow
1393 * as long as the application has used half the cwnd.
1394 * Example :
1395 * cwnd is 10 (IW10), but application sends 9 frames.
1396 * We allow cwnd to reach 18 when all frames are ACKed.
1397 * This check is safe because it's as aggressive as slow start which already
1398 * risks 100% overshoot. The advantage is that we discourage application to
1399 * either send more filler packets or data to artificially blow up the cwnd
1400 * usage, and allow application-limited process to probe bw more aggressively.
1401 */
1402static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1403{
1404 const struct tcp_sock *tp = tcp_sk(sk);
1405
1406 if (tp->is_cwnd_limited)
1407 return true;
1408
1409 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1410 if (tcp_in_slow_start(tp))
1411 return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out;
1412
1413 return false;
1414}
1415
1416/* BBR congestion control needs pacing.
1417 * Same remark for SO_MAX_PACING_RATE.
1418 * sch_fq packet scheduler is efficiently handling pacing,
1419 * but is not always installed/used.
1420 * Return true if TCP stack should pace packets itself.
1421 */
1422static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1423{
1424 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1425}
1426
1427/* Estimates in how many jiffies next packet for this flow can be sent.
1428 * Scheduling a retransmit timer too early would be silly.
1429 */
1430static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1431{
1432 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1433
1434 return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1435}
1436
1437static inline void tcp_reset_xmit_timer(struct sock *sk,
1438 const int what,
1439 unsigned long when,
1440 const unsigned long max_when)
1441{
1442 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1443 max_when);
1444}
1445
1446/* Something is really bad, we could not queue an additional packet,
1447 * because qdisc is full or receiver sent a 0 window, or we are paced.
1448 * We do not want to add fuel to the fire, or abort too early,
1449 * so make sure the timer we arm now is at least 200ms in the future,
1450 * regardless of current icsk_rto value (as it could be ~2ms)
1451 */
1452static inline unsigned long tcp_probe0_base(const struct sock *sk)
1453{
1454 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1455}
1456
1457/* Variant of inet_csk_rto_backoff() used for zero window probes */
1458static inline unsigned long tcp_probe0_when(const struct sock *sk,
1459 unsigned long max_when)
1460{
1461 u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1,
1462 inet_csk(sk)->icsk_backoff);
1463 u64 when = (u64)tcp_probe0_base(sk) << backoff;
1464
1465 return (unsigned long)min_t(u64, when, max_when);
1466}
1467
1468static inline void tcp_check_probe_timer(struct sock *sk)
1469{
1470 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1471 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1472 tcp_probe0_base(sk), TCP_RTO_MAX);
1473}
1474
1475static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1476{
1477 tp->snd_wl1 = seq;
1478}
1479
1480static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1481{
1482 tp->snd_wl1 = seq;
1483}
1484
1485/*
1486 * Calculate(/check) TCP checksum
1487 */
1488static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1489 __be32 daddr, __wsum base)
1490{
1491 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1492}
1493
1494static inline bool tcp_checksum_complete(struct sk_buff *skb)
1495{
1496 return !skb_csum_unnecessary(skb) &&
1497 __skb_checksum_complete(skb);
1498}
1499
1500bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
1501 enum skb_drop_reason *reason);
1502
1503
1504int tcp_filter(struct sock *sk, struct sk_buff *skb);
1505void tcp_set_state(struct sock *sk, int state);
1506void tcp_done(struct sock *sk);
1507int tcp_abort(struct sock *sk, int err);
1508
1509static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1510{
1511 rx_opt->dsack = 0;
1512 rx_opt->num_sacks = 0;
1513}
1514
1515void tcp_cwnd_restart(struct sock *sk, s32 delta);
1516
1517static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1518{
1519 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1520 struct tcp_sock *tp = tcp_sk(sk);
1521 s32 delta;
1522
1523 if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) ||
1524 tp->packets_out || ca_ops->cong_control)
1525 return;
1526 delta = tcp_jiffies32 - tp->lsndtime;
1527 if (delta > inet_csk(sk)->icsk_rto)
1528 tcp_cwnd_restart(sk, delta);
1529}
1530
1531/* Determine a window scaling and initial window to offer. */
1532void tcp_select_initial_window(const struct sock *sk, int __space,
1533 __u32 mss, __u32 *rcv_wnd,
1534 __u32 *window_clamp, int wscale_ok,
1535 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1536
1537static inline int __tcp_win_from_space(u8 scaling_ratio, int space)
1538{
1539 s64 scaled_space = (s64)space * scaling_ratio;
1540
1541 return scaled_space >> TCP_RMEM_TO_WIN_SCALE;
1542}
1543
1544static inline int tcp_win_from_space(const struct sock *sk, int space)
1545{
1546 return __tcp_win_from_space(tcp_sk(sk)->scaling_ratio, space);
1547}
1548
1549/* inverse of __tcp_win_from_space() */
1550static inline int __tcp_space_from_win(u8 scaling_ratio, int win)
1551{
1552 u64 val = (u64)win << TCP_RMEM_TO_WIN_SCALE;
1553
1554 do_div(val, scaling_ratio);
1555 return val;
1556}
1557
1558static inline int tcp_space_from_win(const struct sock *sk, int win)
1559{
1560 return __tcp_space_from_win(tcp_sk(sk)->scaling_ratio, win);
1561}
1562
1563/* Assume a 50% default for skb->len/skb->truesize ratio.
1564 * This may be adjusted later in tcp_measure_rcv_mss().
1565 */
1566#define TCP_DEFAULT_SCALING_RATIO (1 << (TCP_RMEM_TO_WIN_SCALE - 1))
1567
1568static inline void tcp_scaling_ratio_init(struct sock *sk)
1569{
1570 tcp_sk(sk)->scaling_ratio = TCP_DEFAULT_SCALING_RATIO;
1571}
1572
1573/* Note: caller must be prepared to deal with negative returns */
1574static inline int tcp_space(const struct sock *sk)
1575{
1576 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1577 READ_ONCE(sk->sk_backlog.len) -
1578 atomic_read(&sk->sk_rmem_alloc));
1579}
1580
1581static inline int tcp_full_space(const struct sock *sk)
1582{
1583 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1584}
1585
1586static inline void __tcp_adjust_rcv_ssthresh(struct sock *sk, u32 new_ssthresh)
1587{
1588 int unused_mem = sk_unused_reserved_mem(sk);
1589 struct tcp_sock *tp = tcp_sk(sk);
1590
1591 tp->rcv_ssthresh = min(tp->rcv_ssthresh, new_ssthresh);
1592 if (unused_mem)
1593 tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh,
1594 tcp_win_from_space(sk, unused_mem));
1595}
1596
1597static inline void tcp_adjust_rcv_ssthresh(struct sock *sk)
1598{
1599 __tcp_adjust_rcv_ssthresh(sk, 4U * tcp_sk(sk)->advmss);
1600}
1601
1602void tcp_cleanup_rbuf(struct sock *sk, int copied);
1603void __tcp_cleanup_rbuf(struct sock *sk, int copied);
1604
1605
1606/* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1607 * If 87.5 % (7/8) of the space has been consumed, we want to override
1608 * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1609 * len/truesize ratio.
1610 */
1611static inline bool tcp_rmem_pressure(const struct sock *sk)
1612{
1613 int rcvbuf, threshold;
1614
1615 if (tcp_under_memory_pressure(sk))
1616 return true;
1617
1618 rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1619 threshold = rcvbuf - (rcvbuf >> 3);
1620
1621 return atomic_read(&sk->sk_rmem_alloc) > threshold;
1622}
1623
1624static inline bool tcp_epollin_ready(const struct sock *sk, int target)
1625{
1626 const struct tcp_sock *tp = tcp_sk(sk);
1627 int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);
1628
1629 if (avail <= 0)
1630 return false;
1631
1632 return (avail >= target) || tcp_rmem_pressure(sk) ||
1633 (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss);
1634}
1635
1636extern void tcp_openreq_init_rwin(struct request_sock *req,
1637 const struct sock *sk_listener,
1638 const struct dst_entry *dst);
1639
1640void tcp_enter_memory_pressure(struct sock *sk);
1641void tcp_leave_memory_pressure(struct sock *sk);
1642
1643static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1644{
1645 struct net *net = sock_net((struct sock *)tp);
1646 int val;
1647
1648 /* Paired with WRITE_ONCE() in tcp_sock_set_keepintvl()
1649 * and do_tcp_setsockopt().
1650 */
1651 val = READ_ONCE(tp->keepalive_intvl);
1652
1653 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
1654}
1655
1656static inline int keepalive_time_when(const struct tcp_sock *tp)
1657{
1658 struct net *net = sock_net((struct sock *)tp);
1659 int val;
1660
1661 /* Paired with WRITE_ONCE() in tcp_sock_set_keepidle_locked() */
1662 val = READ_ONCE(tp->keepalive_time);
1663
1664 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
1665}
1666
1667static inline int keepalive_probes(const struct tcp_sock *tp)
1668{
1669 struct net *net = sock_net((struct sock *)tp);
1670 int val;
1671
1672 /* Paired with WRITE_ONCE() in tcp_sock_set_keepcnt()
1673 * and do_tcp_setsockopt().
1674 */
1675 val = READ_ONCE(tp->keepalive_probes);
1676
1677 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes);
1678}
1679
1680static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1681{
1682 const struct inet_connection_sock *icsk = &tp->inet_conn;
1683
1684 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1685 tcp_jiffies32 - tp->rcv_tstamp);
1686}
1687
1688static inline int tcp_fin_time(const struct sock *sk)
1689{
1690 int fin_timeout = tcp_sk(sk)->linger2 ? :
1691 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout);
1692 const int rto = inet_csk(sk)->icsk_rto;
1693
1694 if (fin_timeout < (rto << 2) - (rto >> 1))
1695 fin_timeout = (rto << 2) - (rto >> 1);
1696
1697 return fin_timeout;
1698}
1699
1700static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1701 int paws_win)
1702{
1703 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1704 return true;
1705 if (unlikely(!time_before32(ktime_get_seconds(),
1706 rx_opt->ts_recent_stamp + TCP_PAWS_WRAP)))
1707 return true;
1708 /*
1709 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1710 * then following tcp messages have valid values. Ignore 0 value,
1711 * or else 'negative' tsval might forbid us to accept their packets.
1712 */
1713 if (!rx_opt->ts_recent)
1714 return true;
1715 return false;
1716}
1717
1718static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1719 int rst)
1720{
1721 if (tcp_paws_check(rx_opt, 0))
1722 return false;
1723
1724 /* RST segments are not recommended to carry timestamp,
1725 and, if they do, it is recommended to ignore PAWS because
1726 "their cleanup function should take precedence over timestamps."
1727 Certainly, it is mistake. It is necessary to understand the reasons
1728 of this constraint to relax it: if peer reboots, clock may go
1729 out-of-sync and half-open connections will not be reset.
1730 Actually, the problem would be not existing if all
1731 the implementations followed draft about maintaining clock
1732 via reboots. Linux-2.2 DOES NOT!
1733
1734 However, we can relax time bounds for RST segments to MSL.
1735 */
1736 if (rst && !time_before32(ktime_get_seconds(),
1737 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1738 return false;
1739 return true;
1740}
1741
1742bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1743 int mib_idx, u32 *last_oow_ack_time);
1744
1745static inline void tcp_mib_init(struct net *net)
1746{
1747 /* See RFC 2012 */
1748 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1749 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1750 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1751 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1752}
1753
1754/* from STCP */
1755static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1756{
1757 tp->lost_skb_hint = NULL;
1758}
1759
1760static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1761{
1762 tcp_clear_retrans_hints_partial(tp);
1763 tp->retransmit_skb_hint = NULL;
1764}
1765
1766#define tcp_md5_addr tcp_ao_addr
1767
1768/* - key database */
1769struct tcp_md5sig_key {
1770 struct hlist_node node;
1771 u8 keylen;
1772 u8 family; /* AF_INET or AF_INET6 */
1773 u8 prefixlen;
1774 u8 flags;
1775 union tcp_md5_addr addr;
1776 int l3index; /* set if key added with L3 scope */
1777 u8 key[TCP_MD5SIG_MAXKEYLEN];
1778 struct rcu_head rcu;
1779};
1780
1781/* - sock block */
1782struct tcp_md5sig_info {
1783 struct hlist_head head;
1784 struct rcu_head rcu;
1785};
1786
1787/* - pseudo header */
1788struct tcp4_pseudohdr {
1789 __be32 saddr;
1790 __be32 daddr;
1791 __u8 pad;
1792 __u8 protocol;
1793 __be16 len;
1794};
1795
1796struct tcp6_pseudohdr {
1797 struct in6_addr saddr;
1798 struct in6_addr daddr;
1799 __be32 len;
1800 __be32 protocol; /* including padding */
1801};
1802
1803union tcp_md5sum_block {
1804 struct tcp4_pseudohdr ip4;
1805#if IS_ENABLED(CONFIG_IPV6)
1806 struct tcp6_pseudohdr ip6;
1807#endif
1808};
1809
1810/*
1811 * struct tcp_sigpool - per-CPU pool of ahash_requests
1812 * @scratch: per-CPU temporary area, that can be used between
1813 * tcp_sigpool_start() and tcp_sigpool_end() to perform
1814 * crypto request
1815 * @req: pre-allocated ahash request
1816 */
1817struct tcp_sigpool {
1818 void *scratch;
1819 struct ahash_request *req;
1820};
1821
1822int tcp_sigpool_alloc_ahash(const char *alg, size_t scratch_size);
1823void tcp_sigpool_get(unsigned int id);
1824void tcp_sigpool_release(unsigned int id);
1825int tcp_sigpool_hash_skb_data(struct tcp_sigpool *hp,
1826 const struct sk_buff *skb,
1827 unsigned int header_len);
1828
1829/**
1830 * tcp_sigpool_start - disable bh and start using tcp_sigpool_ahash
1831 * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
1832 * @c: returned tcp_sigpool for usage (uninitialized on failure)
1833 *
1834 * Returns 0 on success, error otherwise.
1835 */
1836int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c);
1837/**
1838 * tcp_sigpool_end - enable bh and stop using tcp_sigpool
1839 * @c: tcp_sigpool context that was returned by tcp_sigpool_start()
1840 */
1841void tcp_sigpool_end(struct tcp_sigpool *c);
1842size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len);
1843/* - functions */
1844int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1845 const struct sock *sk, const struct sk_buff *skb);
1846int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1847 int family, u8 prefixlen, int l3index, u8 flags,
1848 const u8 *newkey, u8 newkeylen);
1849int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr,
1850 int family, u8 prefixlen, int l3index,
1851 struct tcp_md5sig_key *key);
1852
1853int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1854 int family, u8 prefixlen, int l3index, u8 flags);
1855void tcp_clear_md5_list(struct sock *sk);
1856struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1857 const struct sock *addr_sk);
1858
1859#ifdef CONFIG_TCP_MD5SIG
1860struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1861 const union tcp_md5_addr *addr,
1862 int family, bool any_l3index);
1863static inline struct tcp_md5sig_key *
1864tcp_md5_do_lookup(const struct sock *sk, int l3index,
1865 const union tcp_md5_addr *addr, int family)
1866{
1867 if (!static_branch_unlikely(&tcp_md5_needed.key))
1868 return NULL;
1869 return __tcp_md5_do_lookup(sk, l3index, addr, family, false);
1870}
1871
1872static inline struct tcp_md5sig_key *
1873tcp_md5_do_lookup_any_l3index(const struct sock *sk,
1874 const union tcp_md5_addr *addr, int family)
1875{
1876 if (!static_branch_unlikely(&tcp_md5_needed.key))
1877 return NULL;
1878 return __tcp_md5_do_lookup(sk, 0, addr, family, true);
1879}
1880
1881#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1882#else
1883static inline struct tcp_md5sig_key *
1884tcp_md5_do_lookup(const struct sock *sk, int l3index,
1885 const union tcp_md5_addr *addr, int family)
1886{
1887 return NULL;
1888}
1889
1890static inline struct tcp_md5sig_key *
1891tcp_md5_do_lookup_any_l3index(const struct sock *sk,
1892 const union tcp_md5_addr *addr, int family)
1893{
1894 return NULL;
1895}
1896
1897#define tcp_twsk_md5_key(twsk) NULL
1898#endif
1899
1900int tcp_md5_alloc_sigpool(void);
1901void tcp_md5_release_sigpool(void);
1902void tcp_md5_add_sigpool(void);
1903extern int tcp_md5_sigpool_id;
1904
1905int tcp_md5_hash_key(struct tcp_sigpool *hp,
1906 const struct tcp_md5sig_key *key);
1907
1908/* From tcp_fastopen.c */
1909void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1910 struct tcp_fastopen_cookie *cookie);
1911void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1912 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1913 u16 try_exp);
1914struct tcp_fastopen_request {
1915 /* Fast Open cookie. Size 0 means a cookie request */
1916 struct tcp_fastopen_cookie cookie;
1917 struct msghdr *data; /* data in MSG_FASTOPEN */
1918 size_t size;
1919 int copied; /* queued in tcp_connect() */
1920 struct ubuf_info *uarg;
1921};
1922void tcp_free_fastopen_req(struct tcp_sock *tp);
1923void tcp_fastopen_destroy_cipher(struct sock *sk);
1924void tcp_fastopen_ctx_destroy(struct net *net);
1925int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1926 void *primary_key, void *backup_key);
1927int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1928 u64 *key);
1929void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1930struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1931 struct request_sock *req,
1932 struct tcp_fastopen_cookie *foc,
1933 const struct dst_entry *dst);
1934void tcp_fastopen_init_key_once(struct net *net);
1935bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1936 struct tcp_fastopen_cookie *cookie);
1937bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1938#define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1939#define TCP_FASTOPEN_KEY_MAX 2
1940#define TCP_FASTOPEN_KEY_BUF_LENGTH \
1941 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1942
1943/* Fastopen key context */
1944struct tcp_fastopen_context {
1945 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1946 int num;
1947 struct rcu_head rcu;
1948};
1949
1950void tcp_fastopen_active_disable(struct sock *sk);
1951bool tcp_fastopen_active_should_disable(struct sock *sk);
1952void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1953void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1954
1955/* Caller needs to wrap with rcu_read_(un)lock() */
1956static inline
1957struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1958{
1959 struct tcp_fastopen_context *ctx;
1960
1961 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1962 if (!ctx)
1963 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1964 return ctx;
1965}
1966
1967static inline
1968bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1969 const struct tcp_fastopen_cookie *orig)
1970{
1971 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1972 orig->len == foc->len &&
1973 !memcmp(orig->val, foc->val, foc->len))
1974 return true;
1975 return false;
1976}
1977
1978static inline
1979int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1980{
1981 return ctx->num;
1982}
1983
1984/* Latencies incurred by various limits for a sender. They are
1985 * chronograph-like stats that are mutually exclusive.
1986 */
1987enum tcp_chrono {
1988 TCP_CHRONO_UNSPEC,
1989 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1990 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1991 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1992 __TCP_CHRONO_MAX,
1993};
1994
1995void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1996void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1997
1998/* This helper is needed, because skb->tcp_tsorted_anchor uses
1999 * the same memory storage than skb->destructor/_skb_refdst
2000 */
2001static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
2002{
2003 skb->destructor = NULL;
2004 skb->_skb_refdst = 0UL;
2005}
2006
2007#define tcp_skb_tsorted_save(skb) { \
2008 unsigned long _save = skb->_skb_refdst; \
2009 skb->_skb_refdst = 0UL;
2010
2011#define tcp_skb_tsorted_restore(skb) \
2012 skb->_skb_refdst = _save; \
2013}
2014
2015void tcp_write_queue_purge(struct sock *sk);
2016
2017static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
2018{
2019 return skb_rb_first(&sk->tcp_rtx_queue);
2020}
2021
2022static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
2023{
2024 return skb_rb_last(&sk->tcp_rtx_queue);
2025}
2026
2027static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
2028{
2029 return skb_peek_tail(&sk->sk_write_queue);
2030}
2031
2032#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
2033 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
2034
2035static inline struct sk_buff *tcp_send_head(const struct sock *sk)
2036{
2037 return skb_peek(&sk->sk_write_queue);
2038}
2039
2040static inline bool tcp_skb_is_last(const struct sock *sk,
2041 const struct sk_buff *skb)
2042{
2043 return skb_queue_is_last(&sk->sk_write_queue, skb);
2044}
2045
2046/**
2047 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
2048 * @sk: socket
2049 *
2050 * Since the write queue can have a temporary empty skb in it,
2051 * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
2052 */
2053static inline bool tcp_write_queue_empty(const struct sock *sk)
2054{
2055 const struct tcp_sock *tp = tcp_sk(sk);
2056
2057 return tp->write_seq == tp->snd_nxt;
2058}
2059
2060static inline bool tcp_rtx_queue_empty(const struct sock *sk)
2061{
2062 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
2063}
2064
2065static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
2066{
2067 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
2068}
2069
2070static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
2071{
2072 __skb_queue_tail(&sk->sk_write_queue, skb);
2073
2074 /* Queue it, remembering where we must start sending. */
2075 if (sk->sk_write_queue.next == skb)
2076 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
2077}
2078
2079/* Insert new before skb on the write queue of sk. */
2080static inline void tcp_insert_write_queue_before(struct sk_buff *new,
2081 struct sk_buff *skb,
2082 struct sock *sk)
2083{
2084 __skb_queue_before(&sk->sk_write_queue, skb, new);
2085}
2086
2087static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
2088{
2089 tcp_skb_tsorted_anchor_cleanup(skb);
2090 __skb_unlink(skb, &sk->sk_write_queue);
2091}
2092
2093void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
2094
2095static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
2096{
2097 tcp_skb_tsorted_anchor_cleanup(skb);
2098 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
2099}
2100
2101static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
2102{
2103 list_del(&skb->tcp_tsorted_anchor);
2104 tcp_rtx_queue_unlink(skb, sk);
2105 tcp_wmem_free_skb(sk, skb);
2106}
2107
2108static inline void tcp_write_collapse_fence(struct sock *sk)
2109{
2110 struct sk_buff *skb = tcp_write_queue_tail(sk);
2111
2112 if (skb)
2113 TCP_SKB_CB(skb)->eor = 1;
2114}
2115
2116static inline void tcp_push_pending_frames(struct sock *sk)
2117{
2118 if (tcp_send_head(sk)) {
2119 struct tcp_sock *tp = tcp_sk(sk);
2120
2121 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
2122 }
2123}
2124
2125/* Start sequence of the skb just after the highest skb with SACKed
2126 * bit, valid only if sacked_out > 0 or when the caller has ensured
2127 * validity by itself.
2128 */
2129static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
2130{
2131 if (!tp->sacked_out)
2132 return tp->snd_una;
2133
2134 if (tp->highest_sack == NULL)
2135 return tp->snd_nxt;
2136
2137 return TCP_SKB_CB(tp->highest_sack)->seq;
2138}
2139
2140static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
2141{
2142 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
2143}
2144
2145static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
2146{
2147 return tcp_sk(sk)->highest_sack;
2148}
2149
2150static inline void tcp_highest_sack_reset(struct sock *sk)
2151{
2152 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
2153}
2154
2155/* Called when old skb is about to be deleted and replaced by new skb */
2156static inline void tcp_highest_sack_replace(struct sock *sk,
2157 struct sk_buff *old,
2158 struct sk_buff *new)
2159{
2160 if (old == tcp_highest_sack(sk))
2161 tcp_sk(sk)->highest_sack = new;
2162}
2163
2164/* This helper checks if socket has IP_TRANSPARENT set */
2165static inline bool inet_sk_transparent(const struct sock *sk)
2166{
2167 switch (sk->sk_state) {
2168 case TCP_TIME_WAIT:
2169 return inet_twsk(sk)->tw_transparent;
2170 case TCP_NEW_SYN_RECV:
2171 return inet_rsk(inet_reqsk(sk))->no_srccheck;
2172 }
2173 return inet_test_bit(TRANSPARENT, sk);
2174}
2175
2176/* Determines whether this is a thin stream (which may suffer from
2177 * increased latency). Used to trigger latency-reducing mechanisms.
2178 */
2179static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
2180{
2181 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
2182}
2183
2184/* /proc */
2185enum tcp_seq_states {
2186 TCP_SEQ_STATE_LISTENING,
2187 TCP_SEQ_STATE_ESTABLISHED,
2188};
2189
2190void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
2191void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
2192void tcp_seq_stop(struct seq_file *seq, void *v);
2193
2194struct tcp_seq_afinfo {
2195 sa_family_t family;
2196};
2197
2198struct tcp_iter_state {
2199 struct seq_net_private p;
2200 enum tcp_seq_states state;
2201 struct sock *syn_wait_sk;
2202 int bucket, offset, sbucket, num;
2203 loff_t last_pos;
2204};
2205
2206extern struct request_sock_ops tcp_request_sock_ops;
2207extern struct request_sock_ops tcp6_request_sock_ops;
2208
2209void tcp_v4_destroy_sock(struct sock *sk);
2210
2211struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
2212 netdev_features_t features);
2213struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb);
2214struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th);
2215struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
2216 struct tcphdr *th);
2217INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
2218INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
2219INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
2220INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
2221#ifdef CONFIG_INET
2222void tcp_gro_complete(struct sk_buff *skb);
2223#else
2224static inline void tcp_gro_complete(struct sk_buff *skb) { }
2225#endif
2226
2227void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
2228
2229static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
2230{
2231 struct net *net = sock_net((struct sock *)tp);
2232 u32 val;
2233
2234 val = READ_ONCE(tp->notsent_lowat);
2235
2236 return val ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);
2237}
2238
2239bool tcp_stream_memory_free(const struct sock *sk, int wake);
2240
2241#ifdef CONFIG_PROC_FS
2242int tcp4_proc_init(void);
2243void tcp4_proc_exit(void);
2244#endif
2245
2246int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
2247int tcp_conn_request(struct request_sock_ops *rsk_ops,
2248 const struct tcp_request_sock_ops *af_ops,
2249 struct sock *sk, struct sk_buff *skb);
2250
2251/* TCP af-specific functions */
2252struct tcp_sock_af_ops {
2253#ifdef CONFIG_TCP_MD5SIG
2254 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
2255 const struct sock *addr_sk);
2256 int (*calc_md5_hash)(char *location,
2257 const struct tcp_md5sig_key *md5,
2258 const struct sock *sk,
2259 const struct sk_buff *skb);
2260 int (*md5_parse)(struct sock *sk,
2261 int optname,
2262 sockptr_t optval,
2263 int optlen);
2264#endif
2265#ifdef CONFIG_TCP_AO
2266 int (*ao_parse)(struct sock *sk, int optname, sockptr_t optval, int optlen);
2267 struct tcp_ao_key *(*ao_lookup)(const struct sock *sk,
2268 struct sock *addr_sk,
2269 int sndid, int rcvid);
2270 int (*ao_calc_key_sk)(struct tcp_ao_key *mkt, u8 *key,
2271 const struct sock *sk,
2272 __be32 sisn, __be32 disn, bool send);
2273 int (*calc_ao_hash)(char *location, struct tcp_ao_key *ao,
2274 const struct sock *sk, const struct sk_buff *skb,
2275 const u8 *tkey, int hash_offset, u32 sne);
2276#endif
2277};
2278
2279struct tcp_request_sock_ops {
2280 u16 mss_clamp;
2281#ifdef CONFIG_TCP_MD5SIG
2282 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2283 const struct sock *addr_sk);
2284 int (*calc_md5_hash) (char *location,
2285 const struct tcp_md5sig_key *md5,
2286 const struct sock *sk,
2287 const struct sk_buff *skb);
2288#endif
2289#ifdef CONFIG_TCP_AO
2290 struct tcp_ao_key *(*ao_lookup)(const struct sock *sk,
2291 struct request_sock *req,
2292 int sndid, int rcvid);
2293 int (*ao_calc_key)(struct tcp_ao_key *mkt, u8 *key, struct request_sock *sk);
2294 int (*ao_synack_hash)(char *ao_hash, struct tcp_ao_key *mkt,
2295 struct request_sock *req, const struct sk_buff *skb,
2296 int hash_offset, u32 sne);
2297#endif
2298#ifdef CONFIG_SYN_COOKIES
2299 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
2300 __u16 *mss);
2301#endif
2302 struct dst_entry *(*route_req)(const struct sock *sk,
2303 struct sk_buff *skb,
2304 struct flowi *fl,
2305 struct request_sock *req,
2306 u32 tw_isn);
2307 u32 (*init_seq)(const struct sk_buff *skb);
2308 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2309 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2310 struct flowi *fl, struct request_sock *req,
2311 struct tcp_fastopen_cookie *foc,
2312 enum tcp_synack_type synack_type,
2313 struct sk_buff *syn_skb);
2314};
2315
2316extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2317#if IS_ENABLED(CONFIG_IPV6)
2318extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2319#endif
2320
2321#ifdef CONFIG_SYN_COOKIES
2322static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2323 const struct sock *sk, struct sk_buff *skb,
2324 __u16 *mss)
2325{
2326 tcp_synq_overflow(sk);
2327 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2328 return ops->cookie_init_seq(skb, mss);
2329}
2330#else
2331static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2332 const struct sock *sk, struct sk_buff *skb,
2333 __u16 *mss)
2334{
2335 return 0;
2336}
2337#endif
2338
2339struct tcp_key {
2340 union {
2341 struct {
2342 struct tcp_ao_key *ao_key;
2343 char *traffic_key;
2344 u32 sne;
2345 u8 rcv_next;
2346 };
2347 struct tcp_md5sig_key *md5_key;
2348 };
2349 enum {
2350 TCP_KEY_NONE = 0,
2351 TCP_KEY_MD5,
2352 TCP_KEY_AO,
2353 } type;
2354};
2355
2356static inline void tcp_get_current_key(const struct sock *sk,
2357 struct tcp_key *out)
2358{
2359#if defined(CONFIG_TCP_AO) || defined(CONFIG_TCP_MD5SIG)
2360 const struct tcp_sock *tp = tcp_sk(sk);
2361#endif
2362
2363#ifdef CONFIG_TCP_AO
2364 if (static_branch_unlikely(&tcp_ao_needed.key)) {
2365 struct tcp_ao_info *ao;
2366
2367 ao = rcu_dereference_protected(tp->ao_info,
2368 lockdep_sock_is_held(sk));
2369 if (ao) {
2370 out->ao_key = READ_ONCE(ao->current_key);
2371 out->type = TCP_KEY_AO;
2372 return;
2373 }
2374 }
2375#endif
2376#ifdef CONFIG_TCP_MD5SIG
2377 if (static_branch_unlikely(&tcp_md5_needed.key) &&
2378 rcu_access_pointer(tp->md5sig_info)) {
2379 out->md5_key = tp->af_specific->md5_lookup(sk, sk);
2380 if (out->md5_key) {
2381 out->type = TCP_KEY_MD5;
2382 return;
2383 }
2384 }
2385#endif
2386 out->type = TCP_KEY_NONE;
2387}
2388
2389static inline bool tcp_key_is_md5(const struct tcp_key *key)
2390{
2391 if (static_branch_tcp_md5())
2392 return key->type == TCP_KEY_MD5;
2393 return false;
2394}
2395
2396static inline bool tcp_key_is_ao(const struct tcp_key *key)
2397{
2398 if (static_branch_tcp_ao())
2399 return key->type == TCP_KEY_AO;
2400 return false;
2401}
2402
2403int tcpv4_offload_init(void);
2404
2405void tcp_v4_init(void);
2406void tcp_init(void);
2407
2408/* tcp_recovery.c */
2409void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2410void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2411extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2412 u32 reo_wnd);
2413extern bool tcp_rack_mark_lost(struct sock *sk);
2414extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2415 u64 xmit_time);
2416extern void tcp_rack_reo_timeout(struct sock *sk);
2417extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2418
2419/* tcp_plb.c */
2420
2421/*
2422 * Scaling factor for fractions in PLB. For example, tcp_plb_update_state
2423 * expects cong_ratio which represents fraction of traffic that experienced
2424 * congestion over a single RTT. In order to avoid floating point operations,
2425 * this fraction should be mapped to (1 << TCP_PLB_SCALE) and passed in.
2426 */
2427#define TCP_PLB_SCALE 8
2428
2429/* State for PLB (Protective Load Balancing) for a single TCP connection. */
2430struct tcp_plb_state {
2431 u8 consec_cong_rounds:5, /* consecutive congested rounds */
2432 unused:3;
2433 u32 pause_until; /* jiffies32 when PLB can resume rerouting */
2434};
2435
2436static inline void tcp_plb_init(const struct sock *sk,
2437 struct tcp_plb_state *plb)
2438{
2439 plb->consec_cong_rounds = 0;
2440 plb->pause_until = 0;
2441}
2442void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb,
2443 const int cong_ratio);
2444void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb);
2445void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb);
2446
2447static inline void tcp_warn_once(const struct sock *sk, bool cond, const char *str)
2448{
2449 WARN_ONCE(cond,
2450 "%scwn:%u out:%u sacked:%u lost:%u retrans:%u tlp_high_seq:%u sk_state:%u ca_state:%u advmss:%u mss_cache:%u pmtu:%u\n",
2451 str,
2452 tcp_snd_cwnd(tcp_sk(sk)),
2453 tcp_sk(sk)->packets_out, tcp_sk(sk)->sacked_out,
2454 tcp_sk(sk)->lost_out, tcp_sk(sk)->retrans_out,
2455 tcp_sk(sk)->tlp_high_seq, sk->sk_state,
2456 inet_csk(sk)->icsk_ca_state,
2457 tcp_sk(sk)->advmss, tcp_sk(sk)->mss_cache,
2458 inet_csk(sk)->icsk_pmtu_cookie);
2459}
2460
2461/* At how many usecs into the future should the RTO fire? */
2462static inline s64 tcp_rto_delta_us(const struct sock *sk)
2463{
2464 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2465 u32 rto = inet_csk(sk)->icsk_rto;
2466
2467 if (likely(skb)) {
2468 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2469
2470 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2471 } else {
2472 tcp_warn_once(sk, 1, "rtx queue empty: ");
2473 return jiffies_to_usecs(rto);
2474 }
2475
2476}
2477
2478/*
2479 * Save and compile IPv4 options, return a pointer to it
2480 */
2481static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2482 struct sk_buff *skb)
2483{
2484 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2485 struct ip_options_rcu *dopt = NULL;
2486
2487 if (opt->optlen) {
2488 int opt_size = sizeof(*dopt) + opt->optlen;
2489
2490 dopt = kmalloc(opt_size, GFP_ATOMIC);
2491 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2492 kfree(dopt);
2493 dopt = NULL;
2494 }
2495 }
2496 return dopt;
2497}
2498
2499/* locally generated TCP pure ACKs have skb->truesize == 2
2500 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2501 * This is much faster than dissecting the packet to find out.
2502 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2503 */
2504static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2505{
2506 return skb->truesize == 2;
2507}
2508
2509static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2510{
2511 skb->truesize = 2;
2512}
2513
2514static inline int tcp_inq(struct sock *sk)
2515{
2516 struct tcp_sock *tp = tcp_sk(sk);
2517 int answ;
2518
2519 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2520 answ = 0;
2521 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2522 !tp->urg_data ||
2523 before(tp->urg_seq, tp->copied_seq) ||
2524 !before(tp->urg_seq, tp->rcv_nxt)) {
2525
2526 answ = tp->rcv_nxt - tp->copied_seq;
2527
2528 /* Subtract 1, if FIN was received */
2529 if (answ && sock_flag(sk, SOCK_DONE))
2530 answ--;
2531 } else {
2532 answ = tp->urg_seq - tp->copied_seq;
2533 }
2534
2535 return answ;
2536}
2537
2538int tcp_peek_len(struct socket *sock);
2539
2540static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2541{
2542 u16 segs_in;
2543
2544 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2545
2546 /* We update these fields while other threads might
2547 * read them from tcp_get_info()
2548 */
2549 WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in);
2550 if (skb->len > tcp_hdrlen(skb))
2551 WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in);
2552}
2553
2554/*
2555 * TCP listen path runs lockless.
2556 * We forced "struct sock" to be const qualified to make sure
2557 * we don't modify one of its field by mistake.
2558 * Here, we increment sk_drops which is an atomic_t, so we can safely
2559 * make sock writable again.
2560 */
2561static inline void tcp_listendrop(const struct sock *sk)
2562{
2563 atomic_inc(&((struct sock *)sk)->sk_drops);
2564 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2565}
2566
2567enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2568
2569/*
2570 * Interface for adding Upper Level Protocols over TCP
2571 */
2572
2573#define TCP_ULP_NAME_MAX 16
2574#define TCP_ULP_MAX 128
2575#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2576
2577struct tcp_ulp_ops {
2578 struct list_head list;
2579
2580 /* initialize ulp */
2581 int (*init)(struct sock *sk);
2582 /* update ulp */
2583 void (*update)(struct sock *sk, struct proto *p,
2584 void (*write_space)(struct sock *sk));
2585 /* cleanup ulp */
2586 void (*release)(struct sock *sk);
2587 /* diagnostic */
2588 int (*get_info)(struct sock *sk, struct sk_buff *skb);
2589 size_t (*get_info_size)(const struct sock *sk);
2590 /* clone ulp */
2591 void (*clone)(const struct request_sock *req, struct sock *newsk,
2592 const gfp_t priority);
2593
2594 char name[TCP_ULP_NAME_MAX];
2595 struct module *owner;
2596};
2597int tcp_register_ulp(struct tcp_ulp_ops *type);
2598void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2599int tcp_set_ulp(struct sock *sk, const char *name);
2600void tcp_get_available_ulp(char *buf, size_t len);
2601void tcp_cleanup_ulp(struct sock *sk);
2602void tcp_update_ulp(struct sock *sk, struct proto *p,
2603 void (*write_space)(struct sock *sk));
2604
2605#define MODULE_ALIAS_TCP_ULP(name) \
2606 __MODULE_INFO(alias, alias_userspace, name); \
2607 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2608
2609#ifdef CONFIG_NET_SOCK_MSG
2610struct sk_msg;
2611struct sk_psock;
2612
2613#ifdef CONFIG_BPF_SYSCALL
2614int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
2615void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2616#endif /* CONFIG_BPF_SYSCALL */
2617
2618#ifdef CONFIG_INET
2619void tcp_eat_skb(struct sock *sk, struct sk_buff *skb);
2620#else
2621static inline void tcp_eat_skb(struct sock *sk, struct sk_buff *skb)
2622{
2623}
2624#endif
2625
2626int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
2627 struct sk_msg *msg, u32 bytes, int flags);
2628#endif /* CONFIG_NET_SOCK_MSG */
2629
2630#if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)
2631static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2632{
2633}
2634#endif
2635
2636#ifdef CONFIG_CGROUP_BPF
2637static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2638 struct sk_buff *skb,
2639 unsigned int end_offset)
2640{
2641 skops->skb = skb;
2642 skops->skb_data_end = skb->data + end_offset;
2643}
2644#else
2645static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2646 struct sk_buff *skb,
2647 unsigned int end_offset)
2648{
2649}
2650#endif
2651
2652/* Call BPF_SOCK_OPS program that returns an int. If the return value
2653 * is < 0, then the BPF op failed (for example if the loaded BPF
2654 * program does not support the chosen operation or there is no BPF
2655 * program loaded).
2656 */
2657#ifdef CONFIG_BPF
2658static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2659{
2660 struct bpf_sock_ops_kern sock_ops;
2661 int ret;
2662
2663 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2664 if (sk_fullsock(sk)) {
2665 sock_ops.is_fullsock = 1;
2666 sock_owned_by_me(sk);
2667 }
2668
2669 sock_ops.sk = sk;
2670 sock_ops.op = op;
2671 if (nargs > 0)
2672 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2673
2674 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2675 if (ret == 0)
2676 ret = sock_ops.reply;
2677 else
2678 ret = -1;
2679 return ret;
2680}
2681
2682static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2683{
2684 u32 args[2] = {arg1, arg2};
2685
2686 return tcp_call_bpf(sk, op, 2, args);
2687}
2688
2689static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2690 u32 arg3)
2691{
2692 u32 args[3] = {arg1, arg2, arg3};
2693
2694 return tcp_call_bpf(sk, op, 3, args);
2695}
2696
2697#else
2698static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2699{
2700 return -EPERM;
2701}
2702
2703static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2704{
2705 return -EPERM;
2706}
2707
2708static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2709 u32 arg3)
2710{
2711 return -EPERM;
2712}
2713
2714#endif
2715
2716static inline u32 tcp_timeout_init(struct sock *sk)
2717{
2718 int timeout;
2719
2720 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2721
2722 if (timeout <= 0)
2723 timeout = TCP_TIMEOUT_INIT;
2724 return min_t(int, timeout, TCP_RTO_MAX);
2725}
2726
2727static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2728{
2729 int rwnd;
2730
2731 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2732
2733 if (rwnd < 0)
2734 rwnd = 0;
2735 return rwnd;
2736}
2737
2738static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2739{
2740 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2741}
2742
2743static inline void tcp_bpf_rtt(struct sock *sk, long mrtt, u32 srtt)
2744{
2745 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2746 tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_RTT_CB, mrtt, srtt);
2747}
2748
2749#if IS_ENABLED(CONFIG_SMC)
2750extern struct static_key_false tcp_have_smc;
2751#endif
2752
2753#if IS_ENABLED(CONFIG_TLS_DEVICE)
2754void clean_acked_data_enable(struct inet_connection_sock *icsk,
2755 void (*cad)(struct sock *sk, u32 ack_seq));
2756void clean_acked_data_disable(struct inet_connection_sock *icsk);
2757void clean_acked_data_flush(void);
2758#endif
2759
2760DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2761static inline void tcp_add_tx_delay(struct sk_buff *skb,
2762 const struct tcp_sock *tp)
2763{
2764 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2765 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2766}
2767
2768/* Compute Earliest Departure Time for some control packets
2769 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2770 */
2771static inline u64 tcp_transmit_time(const struct sock *sk)
2772{
2773 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2774 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2775 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2776
2777 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;
2778 }
2779 return 0;
2780}
2781
2782static inline int tcp_parse_auth_options(const struct tcphdr *th,
2783 const u8 **md5_hash, const struct tcp_ao_hdr **aoh)
2784{
2785 const u8 *md5_tmp, *ao_tmp;
2786 int ret;
2787
2788 ret = tcp_do_parse_auth_options(th, &md5_tmp, &ao_tmp);
2789 if (ret)
2790 return ret;
2791
2792 if (md5_hash)
2793 *md5_hash = md5_tmp;
2794
2795 if (aoh) {
2796 if (!ao_tmp)
2797 *aoh = NULL;
2798 else
2799 *aoh = (struct tcp_ao_hdr *)(ao_tmp - 2);
2800 }
2801
2802 return 0;
2803}
2804
2805static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
2806 int family, int l3index, bool stat_inc)
2807{
2808#ifdef CONFIG_TCP_AO
2809 struct tcp_ao_info *ao_info;
2810 struct tcp_ao_key *ao_key;
2811
2812 if (!static_branch_unlikely(&tcp_ao_needed.key))
2813 return false;
2814
2815 ao_info = rcu_dereference_check(tcp_sk(sk)->ao_info,
2816 lockdep_sock_is_held(sk));
2817 if (!ao_info)
2818 return false;
2819
2820 ao_key = tcp_ao_do_lookup(sk, l3index, saddr, family, -1, -1);
2821 if (ao_info->ao_required || ao_key) {
2822 if (stat_inc) {
2823 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOREQUIRED);
2824 atomic64_inc(&ao_info->counters.ao_required);
2825 }
2826 return true;
2827 }
2828#endif
2829 return false;
2830}
2831
2832enum skb_drop_reason tcp_inbound_hash(struct sock *sk,
2833 const struct request_sock *req, const struct sk_buff *skb,
2834 const void *saddr, const void *daddr,
2835 int family, int dif, int sdif);
2836
2837#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 */